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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2017	Feb. 21, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Trading Symbol	ZIOP
Entity Registrant Name	ZIOPHARM ONCOLOGY INC
Entity Central Index Key	0001107421
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		142,398,936
Entity Public Float			$ 808,804,937

BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 70,946	$ 81,053
Receivables	19	21
Prepaid expenses and other current assets	19,818	23,810
Total current assets	90,783	104,884
Property and equipment, net	1,211	843
Deposits	128	128
Other non-current assets	13,484	493
Total assets	105,606	106,348
Current liabilities:
Accounts payable	4,417	156
Accrued expenses	9,909	9,109
Deferred revenue - current portion	6,389	6,389
Deferred rent - current portion	141	155
Total current liabilities	20,856	15,809
Deferred revenue, net of current portion	35,139	41,528
Deferred rent, net of current portion	1	126
Derivative liabilities	2,424	862
Total liabilities	58,420	58,325
Commitments and contingencies (Note 7)
Preferred stock, $0.001 par value, 30,000,000 shares authorized
Stockholders' deficit:
Common stock, $0.001 par value; 250,000,000 shares authorized; 142,658,037 and 132,376,670 shares issued and outstanding at December 31, 2017 and 2016, respectively	143	132
Additional paid-in capital - common stock	615,493	580,567
Accumulated deficit	(712,442)	(657,997)
Total stockholders' deficit	(96,806)	(77,298)
Total liabilities and stockholders' deficit	105,606	106,348
Series 1 Preferred Stock
Current liabilities:
Series 1 preferred stock, $1,200 stated value; 250,000 designated; 119,644 and 106,184 shares issued and outstanding at December 31, 2017 and respectively; liquidation value of $143.6 million and $127.4 million at December 31, 2017 and 2016, respectively	$ 143,992	$ 125,321

BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	30,000,000	30,000,000
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	142,658,037	132,376,670
Common stock, shares outstanding	142,658,037	132,376,670
Series 1 Preferred Stock
Preferred stock, stated value	$ 1,200	$ 1,200
Preferred stock, shares authorized	250,000	250,000
Preferred stock, shares issued	119,644	106,184
Preferred stock, shares outstanding	119,644	106,184
Preferred stock, liquidation preference	$ 143.6	$ 127.4

STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Collaboration revenue	$ 6,389	$ 6,861	$ 4,332
Operating expenses:
Research and development	45,084	157,791	106,785
General and administrative	14,798	14,377	17,647
Total operating expenses	59,882	172,168	124,432
Loss from operations	(53,493)	(165,307)	(120,100)
Other income (expense), net	465	134	12
Change in fair value of derivative liabilities	(1,295)	(124)
Net loss	(54,323)	(165,297)	(120,088)
Preferred stock dividends	(18,938)	(7,123)
Net loss applicable to common stockholders	$ (73,261)	$ (172,420)	$ (120,088)
Basic and diluted net loss per share	$ (0.53)	$ (1.32)	$ (0.96)
Weighted average common shares outstanding used to compute basic and diluted net loss per share	136,938,264	130,391,463	125,416,084

STATEMENTS OF CHANGES IN PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid In Capital Common Stock	Accumulated Deficit	Series 1 Preferred Stock - Mezzanine
Balance at Dec. 31, 2014	$ 33,841	$ 104	$ 406,349	$ (372,612)
Balance (in shares) at Dec. 31, 2014		104,452,105
Exercise of employee stock options	$ 4,568	$ 3	4,566
Exercise of employee stock options (in shares)	3,249,160	2,519,267
Stock-based compensation	$ 7,997		7,997
Issuance of restricted common stock		$ 2	(2)
Issuance of restricted common stock (in shares)		1,590,574
Issuance of common stock in licensing agreement	67,285	$ 12	67,273
Issuance of stock in a license agreement (in shares)		11,722,163
Repurchase of shares of restricted common stock	(518)		(518)
Repurchase of shares of restricted common stock (in shares)		(61,819)
Repurchase of common stock	(34)		(34)
Repurchase of common stock (Shares)		(3,711)
Issuance of common stock, net of commissions and expenses	94,320	$ 12	94,309
Issuance of common stock, net of commissions and expenses (in shares)		11,500,000
Net loss	(120,088)			(120,088)
Balance at Dec. 31, 2015	87,371	$ 132	579,939	(492,700)
Balance (in shares) at Dec. 31, 2015		131,718,579
Exercise of employee stock options	$ 714	$ 2	712
Exercise of employee stock options (in shares)	234,833	189,696
Stock-based compensation	$ 8,452		8,452
Issuance of restricted common stock		$ 712	(712)
Issuance of restricted common stock (in shares)		711,770
Issuance of common stock in licensing agreement	87		87		$ 118,242
Issuance of stock in a license agreement (in shares)					100,000
Repurchase of shares of restricted common stock	(1,500)	$ (2)	(1,498)
Repurchase of shares of restricted common stock (in shares)		(243,207)
Repurchase of common stock	(2)		(2)
Repurchase of common stock (Shares)		(168)
Preferred stock dividends					$ 7,079
Preferred stock dividends	(7,123)		(7,123)
Preferred stock dividends (in shares)					6,184
Net loss	(165,297)			(165,297)
Balance at Dec. 31, 2016	(77,298)	$ 132	580,567	(657,997)	$ 125,321
Balance (in shares) at Dec. 31, 2016		132,376,670			106,184
Exercise of employee stock options	$ 88	$ 1	87
Exercise of employee stock options (in shares)	180,000	59,864
Stock-based compensation	$ 8,454		8,454
Issuance of restricted common stock		$ 1	(1)
Issuance of restricted common stock (in shares)		907,032
Repurchase of common stock	(2,059)	$ (1)	(2,058)
Repurchase of common stock (Shares)		(394,267)
Issuance of common stock, net of commissions and expenses	47,270	$ 10	47,260
Issuance of common stock, net of commissions and expenses (in shares)		9,708,738
Preferred stock dividends					$ 18,672
Preferred stock dividends	(18,938)		(18,938)
Preferred stock dividends (in shares)					13,460
Net loss	(54,323)			(54,323)
Balance at Dec. 31, 2017	$ (96,806)	$ 143	615,493	(712,442)	$ 143,993
Balance (in shares) at Dec. 31, 2017		142,658,037			119,644
Cumulative effect adjustment (Note 3)			$ 122	$ (122)

STATEMENTS OF CHANGES IN PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Issuance of common stock, commissions and expenses	$ 2,700	$ 109	$ 6,305

STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss	$ (54,323)	$ (165,297)	$ (120,088)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	369	290	357
Stock-based compensation	8,454	8,452	7,997
Common stock issued in exchange for license agreement			67,285
Preferred stock issued in exchange for 2016 ECP amendment		118,936
Change in fair value of derivative liabilities	1,295	124
Issuance of common stock in a license agreement		87
(Increase) decrease in:
Receivables	2	425	(301)
Prepaid expenses and other current assets	3,992	(12,452)	(10,214)
Other noncurrent assets	(12,991)		(3)
Increase (decrease) in:
Accounts payable	4,261	(1,852)	4
Accrued expenses	800	203	1,724
Deferred revenue	(6,389)	(6,861)	53,418
Deferred rent	(139)	(380)	(189)
Net cash used in operating activities	(54,669)	(58,325)	(10)
Cash flows from investing activities:
Purchases of property and equipment	(737)	(551)	(412)
Net cash used in investing activities	(737)	(551)	(412)
Cash flows from financing activities:
Proceeds from exercise of stock options	88	714	4,568
Issuance of restricted common stock	(2,059)	(1,500)	(518)
Repurchase of common stock		(2)	(34)
Proceeds from issuance of common stock, net	47,270		94,320
Net cash provided by (used in) financing activities	45,299	(788)	98,336
Net decrease in cash and cash equivalents	(10,107)	(59,664)	97,914
Cash and cash equivalents, beginning of period	81,053	140,717	42,803
Cash and cash equivalents, end of period	70,946	81,053	140,717
Supplementary disclosure of cash flow information:
Cash paid for interest	0	0	0
Cash paid for income taxes	0	0	0
Supplementary disclosure of noncash investing and financing activities:
Issuance of stock			$ 67,285
Series 1 Preferred Stock
Supplementary disclosure of noncash investing and financing activities:
Issuance of stock		119,045
Payment of dividends in preferred stock	$ 18,938	$ 7,123

Organization and Going Concern

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Organization and Going Concern

Organization and Going Concern

ZIOPHARM Oncology, Inc., which is referred to herein as “ZIOPHARM,” the “Company,” or “we”, is a biopharmaceutical company seeking to develop, acquire, and commercialize, on its own or with partners, a diverse portfolio of immuno-oncology therapies.

The Company’s operations to date have consisted primarily of raising capital and conducting research and development. The Company’s fiscal year ends on December 31.

The Company has operated at a loss since its inception in 2003 and has minimal revenues. The Company anticipates that losses will continue for the foreseeable future. At December 31, 2017, the Company’s accumulated deficit was approximately $712.4 million. Given its current development plans, the Company anticipates cash resources will be sufficient to fund operations into the fourth quarter of 2018. The Company’s ability to continue operations after its current cash resources are exhausted depends on its ability to obtain additional financing or to achieve profitable operations, as to which no assurances can be given. Cash requirements may vary materially from those now planned because of changes in the Company’s focus and direction of its research and development programs, competitive and technical advances, patent developments, regulatory changes or other developments. Additional financing will be required to continue operations after the Company exhausts its current cash resources and to continue its long-term plans for clinical trials and new product development (Note 3).

As of December 31, 2017, the Company had approximately $70.9 million of cash and cash equivalents. Given its development plans, the Company anticipates cash resources will be sufficient to fund its operations into the fourth quarter of 2018 and the Company has no committed sources of additional capital. The forecast of cash resources is forward-looking information that involves risks and uncertainties, and the actual amount of the Company’s expenses could vary materially and adversely as a result of a number of factors. The Company has based its estimates on assumptions that may prove to be wrong, and the Company’s expenses could prove to be significantly higher than currently anticipated. Management does not know whether additional financing will be on terms favorable or acceptable to the Company when needed, if at all. If adequate additional funds are not available when required, or if the Company is unsuccessful in entering into partnership agreements for further development of its products, management may need to curtail development efforts. Based on the forecast, management determined that there is substantial doubt regarding our ability to continue as a going concern.

Financings

12 Months Ended

Dec. 31, 2017

Text Block [Abstract]

Financings

Financings

On February 3, 2015, the Company entered into an underwriting agreement with J.P. Morgan Securities LLC, as representative of the several underwriters named therein, relating to the issuance and sale of 10,000,000 shares of its common stock. The price to the public in the offering was $8.75 per share, and the underwriters agreed to purchase the shares from the Company pursuant to the underwriting agreement at a purchase price of $8.225 per share. Under the terms of the underwriting agreement, the Company also granted the underwriters an option, exercisable for 30 days, to purchase up to an additional 1,500,000 shares of common stock at a purchase price of $8.225 per share. The offering was made pursuant to the Company’s registration statement on Form S-3 (SEC File No. 333-201826) previously filed with the SEC, and a prospectus supplement thereunder. The underwriters purchased the 10,000,000 shares and the additional 1,500,000 shares on February 9 and February 17, 2015, respectively. The net proceeds from the offering were approximately $94.3 million after deducting underwriting discounts and estimated offering expenses paid by the Company.

On May 11, 2017, the Company sold in an underwritten offering an aggregate of 9,708,738 shares of its common stock to a single investor. The price to the investor in the offering was $5.15 per share, and the underwriters agreed to purchase the shares from the Company pursuant to the underwriting agreement at a purchase price of $4.893 per share. The offering was made pursuant to the Company’s registration statement on Form S-3ASR (File No. 333-201826) previously filed with the SEC, and a prospectus supplement thereunder. The net proceeds from the offering were approximately $47.3 million after deducting underwriting commissions and estimated offering expenses payable by the Company.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies

Basis of Presentation

The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America or U.S. GAAP.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Although the Company regularly assesses these estimates, actual results could differ from those estimates. Changes in estimates are recorded in the period in which they become known.

The Company’s most significant estimates and judgments used in the preparation of our financial statements are:

•

Clinical trial expenses;

•

Collaboration agreements;

•

Fair value measurements of stock-based compensation and Series 1 preferred stock (and related dividends); and

•

Income taxes.

Subsequent Events

The Company evaluated all events and transactions that occurred after the balance sheet date through the date of this filing. During this period, the Company did not have any material subsequent events that impacted its financial statements or disclosures.

Cash and Cash Equivalents

Cash equivalents consist primarily of demand deposit accounts and deposits in short-term U.S. treasury money market mutual funds. Cash equivalents are stated at cost, which approximates fair market value.

Concentrations of Credit Risk

Financial instruments which potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents. The Company maintains cash accounts in commercial banks, which may, at times, exceed federally insured limits. The Company has not experienced any losses in such accounts. The Company believes it is not exposed to any significant credit risk on cash and cash equivalents.

Property and Equipment

Property and equipment are recorded at cost. Expenditures for maintenance and repairs are charged to expense while the costs of significant improvements are capitalized. Depreciation is provided using the straight-line method over the following estimated useful lives of the related assets, which is between three and five years. Upon retirement or sale, the cost of the assets disposed of and the related accumulated depreciation are eliminated from the balance sheets and related gains or losses are reflected in the statements of operations.

Restricted Cash

Restricted cash consists of $388 thousand, which is restricted as collateral for the Company’s facility leases and included in current assets, and $104 thousand, which is restricted as collateral for a line of credit and is included in other assets.

Long-Lived Assets

The Company reviews the carrying values of its long-lived assets for possible impairment whenever events or changes in circumstances indicate that the carrying amounts of the assets may not be recoverable. Any long-lived assets held for disposal are reported at the lower of their carrying amounts or fair values less costs to sell.

Operating Segments

Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, the Company’s Chief Executive Officer, in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one operating segment and does not track expenses on a program-by-program basis.

Fair Value Measurements

The Company has certain financial assets and liabilities recorded at fair value which have been classified as Level 1, 2 or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements.

•

Level 1—Quoted prices in active markets for identical assets or liabilities.

•

Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

•

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Assets and liabilities measured at fair value on a recurring basis as of December 31, 2017 and 2016 are as follows:


($ in thousands)				Fair Value Measurements at Reporting Date Using
Description	Balance as of December 31, 2017			Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents	$	66,156		$	66,156	$	—	$	—

Derivative liabilities	$	(2,424	)	$	—	$	—	$	(2,424	)


($ in thousands)				Fair Value Measurements at Reporting Date Using
Description	Balance as of December 31, 2016			Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents	$	77,120		$	77,120	$	—	$	—

Derivative liabilities	$	(862	)	$	—	$	—	$	(862	)

The cash equivalents represent deposits in a short term United States treasury money market mutual fund quoted in an active market and classified as a Level 1 asset.

As discussed further in Notes 7 and 9, the Company issued Intrexon 100,000 shares of the Company’s Series 1 preferred stock, a new class of preferred stock authorized by the Company’s board of directors, in consideration of the parties entering into a Third Amendment to Exclusive Channel Partner Agreement, or the 2016 ECP Amendment, amending their existing Exclusive Channel Partner Agreement, effective January 6, 2011 and as amended to date, which the Company refers to as the Channel Agreement, and an Amendment to Exclusive Channel Collaboration Agreement, or the 2016 GvHD Amendment, amending their existing Exclusive Channel Collaboration Agreement, effective September 28, 2015, which the Company refers to as the GvHD Agreement.

At June 30, 2016, the Company’s Series 1 preferred stock was valued using a probability-weighted approach and a Monte Carlo simulation model. Additionally, the monthly dividends issued on the outstanding Series 1 preferred stock are valued using the same probability-weighted approach and a Monte Carlo simulation model. However, there is no adjustment or further revaluation after the initial valuation on the Series 1 preferred stock.

The Company’s Level 3 financial liabilities consist of a conversion option and a redemption feature associated with the Company’s Series 1 preferred stock issued to Intrexon that has been bifurcated from the Series 1 preferred stock and are accounted for as derivative liabilities at fair value. The preferred stock derivative liabilities were valued using a probability-weighted approach and a Monte Carlo simulation model. The fair value of the embedded derivatives was estimated using the “with” and “without” method where the preferred stock was first valued with all of its features (“with” scenario) and then without derivatives subject to the valuation analysis (“without” scenario). The fair value of the derivatives was then estimated as the difference between the fair value of the preferred stock in the “with” scenario and the preferred stock in the “without” scenario. See Note 7 for additional disclosures on the 2016 ECP Amendment and 2016 GvHD Amendment and Note 9 for additional disclosure on the rights and preferences of the Series 1 preferred stock and valuation methodology.

Revenue Recognition from Collaboration Agreements

The Company has primarily generated revenue through collaboration arrangements with strategic partners for the development and commercialization of product candidates. The Company recognizes revenue for each unit of accounting when evidence of an arrangement exists, delivery has occurred or services have been rendered, the seller’s price to the buyer is fixed or determinable and collectability is reasonably assured.

The Company’s collaboration agreements may provide for various types of payments, including upfront payments, funding of research and development, milestone payments, licensing fees and product royalties. The specifics of the Company’s significant agreements are detailed in Note 7.

The Company considers a variety of factors in determining the appropriate method of accounting for its collaboration agreements, including whether multiple deliverables can be separated and accounted for individually as separate units of accounting. Pursuant to the guidance in FASB Accounting Standards Codification (ASC) 605-25, Multiple-Element Arrangements (ASC 605-25), the Company evaluates multiple-element arrangements to determine whether the individual deliverables represent separate units of accounting or whether they must be accounted for as a combined unit of accounting. This evaluation involves subjective determinations and requires management to make judgments about the individual deliverables and whether such deliverables are separable from the other aspects of the contractual relationship. Deliverables are considered separate units of accounting provided that: (i) the delivered item(s) has value to the customer on a standalone basis and (ii) if the arrangement includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in the control of the Company. In assessing whether an item has standalone value, the Company considers factors such as the research, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. In addition, the Company considers whether the collaboration partner can use the other deliverable(s) for their intended purpose without the receipt of the remaining element(s), whether the value of the deliverable is dependent on the undelivered item(s) and whether there are other vendors that can provide the undelivered element(s). The Company’s collaboration arrangements do not contain a general right of return relative to the delivered item(s).

Where there are multiple deliverables within a collaboration agreement that cannot be separated and therefore are combined into a single unit of accounting, revenues are deferred and recognized over the estimated period of performance, which is typically the development term. If the deliverables can be separated, the Company applies the relevant revenue recognition guidance to each individual unit of accounting. The specific methodology for the recognition of the underlying revenue is determined on a case-by-case basis according to the facts and circumstances applicable to each agreement. Generally, the Company has accounted for its collaboration agreements as a single unit of accounting.

At the inception of an arrangement that includes milestone payments, the Company evaluates whether each milestone is substantive and at risk to both parties on the basis of the contingent nature of the milestone. This evaluation includes an assessment of whether: (i) the consideration is commensurate with either the Company’s performance to achieve the milestone or the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the Company’s performance to achieve the milestone, (ii) the consideration relates solely to past performance and (iii) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. The Company evaluates factors such as the scientific, clinical, regulatory, commercial and other risks that must be overcome to achieve the respective milestone and the level of effort and investment required to achieve the respective milestone in making this assessment. There is considerable judgement involved in determining whether a milestone satisfies all of the criteria required to conclude that a milestone is substantive. In accordance with FASB ASC 605-28, Milestone Method (ASC 605-28), revenue from substantive milestone payments is recognized in its entirety in the period in which the milestone is achieved, assuming all other revenue recognition criteria are met. Payments from milestones that are not considered substantive payment is deferred and recognized as revenue over the estimated remaining period of performance under the contract as the Company completes its performance obligations assuming all other revenue recognition criteria are met. Revenue from commercial milestone payments is accounted for as royalties and recorded as revenue upon achievement of the milestone, assuming all other revenue recognition criteria are met. Royalties are recognized as earned in accordance with the terms of various research and collaboration agreements.

Research and Development Costs

Research and development expenditures are charged to the statement of operations as incurred. Such costs include proprietary research and development activities, purchased research and development, and expenses associated with research and development contracts, whether performed by the Company or contracted with independent third parties.

Income Taxes

Income taxes are accounted for under the liability method. Deferred tax assets and liabilities are recognized for the estimated future tax consequences of temporary differences between the financial statement carrying amounts and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the year in which the temporary differences are expected to be recovered or settled. The Company evaluates the realizability of its deferred tax assets and establishes a valuation allowance when it is more likely than not that all or a portion of deferred tax assets will not be realized.

The Company accounts for uncertain tax positions using a “more-likely-than-not” threshold for recognizing and resolving uncertain tax positions. The evaluation of uncertain tax positions is based on factors including, but not limited to, changes in tax law, the measurement of tax positions taken or expected to be taken in tax returns, the effective settlement of matters subject to audit, new audit activity and changes in facts or circumstances related to a tax position. The Company evaluates this tax position on an annual basis. The Company also accrues for potential interest and penalties, related to unrecognized tax benefits in income tax expense (see Note 8).

Accounting for Stock-Based Compensation

Stock-based compensation cost is measured at the grant date, based on the estimated fair value of the award, and is recognized as expense over the employee’s requisite service period. Stock-based compensation expense is based on the number of awards ultimately expected to vest and is therefore reduced for an estimate of the awards that are expected to be forfeited prior to vesting. Consistent with prior years, the Company uses the Black-Scholes option pricing model which requires estimates of the expected term option holders will retain their options before exercising them and the estimated volatility of the Company’s common stock price over the expected term.

The Company recognizes the full impact of its share-based employee payment plans in the statements of operations for each of the years ended December 31, 2017, 2016, and 2015 and did not capitalize any such costs on the balance sheets. The Company recognized $2.5 million, $3.0 million, and $5.3 million of compensation expense related to vesting of stock options during the years ended December 31, 2017, 2016, and 2015, respectively. In the years ended December 31, 2017, 2016, and 2015, the Company recognized $6.0 million, $5.5 million, and $2.7 million of compensation expense, respectively, related to vesting of restricted stock (see Note 11). The total compensation expense relating to vesting of stock options and restricted stock awards for the years ended December 31, 2017, 2016, and 2015 was $8.5 million, $8.5 million, and $8.0 million, respectively. The following table presents share-based compensation expense included in the Company’s Statements of Operations:


	Year ended December 31,
(in thousands)	2017		2016		2015
Research and development	$	2,401	$	2,077	$	1,403
General and administrative		6,053		6,375		6,594

Share based employee compensation expense before tax		8,454		8,452		7,997
Income tax benefit		—		—		—

Net share based employee compensation expense	$	8,454	$	8,452	$	7,997

The fair value of each stock option is estimated at the date of grant using the Black-Scholes option pricing model. The estimated weighted-average fair value of stock options granted to employees in 2017, 2016, and 2015 was approximately $3.94, $4.43, and $10.47 per share, respectively. Assumptions regarding volatility, expected term, dividend yield and risk-free interest rate are required for the Black-Scholes model. The volatility assumption is based on the Company’s historical experience. The risk-free interest rate is based on a U.S. treasury note with a maturity similar to the option award’s expected life. The expected life represents the average period of time that options granted are expected to be outstanding. The Company calculated expected term using the simplified method described in SEC Staff Accounting Bulletin, or SAB, No. 107 and No. 110 as it continues to meet the requirements promulgated in SAB No. 110. The assumptions for volatility, expected life, dividend yield and risk-free interest rate are presented in the table below:


	2017	2016	2015
Weighted average risk-free interest rate	1.85 - 2.27%	1.27 - 2.09%	1.46 - 1.93%
Expected life in years	6	6	6
Expected volatility	80.31 - 81.03%	79.15 - 82.95%	79.13 - 86.81%
Expected dividend yield	0	0	0

Net Loss Per Share

Basic net loss per share is computed by dividing net loss by the weighted average number of common shares outstanding for the period. The Company’s potentially dilutive shares, which include outstanding common stock options, unvested restricted stock and preferred stock, have not been included in the computation of diluted net loss per share for any of the periods presented as the result would be antidilutive. Such potential common shares at December 31, 2017, 2016, and 2015 consist of the following:


	December 31,
	2017		2016		2015
Stock options		4,352,135		3,465,335		3,481,468
Unvested restricted stock		1,808,559		1,680,492		1,586,388
Preferred stock		34,134,524		20,465,067		—

	40,295,218		25,610,894		5,067,856

The Series 1 preferred stock automatically converts into shares of common stock upon the date the first approval in the United States of (i) a ZIOPHARM Product, as defined in and developed under the Exclusive Channel Partner Agreement dated as of January 6, 2011 and as amended from time to time, by and between the Company and Intrexon (now Precigen), or (ii) a Product, as defined in and developed under the Exclusive Channel Collaboration Agreement dated September 28, 2015 and as amended from time to time, by and between the Company and Intrexon (now Precigen), or (iii) a Product as defined in and developed under the License and Collaboration Agreement dated March 27, 2015 and as amended from time to time, by and among Intrexon (now Precigen), ARES TRADING, S.A. and the Company, is publicly announced. Assuming a conversion event date of December 31, 2017, the Series 1 preferred stock would convert into 34,134,524 shares of common stock using the greater of (i) the volume weighted average closing price of the Company’s Common Stock as reported by the Nasdaq Stock Market, LLC over previous the 20 trading days ending on the conversion event date or (ii) $1.00 per share. See Note 7 and Note 9 for additional disclosure regarding the 2016 ECP Amendment and 2016 GvHD Amendment, valuation methodology and significant assumptions.

New Accounting Pronouncements

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”) to provide updated guidance on revenue recognition. ASU 2014-09 requires a company to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies may need to use more judgment and make more estimates than under today’s guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price, and allocating the transaction price to each separate performance obligation. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which deferred the effective date of ASU 2014-09 by one year. Accordingly, ASU 2014-09 is effective for public business entities for annual reporting periods beginning after December 15, 2017, including interim reporting periods within each annual reporting period. In March 2016, the FASB issued ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross Versus Net), which clarifies the implementation guidance on principal versus agent considerations. In April 2016, the FASB issued ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing, which clarifies certain aspects of identifying performance obligations and licensing implementation guidance. In May 2016, the FASB issued ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients, which relates to disclosures of remaining performance obligations, as well as other amendments to guidance on collectability, non-cash consideration, and the presentation of sales and other similar taxes collected from customers. Collectively these amendments are referred to as “ASC 606”.

ASC 606 clarifies the principles for recognizing revenue and develops a common revenue standard for U.S. GAAP and International Financial Reporting Standards, or IFRS. This standard removes inconsistencies and weaknesses between U.S. GAAP and IFRS in revenue requirements, provides a more robust framework for addressing revenue issues, improves comparability of revenue recognition practices across entities, industries, jurisdictions, and capital markets, provides more useful information to users of financial statements through improved disclosure requirements, and simplifies the preparation of financial statements by reducing the number of requirements to which an entity must refer. This update is effective for annual periods beginning after December 15, 2017, including interim periods within that reporting period. The Company adopted this standard using the modified retrospective approach on January 1, 2018. The Company has substantially completed our assessment and the implementation resulted in a cumulative effect adjustment to accumulated deficit as of January 1, 2018 of approximately $8.1 million and a corresponding increase to the contract liability (formerly deferred revenue). The adjustment is related to the Company’s Ares Trading License and Collaboration Agreement (Note 7), which is the Company’s sole contract outstanding at January 1, 2018 (Note 3). The Company has a full valuation allowance so there will be no effect on incomes taxes as a result of this adoption.

The Company will recognize collaboration revenue under certain of the Company’s license or collaboration agreements that are within the scope of ASC 606. The terms of these agreements may contain multiple performance obligations, which may include licenses and research and development activities. The Company evaluates these agreements under ASC 606 to determine the distinct performance obligations.

Prior to recognizing revenue, the Company makes estimates of the transaction price, including variable consideration that are subject to a constraint. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur and when the uncertainty associated with the variable consideration is subsequently resolved. Variable consideration may include nonrefundable upfront license fees, payments for research and development activities, reimbursement of certain third-party costs, payments based upon the achievement of specified milestones, and royalty payments based on product sales derived from the collaboration.

If there are multiple distinct performance obligations, including material rights, the Company allocates the transaction price to each distinct performance obligation based on its relative standalone selling price. The standalone selling price is generally determined based on the prices charged to customers or using expected cost plus margin. Revenue is recognized by measuring the progress toward complete satisfaction of the performance obligations using an input measure, in accordance with ASC-340-40, Other Assets and Deferred Costs: Contracts with Customers.

As it relates to the Ares Trading License and Collaboration Agreement (Note 7), the Company determined that there were three performance obligations; the first performance obligation consists of the license and research development services and the other two performance obligations are material rights as it relates to potential future targets that have not yet been identified. The transaction price of $57.5 million was allocated to the performance obligations based on their relative standalone selling prices.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), or ASU 2016-02. The guidance in this ASU supersedes the leasing guidance in Leases (Topic 840). Under the new guidance, lessees are required to recognize lease assets and lease liabilities on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance leases or operating leases, with classification affecting the pattern of expense recognition in the statement of operations. The new standard is effective for annual reporting periods beginning after December 15, 2018, including interim reporting periods within each annual reporting period. The Company is currently evaluating the impact of the adoption of this ASU on the financial statements.

In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Accounting, or ASU 2016-09, to require changes to several areas of employee share-based payment accounting in an effort to simplify share-based reporting. ASU 2016-09 is effective for annual reporting periods beginning after December 15, 2016, including interim reporting periods within each annual reporting period. The Company adopted this standard on January 1, 2017. The update revises requirements in the following areas: minimum statutory withholding, accounting for income taxes, and forfeitures. Prior to adoption, the Company recognized share-based compensation, net of estimated forfeitures, over the vesting period of the grant. Upon adoption of ASU 2016-09, the Company elected to change its accounting policy to recognize forfeitures as they occur. The new forfeiture policy election was adopted using a modified retrospective approach with a cumulative effect adjustment recorded to retained earnings as of January 1, 2017. The update requires the Company to recognize the income tax effect of awards in the income statement when the awards vest or are settled. It also allows the Company to repurchase more of an employee’s shares than it can today for tax withholding purposes without triggering a liability. The income tax related items had no effect on the current period presentation and the Company maintains a full valuation allowance against its deferred tax assets.

In August 2016, the FASB issued ASU No. 2016-15, Classification of Certain Cash Receipts and Cash Payments, or ASU 2016-15, to address how certain cash receipts and cash payments are presented and classified in the statement of cash flows in an effort to reduce existing diversity in practice. The update includes eight specific cash flow issues and provides guidance on the appropriate cash flow presentation for each. ASU 2016-15 is effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within each annual reporting period. The Company is currently evaluating the impact of the adoption of this ASU on the financial statements.

In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash, or ASU 2016-18, to clarify how entities should present restricted cash and restricted cash equivalents in the statement of cash flows. Under this new update, entities are required to show the changes in the total of cash, cash equivalents, restricted cash, and restricted cash equivalents in the statement of cash flows. This guidance will be applied retrospectively and is effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within each annual reporting period. The Company is currently evaluating the impact of the adoption of this ASU on the financial statements and does not expect there to be a material impact on the financial statements.

In May 2017, the FASB issued ASU No. 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting, or ASU 2017-09, to clarify when to account for a change to the terms or conditions of a share-based payment award as a modification. Under this new guidance, modification accounting is required if the fair value, vesting conditions, or classification of the award changes as a result of the change in terms or conditions. ASU 2017-09 is effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within each annual reporting period. The Company does not expect the adoption of this guidance to have a material impact on the financial statements.

Property and Equipment, net

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property and Equipment, net

Property and Equipment, net

Property and equipment, net, consists of the following:


	December 31,
(in thousands)	2017			2016
Office and computer equipment	$	1,215		$	1,162
Software		913			907
Leasehold improvements		1,553			1,158
Research and development equipment		1,161			878

		4,842			4,105
Less: accumulated depreciation		(3,631	)		(3,262	)

Property and equipment, net	$	1,211		$	843

Depreciation charged to the statement of operations for the years ended December 31, 2017, 2016, and 2015 was $369 thousand, $290 thousand and $357 thousand, respectively.

Accrued Expenses

12 Months Ended

Dec. 31, 2017

Payables and Accruals [Abstract]

Accrued Expenses

Accrued Expenses

Accrued expenses consist of the following:


	December 31,
(in thousands)	2017		2016
Clinical consulting services	$	3,022	$	2,342
Preclinical services		2,210		2,693
Employee compensation		1,919		1,446
Payroll taxes and benefits		1,017		646
Manufacturing services		902		1,116
Accrued vacation		361		294
Professional services		256		488
Other consulting services		222		28
Accrued rent		—		56

Total	$	9,909	$	9,109

Related Party Transactions

12 Months Ended

Dec. 31, 2017

Related Party Transactions

Related Party Transactions

Collaborations with Intrexon/ Precigen

On January 6, 2011, the Company entered into the Channel Agreement with Intrexon (now Precigen) (Note 7). A director of the Company, Randal J. Kirk, is the chief executive officer, a director, and the largest stockholder of Intrexon.

On February 3, 2015, Intrexon purchased 1,440,000 shares of common stock in the Company’s public offering upon the same terms as others that participated in the offering.

On March 27, 2015, the Company and Intrexon (now Precigen) entered into a Second Amendment to the Exclusive Channel Partner Agreement amending the Channel Agreement, which is referred to as the ECP Amendment. The ECP Amendment modified the scope of the parties’ collaboration under the Channel Agreement in connection with the Ares Trading Agreement, which the Company and Intrexon (now Precigen) entered into with Ares Trading, on March 27, 2015. The ECP Amendment provided that Intrexon (now Precigen) will pay to the Company 50% of all payments that Precigen receives for upfronts, milestones and royalties under the Ares Trading Agreement (Note 7). The Amendment also reduces Intrexon’s aggregate commitment under a Stock Purchase Agreement that the parties executed in connection with the initial Channel Agreement to purchase the Company’s common stock from $50.0 million to $43.5 million, which has been satisfied.

On June 29, 2015, the Company re-purchased 3,711 shares of common stock from Intrexon, at a discount of 5% to the closing price of the Company’s common stock on the date of purchase, which represented fractional shares that resulted from Intrexon’s special stock dividend of the Company’s shares to Intrexon’s shareholders, for $34 thousand. On January 8, 2016, the Company re-purchased an additional 168 shares of common stock from Intrexon for $2 thousand at the same terms as the previous share purchase.

On September 28, 2015, the Company entered into the GvHD Agreement with Precigen, whereby the Company was granted the right to use Precigen’s technology directed towards in vivo expression of biologics to research, develop and commercialize products for use in the treatment or prevention of graft-versus-host disease, or GvHD (Note 7). The Company paid Precigen a technology access fee of $10.0 million in cash in October 2015 and agreed to reimburse Precigen for all research and development costs under the GvHD Agreement.

On June 29, 2016, the Company entered into the 2016 ECP Amendment, with Intrexon (now Precigen), amending the Channel Agreement, and the 2016 GvHD Amendment, amending their existing Exclusive Channel Collaboration Agreement, effective September 28, 2015, which the Company refers to as the GvHD Agreement. The 2016 ECP Amendment reduced the royalty percentage that the Company will pay to Intrexon (now Precigen) under the Channel Agreement on a quarterly basis from 50% to 20% of net profits derived in that quarter from the sale of ZIOPHARM Products (as defined in the Channel Agreement), calculated on a ZIOPHARM Product-by-ZIOPHARM Product basis, subject to certain expense allocations and other offsets provided in the Channel Agreement. The 2016 GvHD Amendment reduced the royalty percentage that the Company would pay to Intrexon (now Precigen) under the GvHD Agreement on a quarterly basis from 50% to 20% of net profits derived in that quarter from the sale of Products (as defined in the GvHD Agreement), subject to certain expense allocations and other offsets provided in the GvHD Agreement. The reductions in the royalty percentages provided by the 2016 ECP Amendment and the 2016 GvHD Amendment do not apply to sublicensing revenue or royalties under the Channel Agreement and GvHD Agreement, nor do they apply to any royalties or other payments made with respect to sublicensing revenue from the Company’s existing collaboration with Merck Serono, the biopharmaceutical business of Merck KGaA.

In consideration for the execution and delivery of the 2016 ECP Amendment and the 2016 GvHD Amendment, the Company issued Intrexon 100,000 shares of its Series 1 preferred stock. Each share of the Company’s Series 1 preferred stock has a stated value of $1,200, subject to appropriate adjustment in the event of any stock dividend, stock split, combination or other recapitalization, and certain other rights, preferences, privileges and obligations (Note 8). The holders of the shares of Series 1 preferred stock are entitled to receive a monthly dividend, payable in additional shares of Series 1 preferred stock, equal to $12.00 per preferred share held by such holder per month divided by the stated value of the preferred shares, rounded down to the nearest whole share.

During the year ended December 31, 2017, the Company issued an aggregate of 13,460 shares of Series 1 preferred stock to Intrexon, the holder of all of the outstanding shares of the Company’s Series 1 preferred stock, as monthly dividend payments. The Company recorded such shares of Series 1 preferred stock at a fair value of $18.9 million, which is a component of temporary equity and recorded a loss on the change of the derivative liabilities in the amount of $1.3 million. See Notes 4 and 8 for additional discussion regarding the accounting for and valuation of these derivative financial instruments.

During the years ended December 31, 2017, 2016, and 2015, the Company expensed $21.4 million, $22.2 million, and $16.3 million, respectively, for services performed by Intrexon. As of December 31, 2017 and 2016, the Company recorded $6.8 million and $3.4 million, respectively, in current liabilities on its balance sheet for amounts due to Intrexon.

Collaboration with Precigen and MD Anderson

On January 13, 2015, the Company, together with Intrexon (now Precigen), entered into a license agreement with MD Anderson, which is referred to as the MD Anderson License. Pursuant to the MD Anderson License, the Company and Precigen hold an exclusive, worldwide license to certain technologies owned and licensed by MD Anderson, including technologies relating to novel CAR⁺ T-cell therapies arising from the laboratory of Laurence Cooper, M.D., Ph.D., who is now the Company’s Chief Executive Officer and was formerly a professor of pediatrics at MD Anderson and now currently a visiting scientist under that institution’s policies, as well as either co-exclusive or non-exclusive licenses under certain related technologies. In partial consideration for entering into the MD Anderson License, the Company issued MD Anderson an aggregate of 11,722,163 shares of common stock for which the Company incurred a $67.3 million charge recorded in 2015. The Company has determined that the rights acquired in the MD Anderson License represent in-process research and development with no alternative future use. During the year ending December 31, 2017, the Company made four quarterly payments totaling $13.0 million, bringing the total aggregate payments to $39.2 million under this arrangement. Subsequent to the balance sheet date, the Company made the final payment of $2.7 million bringing our total prepayment to $34.6 million for programs to be conducted at MD Anderson.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Commitments and Contingencies

Operating Leases

Prior to December 31, 2012, the Company entered into an operating lease in New York, NY for office space. In accordance with this agreement, the Company entered into a letter of credit in the amount of $388 thousand, naming the Company’s landlord as beneficiary. In January 2012, the Company amended the lease agreement, adding additional office space. The collateral for the letter of credit is restricted cash and recorded in other current assets on the balance sheet as of December 31, 2017. The collateral for the letter of credit was recorded in other current assets on the balance sheet as of December 31, 2016. The lease for office space in New York, NY expires in October 2018.

On October 17, 2013, the Company entered into a sublease agreement to lease all of its New York office space to a subtenant. The Company remains primarily liable to pay rent on the original lease. The Company recorded a loss on the sublease in the amount of $729 thousand for the year ended December 31, 2013, representing the remaining contractual obligation of $2.3 million, less $1.6 million in payments from its subtenant. The Company continues to maintain the $388 thousand letter of credit in respect of the New York office space and recorded in other current assets on the balance sheets.

Prior to December 31, 2012, the Company entered into separate operating lease agreements for various spaces in a building in Boston, MA. In June 2012, the Company re-negotiated a master lease for the Company’s Boston office space to incorporate all three lease agreements under the same master agreement, which was originally set to expire in August 2016. On December 21, 2015 and April 15, 2016, the Company renewed the sublease for the Company’s corporate headquarters in Boston, MA through August 31, 2021. As of December 31, 2017, and 2016, a total security deposit of $128 thousand is included in deposits on the balance sheet.

On January 30, 2018, the Company entered into a lease agreement for office space in Houston, TX at MD Anderson. Under the terms of the Houston lease agreement, we lease approximately two hundred and ten square feet and are required to make rental payments at an average monthly rate of approximately $1 thousand through April 2021. Upon signing the lease agreement, the company expensed approximately $40 thousand for rent expense for the period beginning in May 2015 through December 2017. The $40 thousand for rent expense incurred from May 2015 through December 2017, and all future rent expense incurred in Houston, will be deducted from our prepayment at MD Anderson described in the license agreement section below.

Future net minimum lease payments under operating leases as of December 31, 2017 are as follows (in thousands):


2018		1,129
2019		723
2020		736
2021		489
2022 and beyond		—

		3,077
Less: contractual sublease income		(278	)

Future minimum lease payments, net	$	2,799

Total rent expense was approximately $0.7 million, $0.3 million, and $1.0 million for the years ended December 31, 2017, 2016, and 2015, respectively.

The Company records rent expense on a straight-line basis over the term of the lease. Accordingly, the Company has recorded a liability for deferred rent at December 31, 2017 and 2016 of $145 thousand ($141 thousand current and $1 thousand long-term) and $281 thousand ($155 thousand current and $126 thousand long-term) respectively, which is recorded in deferred rent on the balance sheet.

License Agreements

Exclusive Channel Partner Agreement with Precigen for the Cancer Programs

On January 6, 2011, the Company entered into the Channel Agreement with Intrexon (now Precigen), that governs a “channel partnering” arrangement in which the Company uses Precigen’s technology to research, develop and commercialize products in which DNA is administered to humans for expression of anti-cancer effectors for treatment or prophylaxis of cancer, which the Company collectively refers to as the Cancer Program. This Channel Agreement establishes committees comprising representatives of us and Precigen that govern activities related to the Cancer Program in the areas of project establishment, chemistry, manufacturing and controls, clinical and regulatory matters, commercialization efforts and intellectual property.

The Channel Agreement grants us a worldwide license to use patents and other intellectual property of Precigen in connection with the research, development, use, importing, manufacture, sale, and offer for sale of products involving DNA administered to humans for expression of anti-cancer effectors for the purpose of treatment or prophylaxis of cancer, which are collectively referred to as the Ziopharm Products. Such license is exclusive with respect to any clinical development, selling, offering for sale or other commercialization of Ziopharm Products, and otherwise is non-exclusive. Subject to limited exceptions, the Company may not sublicense these rights without Precigen’s written consent.

Under the Channel Agreement, and subject to certain exceptions, the Company is responsible for, among other things, the performance of the Cancer Program, including the development, commercialization and certain aspects of manufacturing of Ziopharm Products. Precigen is responsible for establishing manufacturing capabilities and facilities for the bulk manufacture of products developed under the Cancer Program, certain other aspects of manufacturing and costs of discovery-stage research with respect to platform improvements and costs of filing, prosecution and maintenance of Precigen’s patents.

After the 2016 Exclusive Channel Partner (ECP) Amendment, discussed below, and subject to certain expense allocations and other offsets provided in the Channel Agreement, the Company is obligated to pay Precigen on a quarterly basis 20% of net profits derived in that quarter from the sale of Ziopharm Products, calculated on a Ziopharm Product-by- Ziopharm Product basis. The Company likewise agreed to pay Precigen on a quarterly basis 50% of revenue obtained in that quarter from a sublicensor in the event of a sublicensing arrangement. In addition, in partial consideration for each party’s execution and delivery of the Channel Agreement, the Company entered into a stock purchase agreement with Precigen.

Upon termination of the Channel Agreement, the Company may continue to develop and commercialize any Ziopharm Product that, at the time of termination:

•

Is being commercialized by us;

•

Has received regulatory approval;

•

Is a subject of an application for regulatory approval that is pending before the applicable regulatory authority; or

•

Is the subject of at least an ongoing Phase 2 clinical trial (in the case of a termination by Precigen due to an uncured breach or a voluntary termination by us), or an ongoing Phase 1 clinical trial in the field (in the case of a termination by us due to an uncured breach or a termination by Precigen following an unconsented assignment by us or its election not to pursue development of a Superior Therapy (as defined in the Channel Agreement)).

With respect to these “retained” Ziopharm Products, the Company’s obligation to pay 20% of net profits derived from the sale of Ziopharm Products and 50% of revenue derived from a sublicensor will survive termination of the Channel Agreement.

Amendment of Collaborations with Precigen

On March 27, 2015, the Company, together with Intrexon, now Precigen, entered into an ECP Amendment, amending the Channel Agreement. The ECP Amendment modifies the scope of the parties’ collaboration under the Channel Agreement in connection with the Ares Trading Agreement discussed below. Pursuant to the ECP Amendment, the chimeric antigen receptor T-cell products to be developed and commercialized pursuant to the Ares Trading Agreement shall be included within the Precigen/ Ziopharm collaboration under the Channel Agreement. The ECP Amendment provides that Precigen will pay us fifty percent of all payments Precigen receives for upfronts, milestones and royalties under the Ares Trading Agreement.

On June 29, 2016, the Company entered into (1) the 2016 ECP Amendment with Intrexon (now Precigen), amending the Channel Agreement, and (2) the 2016 GvHD Amendment, amending the Exclusive Channel Collaboration Agreement the Company entered into with Intrexon (now Precigen) in September 2015, or the GvHD Agreement. The 2016 ECP Amendment reduced the royalty percentage that the Company will pay to Precigen under the Channel Agreement on a quarterly basis from 50% to 20% of net profits derived in that quarter from the sale of Ziopharm Products, calculated on a Ziopharm Product-by- Ziopharm Product basis, subject to certain expense allocations and other offsets provided in the Channel Agreement. The 2016 GvHD Amendment reduced the royalty percentage that the Company would pay to Precigen under the GvHD Agreement on a quarterly basis from 50% to 20% of net profits derived in that quarter from the sale of Products (as defined in the GvHD Agreement), subject to certain expense allocations and other offsets provided in the GvHD Agreement. The reductions in the royalty percentages provided by the 2016 ECP Amendment and the 2016 GvHD Amendment do not apply to sublicensing revenue or royalties under the Channel Agreement and GvHD Agreement, nor do they apply to any royalties or other payments made with respect to sublicensing revenue from the existing collaboration with Ares Trading S.A., or Ares Trading, a subsidiary of the biopharmaceutical business of Merck KGaA. The Company has recently announced the decision to stop pursuing the development of engineered cell therapy strategies for targeted treatment of GvHD. The Company has reverted the rights under the GvHD Agreement back to Precigen [and are in the process of winding down the related activities].

In consideration for the execution and delivery of the 2016 ECP Amendment and the 2016 GvHD Amendment, the Company agreed to issue to Intrexon 100,000 shares of its Series 1 preferred stock. Each share of Series 1 preferred stock has a stated value of $1,200, subject to appropriate adjustment in the event of any stock dividend, stock split, combination or other recapitalization, and certain other rights, preferences, privileges and obligations (see Note 9 to the accompanying financial statements).

Exclusive Channel Collaboration Agreement with Precigen for GvHD

On September 28, 2015, the Company entered into the GvHD Agreement with Intrexon (now Precigen), whereby the Company would use Precigen’s technology directed towards in vivo expression of effectors to research, develop and commercialize products for use in the treatment or prevention of GvHD. The GvHD Agreement granted us a worldwide license to use specified patents and other intellectual property of Precigen in connection with the research, development, use, importing, manufacture, sale, and offer for sale of products developed under the GvHD Agreement.

The Company paid Intrexon a technology access fee of $10.0 million in cash in October 2015 and agreed to reimburse Intrexon for all related research and development costs pursuant to the GvHD Agreement. The Company has determined that the rights acquired in the GvHD Agreement represent in-process research and development with no alternative future use. Accordingly, the Company recorded a charge of $10.0 million to research and development expense in September 2015.

As a result of an in-depth review of the Company’s research and development portfolio, the determination was made that the pursuit of GvHD as an indication was not a material part of its corporate strategy and therefore have decided to stop pursuing the development of engineered cell therapy strategies, used either separately or in combination, for targeted treatment of GvHD. The Company has reverted the rights under the GvHD program back to Precigen [and are in the process of winding down the related activities]. The Company made this decision to focus its efforts and resources on the development of the Controlled IL-12 and Sleeping Beauty platforms for the treatment of oncology indications.

License Agreement—The University of Texas MD Anderson Cancer Center

On January 13, 2015, the Company, together with Intrexon (now Precigen), entered into a License Agreement, or the MD Anderson License, with The University of Texas MD Anderson Cancer Center, or MD Anderson. Pursuant to the MD Anderson License, the Company, together with Precigen, hold an exclusive, worldwide license to certain technologies owned and licensed by MD Anderson including technologies relating to novel chimeric antigen receptor, or CAR, T-cell therapies, non-viral gene transfer systems, genetic modification and/or propagation of immune cells and other cellular therapy approaches, Natural Killer, or NK Cells, and T-cell receptors, or TCRs, arising from the laboratory of Laurence Cooper, M.D., Ph.D., who became the Company’s Chief Executive Officer in May 2015 and was formerly a tenured professor of pediatrics at MD Anderson and is now currently a visiting scientist under that institution’s policies, as well as either co-exclusive or non-exclusive licenses under certain related technologies.

Pursuant to the terms of the MD Anderson License, MD Anderson received consideration consisting of $50.0 million in shares of common stock (or 10,124,561 shares), and $50.0 million in shares of Intrexon’s common stock, in each case based on a trailing 20 day volume weighted average of the closing price the Company’s and Intrexon’s common stock ending on the date prior to the announcement of the entry into the MD Anderson License, collectively referred to as the License Shares, pursuant to the terms of the License Shares Securities Issuance Agreement described below. The License Shares were issued to MD Anderson on March 11, 2015, pursuant to the terms of the MD Anderson License.

On January 9, 2015, in order to induce MD Anderson to enter into the MD Anderson License on an accelerated schedule, the Company, together with Intrexon entered into a letter agreement, or the Letter Agreement, pursuant to which MD Anderson received consideration of $7.5 million in shares of common stock (or 1,597,602 shares), and $7.5 million in shares of Intrexon’s common stock, in each case based on a trailing 20-day volume-weighted average of the closing price of the Company’s and Intrexon’s common stock ending on the date prior to the execution of the Letter Agreement, collectively referred to as the Incentive Shares, in the event that the MD Anderson License was entered into on January 14, 2015. The Incentive Shares were issued to MD Anderson on March 11, 2015, pursuant to the terms of the Incentive Shares Securities Issuance Agreement described below.

On August 17, 2015, the Company, Intrexon (now Precigen) and MD Anderson entered into a research and development agreement, or the Research and Development Agreement, to formalize the scope and process for the transfer by MD Anderson, pursuant to the terms of the MD Anderson License, of certain existing research programs and related technology rights, as well as the terms and conditions for future collaborative research and development of new and ongoing research programs.

Pursuant to the Research and Development Agreement, the Company, Intrexon (now Precigen) and MD Anderson have agreed to form a joint steering committee that will oversee and manage the new and ongoing research programs. As provided under the MD Anderson License, the Company provided funding for research and development activities in support of the research programs under the Research and Development Agreement for a period of three years and in an amount of no less than $15.0 million and no greater than $20.0 million per year. During the twelve months ended December 31, 2017, the Company made payments in the aggregate amount of $13.0 million to MD Anderson compared to $15.0 million during the twelve months ended December 31, 2016. The decrease in cash paid to MD Anderson during 2017 is a result of approved expenditures incurred by us being deducted from the April, July, and October quarterly payments. As of December 31, 2017, MD Anderson had used $7.3 million to offset costs incurred pursuant to the MD Anderson License and the Research and Development Agreement. The net balance of cash resources on hand at MD Anderson is $31.9 million, of which $18.5 million is included in other current assets and the remaining $13.4 million is included in non-current assets at December 31, 2017. Subsequent to the balance sheet date, the final payment to MD Anderson was made in January 2018 for $2.7 million.

The term of the MD Anderson License expires on the last to occur of (a) the expiration of all patents licensed thereunder, or (b) the twentieth anniversary of the date of the MD Anderson License; provided, however, that following the expiration of the term of the MD Anderson License, the Company, together with Precigen, shall then have a fully-paid up, royalty free, perpetual, irrevocable and sublicensable license to use the licensed intellectual property thereunder. After ten years from the date of the MD Anderson License and subject to a 90-day cure period, MD Anderson will have the right to convert the MD Anderson License into a non-exclusive license if the Company and Precigen are not using commercially reasonable efforts to commercialize the licensed intellectual property on a case-by-case basis. After five years from the date of the MD Anderson License and subject to a 180-day cure period, MD Anderson will have the right to terminate the MD Anderson License with respect to specific technology(ies) funded by the government or subject to a third-party contract if the Company and Precigen are not meeting the diligence requirements in such funding agreement or contract, as applicable. MD Anderson may also terminate the agreement with written notice upon material breach by us and Precigen, if such breach has not been cured within 60 days of receiving such notice. In addition, the MD Anderson License will terminate upon the occurrence of certain insolvency events for both us and Precigen and may be terminated by the mutual written agreement of us, Precigen and MD Anderson.

In connection with the MD Anderson License and the issuance of the License Shares and the Incentive Shares, on January 13, 2015, the Company, together with MD Anderson, entered into a Registration Rights Agreement, or the Registration Rights Agreement, pursuant to which the Company agreed to file a “resale” registration statement, or the Registration Statement, registering the resale of the License Shares, the Incentive Shares and any other shares of the common stock held by MD Anderson on the date that the Registration Statement is filed. Under the terms of the Registration Rights Agreement, the Company is obligated to maintain the effectiveness of the Registration Statement until all securities therein are sold or are otherwise can be sold pursuant to Rule 144, without any restrictions. A prospectus supplement under the Company’s already effective registration statement on Form S-3 (File No. 333-201826) was filed on April 1, 2015 in satisfaction of its obligations under the Registration Rights Agreement.

The Company determined that the rights acquired in the MD Anderson License represented in process research and development with no alternative future use. Accordingly, the Company recorded a charge of $67.3 million to research and development expense in 2015, representing the fair value of the 11,722,163 shares of its common stock on the date the MD Anderson License was executed.

Ares Trading License and Collaboration Agreement

On March 27, 2015, the Company, together with Intrexon (now Precigen), signed a worldwide License and Collaboration Agreement, or the Ares Trading Agreement, with Ares Trading S.A., or Ares Trading, a subsidiary of the biopharmaceutical business of Merck KGaA, Darmstadt, Germany, through which the parties established a collaboration for the research and development and commercialization of certain products for the prophylactic, therapeutic, palliative or diagnostic use for cancer in humans.

Under the collaboration, Ares Trading has elected two CAR⁺ T targets for which the Company will perform certain research activities that will, in part, be funded by Ares Trading. Once these candidates reach investigational new drug, or IND, stage, the programs will be transferred to Ares Trading for clinical development and commercialization. The Company is expected to perform multiple preclinical development programs, each consisting of the development of one product candidate, pursuant to the agreement. The Company, together with Precigen, will also independently conduct research and development on other CAR⁺ T candidates, with Ares Trading having the opportunity during clinical development to opt-in to these candidates for additional payments to us and Precigen.

Precigen is entitled to receive $5.0 million, from Ares Trading, payable in equal quarterly installments over two years for each identified product candidate, which will be used to fund discovery work. The Company is responsible for costs exceeding the quarterly installments and all other costs of the preclinical research and development. For the twelve months ended December 31, 2017, the Company has expensed $1.6 million under the Ares Trading Agreement, respectively.

Ares Trading paid a non-refundable upfront fee of $115.0 million to Intrexon as consideration for entry into the Ares Trading Agreement. Pursuant to the ECP Amendment, the Company was entitled to receive 50% of the upfront fee, or $57.5 million, which was received from Intrexon in July 2015.

The Ares Trading Agreement provides for up to $60.0 million in development milestone payments, up to $148.0 million in regulatory milestone payments and up to $205.0 million in commercial milestone payments for each product candidate. Development milestone payments are triggered upon initiation of a defined phase of clinical research for a product candidate. Regulatory milestone payments are triggered upon approval to market a product candidate by the FDA, or other global regulatory authorities. Commercial milestone payments are triggered when an approved pharmaceutical product reaches certain defined levels of net sales by the licensee. The Ares Trading Agreement also provides for up to $50.0 million of one-time payments upon the achievement of certain technical milestones evidenced by the initiation of a defined phase of clinical research. All development, regulatory and technical milestones are considered substantive based on the contingent nature of the milestone, specifically reviewing factors such as the scientific, clinical, regulatory, commercial and other risks that must be overcome to achieve the milestone as well as the level of effort and investment required. Accordingly, such amounts will be recognized as revenue in full in the period in which the associated milestone is achieved, assuming all other revenue recognition criteria are met. All commercial milestones will be accounted for in the same manner as royalties and recorded as revenue upon achievement of the milestone, assuming all other revenue recognition criteria are met. The next potential milestone payment that Precigen could be entitled to receive under the Ares Trading Agreement is a $15.0 million substantive milestone for the initiation of a Phase 1 clinical trial. In addition, to the extent any of the product candidates licensed by Ares Trading are commercialized, Precigen would be entitled to receive royalties ranging from the lower-single digits to the low-teens of net sales derived from the sale of products developed under agreement. Precigen will pay 50% of all milestone and royalty payments that it receives under the Ares Trading Agreement to us pursuant to the ECP Amendment.

The term of the Ares Trading Agreement commenced in May 2015 and may be terminated by either party in the event of a material breach as defined in the agreement and may be terminated voluntarily by Ares Trading upon 90 days written notice to us.

The Company considered FASB Accounting Standards Codification 605-25, Multiple-Element Arrangements, in evaluating the appropriate accounting for the Ares Trading Agreement. In accordance with this guidance, the Company identified the license and research and development services as the deliverables in the arrangement. The Company concluded that the license does not have standalone value independent from the research and development services. Accordingly, the Ares Trading Agreement is accounted for by us as a single unit of accounting. The $57.5 million upfront payment received by us was recorded as deferred revenue and is being recognized over the estimated period of performance of the research and development services which are currently estimated to be nine years, beginning with the commencement of the research and development services. During the three and twelve months ended December 31, 2017 and 2016, the Company recognized $1.6 million, each quarter, of revenue related to the Ares Trading Agreement. As of December 31, 2017, the remaining balance of deferred revenue associated with the upfront payment is $41.5 million, of which $6.4 million is current and $35.1 million is classified as long-term. As of December 31, 2016, the remaining balance of deferred revenue associated with the upfront payment was $47.9 million, of which $6.4 million was current and $41.5 million was classified as long term.

Patent and Technology License Agreement—The University of Texas MD Anderson Cancer Center and the Texas A&M University System

On August 24, 2004, the Company entered into a patent and technology license agreement with MD Anderson and the Texas A&M University System, which the Company refers to, collectively, as the Licensors. Under this agreement, were granted an exclusive, worldwide license to rights (including rights to U.S. and foreign patent and patent applications and related improvements and know-how) for the manufacture and commercialization of two classes of organic arsenicals (water- and lipid-based) for human and animal use. The class of water-based organic arsenicals includes darinaparsin.

The Company issued options to purchase 50,222 shares outside of its stock option plans following the successful completion of certain clinical milestones, of which 37,666 shares have vested. The remaining 12,556 shares vested upon enrollment of the first patient in a multi-center pivotal clinical trial i.e. a human clinical trial intended to provide the substantial evidence of efficacy necessary to support the filing of an approvable New Drug Application, or NDA. An expense of $87 thousand was charged to research and development expense for the vesting event which occurred in March 2016. This trial was initiated by Solasia Pharma K.K., or Solasia, on March 28, 2016 and triggered a $1.0 million milestone payment to us from Solasia which was received in May 2016. An equivalent of $1.0 million milestone payment was subsequently made to MD Anderson and reported net. In addition, the Licensors are entitled to receive certain milestone payments. In addition, the Company may be required to make additional payments to the Licensors (as defined in the MD Anderson License) upon achievement of certain other milestones in varying amounts which, on a cumulative basis could total up to an additional $4.5 million. In addition, the Licensors are entitled to receive single digit percentage royalty payments on sales from a licensed product and will also be entitled to receive a portion of any fees that the Company may receive from a possible sublicense under certain circumstances.

Collaboration Agreement with Solasia Pharma K.K.

On March 7, 2011, the Company entered into a License and Collaboration Agreement with Solasia. Pursuant to the License and Collaboration Agreement, the Company granted Solasia an exclusive license to develop and commercialize darinaparsin in both intravenous and oral forms and related organic arsenic molecules, in all indications for human use in a pan-Asian/Pacific territory comprising Japan, China, Hong Kong, Macau, Republic of Korea, Taiwan, Singapore, Australia, New Zealand, Malaysia, Indonesia, Philippines and Thailand.

As consideration for the license, the Company received an upfront payment of $5.0 million to be used exclusively for further clinical development of darinaparsin outside of the pan-Asian/Pacific territory and will be entitled to receive additional payments of up to $32.5 million in development-based milestones and up to $53.5 million in sales-based milestones. The Company will also be entitled to receive double digit royalty payments from Solasia based upon net sales of licensed products in the applicable territories, once commercialized, and a percentage of sublicense revenues generated by Solasia. The $5.0 million upfront payment received in March 2011 was amortized over the period of the research and development effort, which was completed in March 2016.

On July 31, 2014, the Company entered into an amendment and restatement of the License and Collaboration Agreement granting Solasia an exclusive worldwide license to develop and commercialize darinaparsin, and related organoarsenic molecules, in both intravenous and oral forms in all indications for human use. In exchange, the Company will be eligible to receive from Solasia development- and sales-based milestones, a royalty on net sales of darinaparsin, once commercialized, and a percentage of any sublicense revenues generated by Solasia.

Solasia will be responsible for all costs related to the development, manufacturing and commercialization of darinaparsin. The Company’s Licensors, as defined in the agreement, will receive a portion of all milestone and royalty payments made by Solasia to us in accordance with the terms of the license agreement with the Licensors.

On March 28, 2016, Solasia initiated a multi-center pivotal clinical trial intended to provide substantial evidence of efficacy necessary to support the filing of an application for an NDA for darinaparsin in certain of the territories assigned to Solasia. The initiation of the trial on March 28, 2016 triggered a $1.0 million milestone payment from Solasia to us which was received in May 2016. The Company subsequently made an equivalent payment to MD Anderson as the ultimate licensor of darinaparsin (see above).

License Agreement with Baxter Healthcare S.A.

On November 3, 2006, the Company entered into a definitive Asset Purchase Agreement for indibulin and a License Agreement to proprietary nanosuspension technology with affiliates of Baxter Healthcare S.A. The purchase included the entire indibulin intellectual property portfolio as well as existing drug substance and capsule inventories. The terms of the Asset Purchase Agreement included an upfront cash payment and an additional payment for existing inventory. During the year ending December 31, 2017, the Company made the final payment of $250 thousand under the asset agreement. The Company are not actively pursuing the development of indibulin.

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

Income Taxes

There is no provision for income taxes because the Company has incurred operating losses since inception. The reported amount of income tax expense for the years differs from the amount that would result from applying domestic federal statutory tax rates to pretax losses primarily because of the changes in the valuation allowance. Significant components of the Company’s deferred tax assets at December 31, 2017 and 2016 are as follows:


	December 31,
(in thousands)	2017			2016
Net operating loss carryforwards	$	89,098		$	100,790
Start-up and organizational costs		37,488			59,360
Research and development credit carryforwards		32,395			34,845
Stock compensation		1,330			2,014
Capitalized acquisition costs		5,822			9,389
Deferred revenue		11,126			18,636
Depreciation		136			227
Other		993			1,537

		178,388			226,798
Less valuation allowance		(178,388	)		(226,798	)

Effective tax rate	$	—		$	—

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amount of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. At December 31, 2017, the Company has aggregate net operating loss carryforwards for federal tax purposes of approximately $342 million and $299 million for Federal and state purposes, respectively, available to offset future federal and state taxable income to the extent permitted under the Internal Revenue Code, or IRC, expiring in varying amounts through 2037. Additionally, the Company has approximately $35 million of research and development credits at December 31, 2017, expiring in varying amounts through 2037, which may be available to reduce future taxes.

In March 2016, the FASB issued ASU No. 2016-09, “Improvements to Employee Share-Based Payment Accounting” (ASU 2016-09), which is intended to simplify several aspects of accounting for share-based payment transactions, including the income tax effects, statutory withholding requirements, forfeitures, and classification on the statement of cash flows. ASU 2016-09 is effective for annual reporting periods after December 15, 2016, including interim reporting periods within each annual reporting period. The Company adopted this standard on January 1, 2017. The update revises requirements in the following areas: minimum statutory withholding, accounting for income taxes, and forfeitures. Prior to adoption, the Company recognized share-based compensation, net of estimated forfeitures, over the vesting period of the grant. Upon adoption of ASU 2016-09, the Company elected to change its accounting policy to recognize forfeitures as they occur. The net forfeiture policy election was adopted using a modified retrospective approach with a cumulative effect adjustment of $122 thousand recorded to retained earnings as of January 1, 2017. The update requires the Company to recognize the income tax effect of awards in the income statement when the awards vest or are settled without triggering a liability. The income tax related items had no effect on the current period presentation and the Company maintains a full valuation allowance against its deferred tax assets. As a result, an accumulated excess tax benefit of 10.2 million was recognized as a deferred tax asset with a full valuation allowance against it. Additionally, we continued to estimate the number of awards expected to be vested. The adoption had no material impact on our financial statements for the 2017 tax year or the interim periods within.

Under the IRC Section 382, certain substantial changes in the Company’s ownership may limit the amount of net operating loss carryforwards that can be utilized in any one year to offset future taxable income.

Section 382 of the IRC provides limits to which a corporation that has undergone a change in ownership (as defined) can utilize any net operating loss, or NOL, and general business tax credit carryforwards it may have. The Company commissioned an analysis to determine whether Section 382 could limit the use of its carryforwards in this manner. After completing the analysis, it was determined an ownership change had occurred in February 2007. As a result of this change, the Company’s NOL’s and general business tax credits from February 23, 2007 and prior would be completely limited under IRC Section 382. The deferred tax assets related to NOL’s and general business credits have been reduced by $11.2 million and $636 thousand, respectively, as a result of the change. The Company updated the IRC Section 382 analysis through December 31, 2014. It was determined a change of ownership occurred on February 28, 2011. The Company’s NOL’s were not further limited as a result of the change. The Company updated the IRC Section 382 analysis through December 31, 2016 and it was determined that there was no further change in ownership.

The Company has provided a valuation allowance for the full amount of these net deferred tax assets, since it is more likely than not that these future benefits will not be realized. However, these deferred tax assets may be available to offset future income tax liabilities and expenses. The valuation allowance decreased by $48.4 million in 2017 primarily due to the change in the federal tax rate, net operating loss carryforwards, and the increase in research and development credits.

Income taxes using the federal statutory income tax rate differ from the Company’s effective tax rate primarily due to non-deductible expenses related to the Company’s issuance of preferred stock along with the change in the valuation allowance on deferred tax assets.

A reconciliation of income tax expense (benefit) at the statutory federal income tax rate and income taxes as reflected in the financial statements is as follows:


	Year Ended December 31,
(in thousands)	2017			2016			2015
Federal income tax at statutory rates		34	%		34	%		34	%
State income tax, net of federal tax benefit		4	%		1	%		5	%
Research and development credits		3	%		3	%		3	%
Stock compensation		-1	%		-1	%		-1	%
Channel rights		0	%		-25	%		0	%
Research and development true-up		-7	%		0	%		0	%
Officers compensation		-2	%		0	%		0	%
Other		-3	%		0	%		0	%
Federal rate change		-124	%		0	%		0	%
Increase in valuation allowance		96	%		-12	%		-41	%

Effective tax rate		0	%		0	%		0	%

The Company adopted ASC740, “Accounting for Uncertain Tax Positions” on January 1, 2007. ASC740 clarifies the accounting for uncertainty in income taxes recognized in an enterprise’s financial statements in accordance with FASB Statement No. 109, “Accounting for Income Taxes.” ASC 740 prescribes a recognition threshold and measurement of a tax position taken or expected to be taken in a tax return. The Company did not establish any additional reserves for uncertain tax liabilities upon adoption of ASC 740. A summary of the company’s adjustments to its uncertain tax positions in the years ended December 31, 2017, 2016, and 2015 are as follows:


(in thousands)
Balance at December 31, 2014	$	238
Increase/Decrease for tax positions related to the current year		—
Increase/Decrease for tax positions related to prior years		—
Decrease for settlements with applicable taxing authorities		—
Decrease for previous year’s lapses of statute of limitations		(20	)
Decrease for impact of §382 limitations		(218	)
Decrease for lapses of statute of limitations		—

Balance at December 31, 2015	$	—
Increase/Decrease for tax positions related to the current year		—
Increase/Decrease for tax positions related to prior years		—
Decreases for settlements with applicable taxing authorities		—
Decrease for lapses of statute of limitations		—

Balance at December 31, 2016	$	—
Increase/Decrease for tax positions related to the current year		—
Increase/Decrease for tax positions related to prior years		—
Decrease for settlements with applicable taxing authorities		—
Decrease for lapses of statute of limitations		—

Balance at December 31, 2017	$	—

The Company has not recognized any interest and penalties in the statement of operations because of the Company’s net operating losses and tax credits that are available to be carried forward. When necessary, the Company will account for interest and penalties related to uncertain tax positions as part of its provision for federal and state income taxes. The Company does not expect the amounts of unrecognized benefits will change significantly within the next twelve months.

The Company is currently open to audit under the statute of limitations by the Internal Revenue Service and state jurisdictions for the years ended December 31, 1999 through 2017.

The Tax Cuts and Jobs Act, or the “Tax Act,” was enacted in December 2017. The act significantly changes US tax law by, among other things, lowering US corporate income tax rates, implementing a territorial tax system, and imposing a one-time transition tax on deemed repatriated earnings of foreign subsidiaries. The Tax Act reduces the US corporate income tax rate from 35% to 21%, effective January 1, 2018. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to reverse. As a result of the reduction in the US corporate tax rate from 35% to 21% under the Tax Act, the Company revalued its ending net deferred tax assets at December 31, 2017. There was no impact as a result of the revaluation of the deferred tax assets as the calculated provisional tax benefit of approximately $67.0 million was offset by the Company’s subsequent change in valuation allowance.

The SEC staff issued Staff Accounting Bulletin (SAB 118) to address the application of US GAAP in situations when a registrant does not have the necessary information available, prepared or analyzed in reasonable detail to complete the accounting for certain income tax effects of the Tax Act and allows the registrant to record provisional amounts during the measurement period. We are in the process of analyzing the impact of the various provisions of the Tax Act. We expect to complete our analysis within the measurement period in accordance with SAB 118.

Preferred Stock and Stockholders' Equity (Deficit)

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Preferred Stock and Stockholders' Equity (Deficit)

Preferred Stock and Stockholders’ Equity (Deficit)

On April 26, 2006, the date of the Company’s annual stockholders meeting that year, the shareholders approved the adoption of an Amended and Restated Certificate of Incorporation pursuant to which the Company has 280,000,000 shares of authorized capital stock, of which 250,000,000 shares are designated as common stock (par value $.001 per share), and 30,000,000 shares are designated as preferred stock (par value $.001 per share).

Common Stock

On February 3, 2015, the Company entered into an underwriting agreement with J.P. Morgan Securities LLC, as representative of the several underwriters named therein, relating to the issuance and sale of 10,000,000 shares of our common stock. The price to the public in the offering was $8.75 per share, and the underwriters agreed to purchase the shares from the Company pursuant to the underwriting agreement at a purchase price of $8.225 per share. Under the terms of the underwriting agreement, the Company also granted the underwriters an option, exercisable for 30 days, to purchase up to an additional 1,500,000 shares of common stock at a purchase price of $8.225 per share. The offering was made pursuant to the Company’s registration statement on Form S-3 (SEC File No. 333-201826) previously filed with the SEC, and a prospectus supplement thereunder. The underwriters purchased the 10,000,000 shares and the additional 1,500,000 shares on February 9 and 17, 2015, respectively. The net proceeds from the offering were approximately $94.3 million after deducting underwriting discounts and estimated offering expenses paid by the Company.

On January 13, 2015, the Company, together with Intrexon (now Precigen), entered into the MD Anderson License. Pursuant to the terms of the MD Anderson License, MD Anderson received consideration of 11,722,163 shares of the Company’s common stock (see Note 7).

On May 11, 2017, the Company sold in an underwritten offering an aggregate of 9,708,738 shares of its common stock. The price to the investor in the offering was $5.15 per share, and the underwriters agreed to purchase the shares from the Company pursuant to the Company’s registration statement on Form S-3ASR (File No. 333-201826) previously filed with the SEC, and a prospectus supplement thereunder. The net proceeds from the offering were approximately $47.3 million after deducting underwriting commissions and estimated offering expenses payable by the Company.

Preferred Stock

The Company’s Board of Directors are authorized to designate any series of Preferred Stock, to fix and determine the variations in relative rights, preferences, privileges and restrictions as between and among such series.

On June 29, 2016, the Company entered into the 2016 ECP Amendment and 2016 GvHD Amendment with Intrexon (now Precigen) (see Note 7). In consideration for the execution and delivery of the 2016 ECP Amendment and the 2016 GvHD Amendment, the Company issued to Intrexon 100,000 shares of its newly designated Series 1 preferred stock. Each share of the Company’s Series 1 preferred stock has a stated value of $1,200, subject to appropriate adjustment in the event of any stock dividend, stock split, combination or other recapitalization. The Series 1 preferred stock has the following rights and preferences and certain other rights, preferences, privileges and obligations.

Conversion

All shares of Series 1 preferred stock shall automatically convert into shares of common stock upon the public announcement of the first approval in the United States of (i) a ZIOPHARM Product under the Channel Agreement, (ii) a Product under the GvHD Agreement or (iii) a Product under the Ares Trading Agreement, which the Company refers to as the Conversion Event Date. On the second business day following the Conversion Event Date, each of Series 1 preferred stock shall convert into a number of shares of common stock equal to the stated value of such Series 1 preferred stock, divided by the greater of (i) the volume weighted average closing price of common stock as reported by The Nasdaq Stock Market, LLC over the 20 trading days ending on the Conversion Event Date or (ii) $1.00 per share; however, without shareholder approval in accordance with the Nasdaq listing rules, the Company will not affect any conversion of the Series 1 preferred stock into shares of common stock in excess of 19.9% of the lesser of (i) the pre-transaction outstanding shares of common stock or (ii) the outstanding shares of common stock at the time of conversion. In addition, without shareholder approval in accordance with the Nasdaq listing rules, the Company will not affect any conversion of the Series 1 preferred stock into common stock to the extent that the number of shares of common stock issued in such conversion would constitute a change of control under the Nasdaq listing rules.

Dividends

The Series 1 preferred stock provides for a monthly dividend, payable in additional shares of Series 1 preferred stock, equal to $12.00 per share, per month divided by the stated value per share, or the PIK Dividend; provided, that if any shares of Series 1 preferred stock are not converted on the Conversion Event Date (discussed below), then the rate of the PIK Dividend on all remaining unconverted shares of Series 1 preferred stock shall automatically increase from $12.00 to $24.00 per share, per month.

Liquidation Preference

In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company or a change of control or sale, lease transfer or exclusive license of all or substantially all of the Company’s assets prior to the conversion of the Series 1 preferred stock into shares of common stock, then the Series 1 preferred stock will participate in the proceeds of the transaction on a pro rata basis along with common stock, treating the Series 1 preferred stock as if it had been converted into a number of shares of common stock equal to the aggregate stated value of the Series 1 preferred stock, divided by the volume weighted average closing price of common stock over the 20 trading days ending on the public announcement of such voluntary or involuntary liquidation, dissolution or winding up of the Company or change of control or sale, lease transfer or exclusive license of all or substantially all of the Company’s assets. Alternatively, the Company may redeem the Series 1 preferred stock at a redemption price equal to the pro rata amount that the Series 1 preferred stock would have received if it had been converted using the same formula.

Voting Rights

The Series 1 preferred stock does not have any voting rights except that the Company may not, without the consent of the holders of a majority of the outstanding shares of the Series 1 preferred stock, voting as a separate class, (i) amend, alter or repeal any provision of its Certificate of Incorporation in a manner that adversely affects the powers, preferences or rights of the Series 1 preferred stock in a manner that is more adverse than the effect on any other class or series of the Company’s capital stock; (ii) (A) create, or authorize the creation of, or issue or obligate itself to issue shares of, any additional class or series of the Company’s capital stock unless the same ranks junior or pari passu to the Series 1 preferred stock with respect to the distribution of assets on the liquidation, dissolution or winding up of the Company, the payment of dividends and rights of redemption, or (B) reclassify, alter or amend any existing security that is junior or pari passu to the Series 1 preferred stock with respect to the distribution of assets on the liquidation, dissolution or winding up of the Company, the payment of dividends or rights of redemption, if such reclassification, alteration or amendment would render such other security senior to the Series 1 preferred in respect of any such right, preference or privilege; or (iii) enter into any transaction (or series of related transactions) the effect of which would adversely affect the holders of the Series 1 preferred stock in a manner that is more adverse than the effect on any other class or series of capital stock.

Analysis

The Company analyzed the features of the Series 1 preferred stock and determined that the conversion option and the Company’s right to redeem the shares at liquidation are embedded derivatives that required bifurcation from the Series 1 preferred stock in accordance with FASB ASC 815, Derivatives and Hedging. The embedded derivatives were valued as described below at $0.9 million. Upon issuance of the shares on July 1, 2016 the Company recorded the fair value of the derivatives as a liability and the fair value of the Series 1 preferred stock of $118.2 million as a component of temporary equity. Furthermore, because of the temporary equity classification, the carrying value of the Series 1 preferred stock will not be accreted to redemption value unless or until its redemption becomes probable.

The fair value of the Series 1 preferred stock was estimated using a probability-weighted approach and a Monte Carlo simulation model. The fair value of the embedded derivatives was estimated using the “with” and “without” method where the preferred stock was first valued with all of its features (“with” scenario) and then without derivatives subject to the valuation analysis (“without” scenario). The fair value of the derivatives was then estimated as the difference between the fair value of the preferred stock in the “with” scenario and the preferred stock in the “without” scenario. The model also takes into account, management estimates of clinical success/failure based upon market studies and probability of potential conversion and liquidation events. If these estimates were different, the valuations would change, and that change could be material. Inputs to the models included the following:


Risk-free interest rate		1.04	%
Expected dividend rate		0
Expected volatility		70.50	%
Preferred stock conversion limit—percentage of outstanding common stock		19.90	%
Preferred conversion floor price	$	1.00

During the year ended December 31, 2017, the Company issued an aggregate of 13,460 shares of Series 1 preferred stock to Intrexon, the holder of all of the outstanding shares of its Series 1 preferred stock, as monthly dividend payments. The Company recorded such shares of Series 1 preferred stock at a fair value of $18.9 million, which is a component of temporary equity and recorded a loss on the change in fair value of the derivative liabilities in the amount of $1.3 million (Note 10).

Derivative Financial Instruments

12 Months Ended

Dec. 31, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Financial Instruments

10.

Derivative Financial Instruments

The Company determined that certain embedded features related to the Series 1 preferred stock are derivative financial instruments. The company values the embedded derivative financial instruments related to the Series 1 preferred stock as Level 3 financial liabilities (Note 3).

Fair values of derivative instruments to be classified as derivative liabilities on the balance sheet consist of the following:


($ in thousands)
Liability derivatives:	Balance Sheet Location		Fair Value
December 31, 2017:
Derivative liabilities		Liabilities	$	2,424

The change in the derivative liability for the year ended December 31, 2017 and 2016 consists of the following:


($ in thousands)
	Fair Value
Balance, June 30, 2016	$	694
Dividends		44
Change in fair value		124

Balance, December 31, 2016	$	862
Dividends		267
Change in fair value		1,295

Balance, December 31, 2017	$	2,424

The fair value of the Series 1 preferred stock dividends was estimated using a probability-weighted approach and a Monte Carlo simulation model. The fair value of the embedded derivatives was estimated using the “with” and “without” method where the preferred stock was first valued with all of its features (“with” scenario) and then without derivatives subject to the valuation analysis (“without” scenario). The fair value of the derivatives was then estimated as the difference between the fair value of the preferred stock in the “with” scenario and the preferred stock in the “without” scenario. The model also takes into account, management estimates of clinical success/failure based upon market studies and probability of potential conversion and liquidation events. If these estimates were different, the valuations would change, and that change could be material. Inputs to the models included the following:


	December 31,
	2017	2016
Risk-free interest rate	1.92 - 2.12%	1.04% - 1.69%
Expected dividend rate	0	0
Expected volatility	68.7 - 80.4%	70.5% - 72.70%
Preferred stock conversion limit—percentage of outstanding common stock	19.90%	19.90%
Preferred conversion floor price	$1.00	$1.00

See Notes 3 and 7 for additional discussion regarding the accounting for and valuation of these derivative financial instruments.

Stock Option Plan

12 Months Ended

Dec. 31, 2017

Text Block [Abstract]

Stock Option Plan

11.

Stock Option Plan

The Company adopted the 2012 Equity Incentive Plan, or the 2012 Plan, in May 2012, under which the Company initially reserved for the issuance of 4,000,000 shares of its common stock. The 2012 Plan was approved by the Company’s stockholders on June 20, 2012. On June 18, 2014, the date of the Company’s annual stockholders meeting, the Company’s stockholders approved an amendment to the 2012 Plan increasing the total shares reserved by 5,000,000 shares, for a total of 9,000,000 shares.

As of December 31, 2017, the Company had outstanding options issued to its employees to purchase up to 3,214,635 shares of the Company’s common stock, to its directors to purchase up to 627,500 shares of the Company’s common stock, as well as options to consultants in connection with services rendered to purchase up to 10,000 shares of the Company’s common stock.

Stock options to employees generally vest ratably in annual installments over three years, commencing on the first anniversary of the grant date and have contractual terms of ten years. Stock options to directors generally vest ratably over one or three years and have contractual terms of ten years. Stock options are valued using the Black-Scholes option pricing model and compensation is recognized based on such fair value over the period of vesting on a straight-line basis. The Company has also reserved an aggregate of 526,364 additional shares for issuance under options granted outside of the 2003 and 2012 Plans.

Proceeds from the option exercises during the years ended December 31, 2017, 2016, and 2015 amounted to $0.1 million, $0.7 million and $4.6 million respectively. The intrinsic value of these options amounted to $0.3 million, $1.5 million and $23.8 million for years ended December 31, 2017, 2016 and 2015, respectively.

Transactions under the 2012 Plan for the years ending December 31, 2017, 2016, and 2015 were as follows:


(in thousands, except share and per share data)	Number of Shares			Weighted- Average Exercise Price		Weighted- Average Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding, December 31, 2014		6,505,663		$	4.07
Granted		427,800			10.47
Exercised		(3,249,160	)		3.95
Cancelled		(202,835	)		4.36

Outstanding, December 31, 2015		3,481,468			4.96
Granted		362,800			6.40
Exercised		(234,833	)		4.57
Cancelled		(144,100	)		6.43

Outstanding, December 31, 2016		3,465,335			5.07
Granted		688,800			5.27
Exercised		(180,000	)		3.67
Cancelled		(122,000	)		6.64

Outstanding, December 31, 2017		3,852,135		$	5.12		6.47	$	1,152

Options exercisable, December 31, 2017		2,925,502		$	5.12		5.58	$	1,152

Options exercisable, December 31, 2016		2,671,835		$	4.40		5.88	$	3,383

Options available for future grant at December 31, 2017		303,928

In September 2017, the Company granted an option for 500,000 shares of its common stock, with an exercise price of $6.16 per share, which vests ratably in annual installments over three years, commencing on the first anniversary of the grant date and have contractual terms of ten years. This option was granted outside of the 2012 plan and therefore, is not included in the table above. The grant date fair value was $2.2 million. As of December 31, 2017, all 500,000 options are outstanding.

At December 31, 2017, total unrecognized compensation costs related to non-vested stock options outstanding amounted to $5.1 million. The cost is expected to be recognized over a weighted-average period of 1.73 years.

Restricted Stock

In December 2017, the Company issued 838,000 shares of restricted stock to its employees, which vest ratably in annual installments over three years, commencing on the first anniversary of the grant date. In December 2017, the Company issued 69,032 shares of restricted stock to its non-employee directors, which vest in their entirety on the one-year anniversary of the grant date. In December 2016, the Company issued 625,750 shares of restricted stock to its employees, which vest ratably in annual installments over three years, commencing on the first anniversary of the grant date. In December 2016, the Company issued 86,020 shares of restricted stock to its non-employee directors, which vest in their entirety on the one-year anniversary of the grant date. In May, June and December 2015, the Company issued 1,000,000, 50,000 and 403,083 shares of restricted stock to its employees, respectively, which vest ratably in annual installments over three years, commencing on the first anniversary of the grant date. In September and December 2015, the Company issued 4,186 and 133,305 shares of restricted stock to its non-employee directors, which vested in their entirety at December 31, 2015 and on the one-year anniversary of the grant date respectively.

In May, June and December 2017, the Company repurchased 132,000, 16,666 and 245,602 shares at average prices of $7.12, $6.11 and $4.14, respectively to cover payroll taxes. In May, June and December 2016, the Company repurchased 116,667, 6,667 and 119,873 shares at average prices of $6.86, $7.74 and $5.35, respectively to cover payroll taxes. In September and December 2015, the Company repurchased 7,669 and 16,709 shares at average prices of $11.57 and $8.31, respectively to cover payroll taxes. A summary of the status of non-vested restricted stock as of December 31, 2017, 2016 and 2015 is as follows:


	Number of Shares			Weighted-Average Grant Date Fair Value
Non-vested, December 31, 2014		144,508		$	4.70
Granted		1,590,574			9.01
Vested		(148,694	)		4.88
Cancelled		—			—

Non-vested, December 31, 2015		1,586,388			9.00
Granted		711,770			5.35
Vested		(617,666	)		8.90
Cancelled		—			—

Non-vested, December 31, 2016		1,680,492			7.49
Granted		907,032			4.14
Vested		(778,965	)		7.66
Cancelled		—			—

Non-vested, December 31, 2017		1,808,559		$	5.74

As of December 31, 2017, there was $8.2 million of total unrecognized stock-based compensation expense related to non-vested restricted stock arrangements. The expense is expected to be recognized over a weighted-average period of 1.59 years.

Employee Benefit Plan

12 Months Ended

Dec. 31, 2017

Postemployment Benefits [Abstract]

Employee Benefit Plan

12.

Employee Benefit Plan

The Company sponsors a qualified 401(k) retirement plan under which employees are allowed to contribute certain percentages of their pay, up to the maximum allowed under Section 401(k) of the IIRC. The Company may make contributions to this plan at its discretion. The Company contributed approximately $90 thousand, $75 thousand, and $47 thousand to this plan during the years ended December 31, 2017, 2016, and 2015, respectively.

Selected Quarterly Information (Unaudited)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Information (Unaudited)

13.

Selected Quarterly Information (Unaudited)

(in thousands, except per share amount)


Year Ended December 31, 2017	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
Revenue	$	1,597		$	1,597		$	1,598		$	1,597
Total operating expenses		15,562			14,611			14,676			15,033
Loss from operations		(13,965	)		(13,014	)		(13,078	)		(13,436	)
Preferred stock dividends		(4,171	)		(4,865	)		(4,903	)		(4,999	)
Net (loss) applicable to common shareholders		(19,658	)		(17,727	)		(17,604	)		(18,272	)
Loss per share, basic and diluted	$	(0.15	)	$	(0.13	)	$	(0.13	)	$	(0.12	)

Year Ended December 31, 2016	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
Revenue	$	1,969		$	1,697		$	1,598		$	1,597
Total operating expenses		14,009			132,939			12,512			12,708
Loss from operations		(12,040	)		(131,242	)		(10,914	)		(11,111	)
Preferred stock dividends		—			—			(3,591	)		(3,532	)
Net (loss) applicable to common shareholders		(12,019	)		(131,200	)		(14,445	)		(14,756	)
Loss per share, basic and diluted	$	(0.09	)	$	(1.01	)	$	(0.11	)	$	(0.11	)

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Basis of Presentation

Basis of Presentation

The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America or U.S. GAAP.

Use of Estimates

Use of Estimates

The Company’s most significant estimates and judgments used in the preparation of our financial statements are:

•

Clinical trial expenses;

•

Collaboration agreements;

•

Fair value measurements of stock-based compensation and Series 1 preferred stock (and related dividends); and

•

Income taxes.

Subsequent Events

Subsequent Events

Cash and Cash Equivalents

Cash and Cash Equivalents

Concentrations of Credit Risk

Concentrations of Credit Risk

Property and Equipment

Property and Equipment

Restricted Cash

Restricted Cash

Long-Lived Assets

Long-Lived Assets

Operating Segments

Operating Segments

Fair Value Measurements

Fair Value Measurements

•

Level 1—Quoted prices in active markets for identical assets or liabilities.

•

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Assets and liabilities measured at fair value on a recurring basis as of December 31, 2017 and 2016 are as follows:


($ in thousands)				Fair Value Measurements at Reporting Date Using
Description	Balance as of December 31, 2017			Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents	$	66,156		$	66,156	$	—	$	—

Derivative liabilities	$	(2,424	)	$	—	$	—	$	(2,424	)


($ in thousands)				Fair Value Measurements at Reporting Date Using
Description	Balance as of December 31, 2016			Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents	$	77,120		$	77,120	$	—	$	—

Derivative liabilities	$	(862	)	$	—	$	—	$	(862	)

The cash equivalents represent deposits in a short term United States treasury money market mutual fund quoted in an active market and classified as a Level 1 asset.

Revenue Recognition from Collaboration Agreements

Revenue Recognition from Collaboration Agreements

Research and Development Costs

Research and Development Costs

Income Taxes

Income Taxes

Accounting for Stock-Based Compensation

Accounting for Stock-Based Compensation


	Year ended December 31,
(in thousands)	2017		2016		2015
Research and development	$	2,401	$	2,077	$	1,403
General and administrative		6,053		6,375		6,594

Share based employee compensation expense before tax		8,454		8,452		7,997
Income tax benefit		—		—		—

Net share based employee compensation expense	$	8,454	$	8,452	$	7,997


	2017	2016	2015
Weighted average risk-free interest rate	1.85 - 2.27%	1.27 - 2.09%	1.46 - 1.93%
Expected life in years	6	6	6
Expected volatility	80.31 - 81.03%	79.15 - 82.95%	79.13 - 86.81%
Expected dividend yield	0	0	0

Net Loss Per Share

Net Loss Per Share


	December 31,
	2017		2016		2015
Stock options		4,352,135		3,465,335		3,481,468
Unvested restricted stock		1,808,559		1,680,492		1,586,388
Preferred stock		34,134,524		20,465,067		—

	40,295,218		25,610,894		5,067,856

New Accounting Pronouncements

New Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Assets and Liabilities Measured at Fair Value on Recurring Basis

Assets and liabilities measured at fair value on a recurring basis as of December 31, 2017 and 2016 are as follows:


($ in thousands)				Fair Value Measurements at Reporting Date Using
Description	Balance as of December 31, 2017			Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents	$	66,156		$	66,156	$	—	$	—

Derivative liabilities	$	(2,424	)	$	—	$	—	$	(2,424	)


($ in thousands)				Fair Value Measurements at Reporting Date Using
Description	Balance as of December 31, 2016			Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents	$	77,120		$	77,120	$	—	$	—

Derivative liabilities	$	(862	)	$	—	$	—	$	(862	)

Share-Based Compensation Expense Included in Statements of Operations

The following table presents share-based compensation expense included in the Company’s Statements of Operations:


	Year ended December 31,
(in thousands)	2017		2016		2015
Research and development	$	2,401	$	2,077	$	1,403
General and administrative		6,053		6,375		6,594

Share based employee compensation expense before tax		8,454		8,452		7,997
Income tax benefit		—		—		—

Net share based employee compensation expense	$	8,454	$	8,452	$	7,997

Assumptions for Volatility, Expected life, Dividend Yield and Risk-free Interest Rate

The assumptions for volatility, expected life, dividend yield and risk-free interest rate are presented in the table below:


	2017	2016	2015
Weighted average risk-free interest rate	1.85 - 2.27%	1.27 - 2.09%	1.46 - 1.93%
Expected life in years	6	6	6
Expected volatility	80.31 - 81.03%	79.15 - 82.95%	79.13 - 86.81%
Expected dividend yield	0	0	0

Potentially Dilutive Shares Excluded from Computation of Diluted Net Loss Per Share

The Company’s potentially dilutive shares, which include outstanding common stock options, unvested restricted stock and preferred stock, have not been included in the computation of diluted net loss per share for any of the periods presented as the result would be antidilutive. Such potential common shares at December 31, 2017, 2016, and 2015 consist of the following:


	December 31,
	2017		2016		2015
Stock options		4,352,135		3,465,335		3,481,468
Unvested restricted stock		1,808,559		1,680,492		1,586,388
Preferred stock		34,134,524		20,465,067		—

	40,295,218		25,610,894		5,067,856

Property and Equipment, net (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Component of Property and Equipment, Net

Property and equipment, net, consists of the following:


	December 31,
(in thousands)	2017			2016
Office and computer equipment	$	1,215		$	1,162
Software		913			907
Leasehold improvements		1,553			1,158
Research and development equipment		1,161			878

		4,842			4,105
Less: accumulated depreciation		(3,631	)		(3,262	)

Property and equipment, net	$	1,211		$	843

Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2017

Payables and Accruals [Abstract]

Component of Accrued Expenses

Accrued expenses consist of the following:


	December 31,
(in thousands)	2017		2016
Clinical consulting services	$	3,022	$	2,342
Preclinical services		2,210		2,693
Employee compensation		1,919		1,446
Payroll taxes and benefits		1,017		646
Manufacturing services		902		1,116
Accrued vacation		361		294
Professional services		256		488
Other consulting services		222		28
Accrued rent		—		56

Total	$	9,909	$	9,109

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Future Net Minimum Lease Payments under Operating Leases

Future net minimum lease payments under operating leases as of December 31, 2017 are as follows (in thousands):


2018		1,129
2019		723
2020		736
2021		489
2022 and beyond		—

		3,077
Less: contractual sublease income		(278	)

Future minimum lease payments, net	$	2,799

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Significant Component of Deferred Tax Assets

Significant components of the Company’s deferred tax assets at December 31, 2017 and 2016 are as follows:


	December 31,
(in thousands)	2017			2016
Net operating loss carryforwards	$	89,098		$	100,790
Start-up and organizational costs		37,488			59,360
Research and development credit carryforwards		32,395			34,845
Stock compensation		1,330			2,014
Capitalized acquisition costs		5,822			9,389
Deferred revenue		11,126			18,636
Depreciation		136			227
Other		993			1,537

		178,388			226,798
Less valuation allowance		(178,388	)		(226,798	)

Effective tax rate	$	—		$	—

Reconciliation of Income Tax Expense (Benefit)

A reconciliation of income tax expense (benefit) at the statutory federal income tax rate and income taxes as reflected in the financial statements is as follows:


	Year Ended December 31,
(in thousands)	2017			2016			2015
Federal income tax at statutory rates		34	%		34	%		34	%
State income tax, net of federal tax benefit		4	%		1	%		5	%
Research and development credits		3	%		3	%		3	%
Stock compensation		-1	%		-1	%		-1	%
Channel rights		0	%		-25	%		0	%
Research and development true-up		-7	%		0	%		0	%
Officers compensation		-2	%		0	%		0	%
Other		-3	%		0	%		0	%
Federal rate change		-124	%		0	%		0	%
Increase in valuation allowance		96	%		-12	%		-41	%

Effective tax rate		0	%		0	%		0	%

Summary of Adjustments to Uncertain Tax Position

A summary of the company’s adjustments to its uncertain tax positions in the years ended December 31, 2017, 2016, and 2015 are as follows:


(in thousands)
Balance at December 31, 2014	$	238
Increase/Decrease for tax positions related to the current year		—
Increase/Decrease for tax positions related to prior years		—
Decrease for settlements with applicable taxing authorities		—
Decrease for previous year’s lapses of statute of limitations		(20	)
Decrease for impact of §382 limitations		(218	)
Decrease for lapses of statute of limitations		—

Balance at December 31, 2015	$	—
Increase/Decrease for tax positions related to the current year		—
Increase/Decrease for tax positions related to prior years		—
Decreases for settlements with applicable taxing authorities		—
Decrease for lapses of statute of limitations		—

Balance at December 31, 2016	$	—
Increase/Decrease for tax positions related to the current year		—
Increase/Decrease for tax positions related to prior years		—
Decrease for settlements with applicable taxing authorities		—
Decrease for lapses of statute of limitations		—

Balance at December 31, 2017	$	—

Derivative Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Assumptions Used in Probability Weighted Approach and Monte Carlo Simulation Model


Risk-free interest rate		1.04	%
Expected dividend rate		0
Expected volatility		70.50	%
Preferred stock conversion limit—percentage of outstanding common stock		19.90	%
Preferred conversion floor price	$	1.00

Fair Values of Derivative Instruments to be classified as Derivative Liabilities on Balance Sheet

Fair values of derivative instruments to be classified as derivative liabilities on the balance sheet consist of the following:


($ in thousands)
Liability derivatives:	Balance Sheet Location		Fair Value
December 31, 2017:
Derivative liabilities		Liabilities	$	2,424

Change in Derivative Liability

The change in the derivative liability for the year ended December 31, 2017 and 2016 consists of the following:


($ in thousands)
	Fair Value
Balance, June 30, 2016	$	694
Dividends		44
Change in fair value		124

Balance, December 31, 2016	$	862
Dividends		267
Change in fair value		1,295

Balance, December 31, 2017	$	2,424

Series 1 Preferred Stock

Fair Value Assumptions Used in Probability Weighted Approach and Monte Carlo Simulation Model


	December 31,
	2017	2016
Risk-free interest rate	1.92 - 2.12%	1.04% - 1.69%
Expected dividend rate	0	0
Expected volatility	68.7 - 80.4%	70.5% - 72.70%
Preferred stock conversion limit—percentage of outstanding common stock	19.90%	19.90%
Preferred conversion floor price	$1.00	$1.00

Stock Option Plan (Tables)

12 Months Ended

Dec. 31, 2017

Text Block [Abstract]

Transaction under Stock Option Plan

Transactions under the 2012 Plan for the years ending December 31, 2017, 2016, and 2015 were as follows:


(in thousands, except share and per share data)	Number of Shares			Weighted- Average Exercise Price		Weighted- Average Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding, December 31, 2014		6,505,663		$	4.07
Granted		427,800			10.47
Exercised		(3,249,160	)		3.95
Cancelled		(202,835	)		4.36

Outstanding, December 31, 2015		3,481,468			4.96
Granted		362,800			6.40
Exercised		(234,833	)		4.57
Cancelled		(144,100	)		6.43

Outstanding, December 31, 2016		3,465,335			5.07
Granted		688,800			5.27
Exercised		(180,000	)		3.67
Cancelled		(122,000	)		6.64

Outstanding, December 31, 2017		3,852,135		$	5.12		6.47	$	1,152

Options exercisable, December 31, 2017		2,925,502		$	5.12		5.58	$	1,152

Options exercisable, December 31, 2016		2,671,835		$	4.40		5.88	$	3,383

Options available for future grant at December 31, 2017		303,928

Summary of Non-Vested Restricted Stock

A summary of the status of non-vested restricted stock as of December 31, 2017, 2016 and 2015 is as follows:


	Number of Shares			Weighted-Average Grant Date Fair Value
Non-vested, December 31, 2014		144,508		$	4.70
Granted		1,590,574			9.01
Vested		(148,694	)		4.88
Cancelled		—			—

Non-vested, December 31, 2015		1,586,388			9.00
Granted		711,770			5.35
Vested		(617,666	)		8.90
Cancelled		—			—

Non-vested, December 31, 2016		1,680,492			7.49
Granted		907,032			4.14
Vested		(778,965	)		7.66
Cancelled		—			—

Non-vested, December 31, 2017		1,808,559		$	5.74

Selected Quarterly Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Information


Year Ended December 31, 2017	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
Revenue	$	1,597		$	1,597		$	1,598		$	1,597
Total operating expenses		15,562			14,611			14,676			15,033
Loss from operations		(13,965	)		(13,014	)		(13,078	)		(13,436	)
Preferred stock dividends		(4,171	)		(4,865	)		(4,903	)		(4,999	)
Net (loss) applicable to common shareholders		(19,658	)		(17,727	)		(17,604	)		(18,272	)
Loss per share, basic and diluted	$	(0.15	)	$	(0.13	)	$	(0.13	)	$	(0.12	)

Year Ended December 31, 2016	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
Revenue	$	1,969		$	1,697		$	1,598		$	1,597
Total operating expenses		14,009			132,939			12,512			12,708
Loss from operations		(12,040	)		(131,242	)		(10,914	)		(11,111	)
Preferred stock dividends		—			—			(3,591	)		(3,532	)
Net (loss) applicable to common shareholders		(12,019	)		(131,200	)		(14,445	)		(14,756	)
Loss per share, basic and diluted	$	(0.09	)	$	(1.01	)	$	(0.11	)	$	(0.11	)

Organization and Going Concern - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Accumulated deficit	$ (712,442)	$ (657,997)
Cash and cash equivalents	$ 70,946	$ 81,053	$ 140,717	$ 42,803

Financings - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	May 11, 2017	Feb. 17, 2015	Feb. 09, 2015	Feb. 03, 2015
Class of Stock [Line Items]
Stock issued during period	9,708,738
Issuance & sale of common stock in public offering price per share	$ 5.15
Sale of stock price per share	$ 4.893
Net proceeds from issuance of common stock	$ 47.3
J.P. Morgan Securities Inc.
Class of Stock [Line Items]
Stock issued during period		1,500,000	10,000,000	10,000,000
Issuance & sale of common stock in public offering price per share				$ 8.75
Option granted, exercisable period				30 days
Sale of stock price per share				$ 8.225
Net proceeds from issuance of common stock		$ 94.3

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jun. 29, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2018	May 31, 2015
Summary Of Significant Accounting Policies [Line Items]
Stock based compensation expenses		$ 8,454	$ 8,452	$ 7,997
Weighted average fair value of stock option granted		$ 3.94	$ 4.43	$ 10.47
Stock Options
Summary Of Significant Accounting Policies [Line Items]
Stock based compensation expenses		$ 2,500	$ 3,000	$ 5,300
Restricted Stock
Summary Of Significant Accounting Policies [Line Items]
Stock based compensation expenses		6,000	5,500	$ 2,700
Current Assets \| Lease Obligations
Summary Of Significant Accounting Policies [Line Items]
Restricted cash		388
Other Noncurrent Assets \| Line of Credit
Summary Of Significant Accounting Policies [Line Items]
Restricted cash		104
ARES Trading License
Summary Of Significant Accounting Policies [Line Items]
Deferred revenue		$ 41,500	$ 47,900			$ 57,500
Minimum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment useful life		3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment useful life		5 years
Accumulated Deficit
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment		$ (122)
ASU 2014-09 \| Subsequent Event
Summary Of Significant Accounting Policies [Line Items]
Deferred revenue					$ 8,100
ASU 2014-09 \| Subsequent Event \| Accumulated Deficit
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment					$ (8,100)
Adjustments for New Accounting Pronouncement \| ARES Trading License
Summary Of Significant Accounting Policies [Line Items]
Transaction price allocated to performance obligations		$ 57,500
Intrexon Corporation/Precigen \| Series 1 Preferred Stock
Summary Of Significant Accounting Policies [Line Items]
Issuance of stock in a license agreement (in shares)	100,000	13,460
Number of shares converted into common stock		34,134,524
Preferred stock, conversion rate		$ 1.00

Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 66,156	$ 77,120
Derivative liabilities	(2,424)	(862)
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	66,156	77,120
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	$ (2,424)	$ (862)

Stock-Based Compensation Expense Included in Statement of Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 8,454	$ 8,452	$ 7,997
Income tax benefit	0	0	0
Net share based employee compensation expense	8,454	8,452	7,997
Research and Development Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	2,401	2,077	1,403
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 6,053	$ 6,375	$ 6,594

Fair Value of Stock Options Assumptions Using Black-Scholes Option Valuation Model (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Risk-free interest rate, Minimum	1.85%	1.27%	1.46%
Risk-free interest rate, Maximum	2.27%	2.09%	1.93%
Expected life in years	6 years	6 years	6 years
Expected volatility, Minimum	80.31%	79.15%	79.13%
Expected volatility, Maximum	81.03%	82.95%	86.81%
Expected dividend yield	0.00%	0.00%	0.00%

Potential Dilutive Shares Excluded from Computation of Diluted Net Loss Per Share (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	40,295,218	25,610,894	5,067,856
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	4,352,135	3,465,335	3,481,468
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	1,808,559	1,680,492	1,586,388
Series 1 Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	34,134,524	20,465,067

Component of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 4,842	$ 4,105
Less: accumulated depreciation	(3,631)	(3,262)
Property and equipment, net	1,211	843
Office and computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	1,215	1,162
Software
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	913	907
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	1,553	1,158
Research and development equipment
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 1,161	$ 878

Property and Equipment, net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Depreciation	$ 369	$ 290	$ 357

Component of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Clinical consulting services	$ 3,022	$ 2,342
Preclinical services	2,210	2,693
Employee compensation	1,919	1,446
Payroll taxes and benefits	1,017	646
Manufacturing services	902	1,116
Accrued vacation	361	294
Professional services	256	488
Other consulting services	222	28
Accrued rent		56
Total	$ 9,909	$ 9,109

Related Party Transactions - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands											1 Months Ended		6 Months Ended	12 Months Ended
	Jan. 13, 2018	May 11, 2017	Jun. 29, 2016	Jan. 08, 2016	Sep. 28, 2015	Jun. 29, 2015	Mar. 27, 2015	Feb. 03, 2015	Jan. 13, 2015	Jan. 06, 2011	Sep. 30, 2015	Jul. 31, 2015	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Stock issued during period		9,708,738
Commitment to purchase common stock															$ 2	$ 34
Stock buy back														$ 2,059	2	34
Company re-purchased additional shares Value															1,500	518
Change in fair value of derivative liability													$ 124	1,295	124
Research and Development Expense														45,084	157,791	$ 106,785
Research and Development Service Agreement Aggregate Quarterly Payments														13,000	$ 15,000
Research and Development Service Agreement Aggregate Quarterly Payments														$ 39,200
Subsequent Event
Related Party Transaction [Line Items]
Research and Development Service Agreement Aggregate Quarterly Payments	$ 34,600
Research and Development Service Agreement Final Payments	$ 2,700
Series 1 Preferred Stock
Related Party Transaction [Line Items]
Preferred stock, stated value													$ 1,200	$ 1,200	$ 1,200
Temporary equity, fair value														$ 18,900
License Agreement
Related Party Transaction [Line Items]
Issuance of common stock in licensing agreement (in shares)									11,722,163					11,722,163		11,722,163
Research and Development Expense														$ 67,300		$ 67,300
Intrexon Corporation/Precigen
Related Party Transaction [Line Items]
Stock issued during period								1,440,000
Percentage of commitment for payments from receipts of upfronts, milestones and royalties							50.00%
Commitment to purchase common stock							$ 43,500			$ 50,000
Stock buy back (Shares)						3,711
Stock buy back						$ 34
Share buy back discount on closing price						5.00%
Company re-purchased additional shares				168
Company re-purchased additional shares Value				$ 2
Licensing fee					$ 10,000							$ 115,000
Royalty percentage of net profit														20.00%
Amounts expensed for services incurred														$ 21,400	$ 22,200	$ 16,300
Amount due to related party, current													$ 3,400	$ 6,800	$ 3,400
Intrexon Corporation/Precigen \| Series 1 Preferred Stock
Related Party Transaction [Line Items]
Issuance of common stock in licensing agreement (in shares)			100,000											13,460
Preferred stock, stated value			$ 1,200
Dividends, preferred stock			$ 12.00
Intrexon Corporation/Precigen \| 2016 GvHD Amendment
Related Party Transaction [Line Items]
Licensing fee					$ 10,000
Research and Development Expense											$ 10,000
Intrexon Corporation/Precigen \| Quarterly Payment
Related Party Transaction [Line Items]
Royalty percentage of net profit										20.00%
Intrexon Corporation/Precigen \| Quarterly Payment \| ECP Channel Agreement \| After Amendment
Related Party Transaction [Line Items]
Royalty percentage of net profit			20.00%
Intrexon Corporation/Precigen \| Quarterly Payment \| ECP Channel Agreement \| Before Amendment
Related Party Transaction [Line Items]
Royalty percentage of net profit			50.00%
Intrexon Corporation/Precigen \| Quarterly Payment \| 2016 GvHD Amendment \| After Amendment
Related Party Transaction [Line Items]
Royalty percentage of net profit			20.00%
Intrexon Corporation/Precigen \| Quarterly Payment \| 2016 GvHD Amendment \| Before Amendment
Related Party Transaction [Line Items]
Royalty percentage of net profit			50.00%

Commitments and Contingencies - Additional Information (Detail)										1 Months Ended		3 Months Ended		12 Months Ended						32 Months Ended
	Jan. 13, 2018 USD ($)	Jan. 01, 2018 USD ($)	Jun. 29, 2016 $ / shares shares	Sep. 28, 2015 USD ($)	Jan. 13, 2015 USD ($) shares	Jan. 09, 2015 USD ($) shares	Mar. 07, 2011 USD ($)	Jan. 06, 2011	Aug. 24, 2004 Patent	Sep. 30, 2015 USD ($)	Jul. 31, 2015 USD ($)	Dec. 31, 2017 USD ($) $ / shares	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2013 USD ($)	Dec. 31, 2012	Dec. 31, 2011 USD ($)	Dec. 31, 2017 USD ($) $ / shares	Jan. 30, 2018 USD ($) ft²	Mar. 31, 2016 USD ($)	May 31, 2015 USD ($)	Dec. 31, 2014 USD ($) shares
Commitments and Contingencies Disclosure [Line Items]
Total rent expense														$ 700,000	$ 300,000	$ 1,000,000				$ 40,000
Deferred rent - current portion												$ 141,000	$ 155,000	141,000	155,000					141,000
Deferred rent-non-current portion												1,000	126,000	1,000	126,000					1,000
Deferred rent liability net												145,000	281,000	145,000	281,000					145,000
Research and Development Expense														$ 45,084,000	157,791,000	106,785,000
Research and development arrangement Terms														Pursuant to the Research and Development Agreement, the Company, Intrexon and MD Anderson have agreed to form a joint steering committee that will oversee and manage the new and ongoing research programs. As provided under the MD Anderson License, the Company will provide funding for research and development activities in support of the research programs under the Research and Development Agreement for a period of three years and in an amount of no less than $15.0 million and no greater than $20.0 million per year.
Research and Development Service Agreement Aggregate Quarterly Payments														$ 13,000,000	15,000,000
Offset costs in research and development expense														7,300,000
Cash balance												70,946,000	81,053,000	70,946,000	81,053,000	140,717,000				70,946,000				$ 42,803,000
Research and Development Service Agreement Final Payments														39,200,000
Deferred revenue - current portion												6,389,000	6,389,000	6,389,000	6,389,000					6,389,000
Deferred Revenue, long term												35,139,000	41,528,000	$ 35,139,000	41,528,000					35,139,000
Issuance of common stock in a license agreement																$ 67,285,000
The University of Texas MD Anderson Cancer Center and The Texas A & M University System
Commitments and Contingencies Disclosure [Line Items]
Milestone maximum payment																								$ 4,500,000
Number of products \| Patent									2
Options to purchase common stock \| shares														50,222
Shares vested \| shares																								37,666
The University of Texas MD Anderson Cancer Center and The Texas A & M University System \| Research and Development Expense
Commitments and Contingencies Disclosure [Line Items]
Issuance of common stock in a license agreement														$ 87,000
The University of Texas MD Anderson Cancer Center and The Texas A & M University System \| Upon enrollment of the first patient in a multi-center pivotal clinical trial
Commitments and Contingencies Disclosure [Line Items]
Shares vested \| shares																								12,556
Solasia
Commitments and Contingencies Disclosure [Line Items]
Upfront payment received							$ 5,000,000
Milestone payment received																						$ 1,000,000
Milestone Payments Payable																						$ 1,000,000
Solasia \| Development-based milestones
Commitments and Contingencies Disclosure [Line Items]
Expected Additional milestone payments to be received														32,500,000
Solasia \| Sales-based milestones
Commitments and Contingencies Disclosure [Line Items]
Expected Additional milestone payments to be received														53,500,000
Baxter Healthcare Corporation \| Upon the successful U.S. IND application for indibulin
Commitments and Contingencies Disclosure [Line Items]
Installment payments														$ 250,000
License Agreement
Commitments and Contingencies Disclosure [Line Items]
Issuance of common stock in licensing agreement, shares \| shares					11,722,163									11,722,163		11,722,163
Research and Development Expense														$ 67,300,000		$ 67,300,000
ARES Trading License
Commitments and Contingencies Disclosure [Line Items]
Research and Development Expense														$ 1,600,000
Milestone payments, percentage														50.00%
Agreement commencement date														2015-05
Agreement termination, notice period														90 days
Deferred revenue, revenue recognized												1,600,000	1,600,000	$ 1,600,000	1,600,000
Deferred revenue, upfront payment												41,500,000	$ 47,900,000	41,500,000	$ 47,900,000					41,500,000			$ 57,500,000
MD Anderson License
Commitments and Contingencies Disclosure [Line Items]
Cash balance												$ 31,900,000		$ 31,900,000						$ 31,900,000
Series 1 Preferred Stock
Commitments and Contingencies Disclosure [Line Items]
Preferred stock, stated value \| $ / shares												$ 1,200	$ 1,200	$ 1,200	$ 1,200					$ 1,200
Development Milestone Payments \| ARES Trading License
Commitments and Contingencies Disclosure [Line Items]
Payments for development, regulatory and commercial milestones per Product														$ 60,000,000
Regulatory Milestone Payments \| ARES Trading License
Commitments and Contingencies Disclosure [Line Items]
Payments for development, regulatory and commercial milestones per Product														148,000,000
Commercial Milestone Payments \| ARES Trading License
Commitments and Contingencies Disclosure [Line Items]
Payments for development, regulatory and commercial milestones per Product														205,000,000
Substantive Milestones
Commitments and Contingencies Disclosure [Line Items]
Potential milestone payment												$ 15,000,000		15,000,000						$ 15,000,000
Subsequent Event
Commitments and Contingencies Disclosure [Line Items]
Research and Development Service Agreement Final Payments	$ 34,600,000
Subsequent Event \| MD Anderson License
Commitments and Contingencies Disclosure [Line Items]
Research and Development Service Agreement Final Payments		$ 2,700,000
Prepaid Expenses and Other Current Assets \| MD Anderson License
Commitments and Contingencies Disclosure [Line Items]
Cash balance												18,500,000		18,500,000						18,500,000
Other Noncurrent Assets \| MD Anderson License
Commitments and Contingencies Disclosure [Line Items]
Cash balance												13,400,000		$ 13,400,000						13,400,000
Intrexon Corporation/Precigen
Commitments and Contingencies Disclosure [Line Items]
Royalty percentage of net profit														20.00%
Percentage of revenue agreed to pay which is obtained from sublicensor														50.00%
Contract termination description														With respect to these "retained" Ziopharm Products, the Company's obligation to pay 20% of net profits derived from the sale of Ziopharm Products and 50% of revenue derived from a sublicensor will survive termination of the Channel Agreement.
Licensing fee				$ 10,000,000							$ 115,000,000
Milestone payment receivable														$ 5,000,000
Milestone payment receivable period														2 years
Upfront payment received											$ 57,500,000
Percentage of upfront fee Payable											50.00%
Milestone maximum payment												50,000,000		$ 50,000,000						50,000,000
Intrexon Corporation/Precigen \| 2016 GvHD Amendment
Commitments and Contingencies Disclosure [Line Items]
Licensing fee				$ 10,000,000
Research and Development Expense										$ 10,000,000
Intrexon Corporation/Precigen \| License Agreement
Commitments and Contingencies Disclosure [Line Items]
Cash consideration for license agreement					$ 50,000,000
Intrexon Corporation/Precigen \| Letter Agreement
Commitments and Contingencies Disclosure [Line Items]
Cash consideration for license agreement						$ 7,500,000
Intrexon Corporation/Precigen \| Quarterly Payment
Commitments and Contingencies Disclosure [Line Items]
Royalty percentage of net profit								20.00%
Percentage of revenue agreed to pay which is obtained from sublicensor								50.00%
Intrexon Corporation/Precigen \| Quarterly Payment \| 2016 GvHD Amendment \| After Amendment
Commitments and Contingencies Disclosure [Line Items]
Royalty percentage of net profit			20.00%
Intrexon Corporation/Precigen \| Quarterly Payment \| 2016 GvHD Amendment \| Before Amendment
Commitments and Contingencies Disclosure [Line Items]
Royalty percentage of net profit			50.00%
Intrexon Corporation/Precigen \| Quarterly Payment \| ECP Channel Agreement \| After Amendment
Commitments and Contingencies Disclosure [Line Items]
Royalty percentage of net profit			20.00%
Intrexon Corporation/Precigen \| Quarterly Payment \| ECP Channel Agreement \| Before Amendment
Commitments and Contingencies Disclosure [Line Items]
Royalty percentage of net profit			50.00%
Intrexon Corporation/Precigen \| Series 1 Preferred Stock
Commitments and Contingencies Disclosure [Line Items]
Issuance of common stock in licensing agreement, shares \| shares			100,000											13,460
Preferred stock, stated value \| $ / shares			$ 1,200
ZIOPHARM \| License Agreement
Commitments and Contingencies Disclosure [Line Items]
Common stock issued for cash \| shares					10,124,561
Cash consideration for license agreement					$ 50,000,000
ZIOPHARM \| Letter Agreement
Commitments and Contingencies Disclosure [Line Items]
Common stock issued for cash \| shares						1,597,602
Cash consideration for license agreement						$ 7,500,000
Minimum
Commitments and Contingencies Disclosure [Line Items]
Research and Development Expense					15,000,000
Maximum
Commitments and Contingencies Disclosure [Line Items]
Research and Development Expense					$ 20,000,000
New York, NY
Commitments and Contingencies Disclosure [Line Items]
Letter of credit												388,000		$ 388,000					$ 388,000	388,000
Operating lease expiration month and year																		2018-10
Loss on sublease																	$ 729,000
Remaining contractual obligation																	2,300,000
Sublease revenue from subtenant																	$ 1,600,000
Boston, MA
Commitments and Contingencies Disclosure [Line Items]
Operating lease expiration month and year																			2016-08
Security deposits												$ 128,000	$ 128,000	$ 128,000	$ 128,000					$ 128,000
Sublease term amendment														Aug. 31, 2021
Houston, TX \| Subsequent Event
Commitments and Contingencies Disclosure [Line Items]
Operating lease area \| ft²																					210
Operating Leases Future Minimum Monthly Payment Due Through Year 2021																					$ 1,000

Future Minimum Lease Payments under Operating Leases (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2018	$ 1,129
2019	723
2020	736
2021	489
2022 and beyond	0
Operating Leases, Future Minimum Payments Due, Total	3,077
Less: contractual sublease income	(278)
Future minimum lease payments, net	$ 2,799

Significant Component of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 89,098	$ 100,790
Start-up and organizational costs	37,488	59,360
Research and development credit carryforwards	32,395	34,845
Stock compensation	1,330	2,014
Capitalized acquisition costs	5,822	9,389
Deferred revenue	11,126	18,636
Depreciation	136	227
Other	993	1,537
Deferred Tax Assets Gross	178,388	226,798
Less valuation allowance	(178,388)	(226,798)
Effective tax rate	$ 0	$ 0

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Line Items]
Net operating loss carryforwards		$ 89,098	$ 100,790
Research and development credit carryforwards		$ 32,395	34,845
Net operating loss carryforwards, expiration date		2037
Accumulated excess tax benefit recognised as deferred tax asset		$ 0	$ 0
Increase (decrease) in deferred tax assets		$ (48,400)
Effective income tax rate		34.00%	34.00%	34.00%
ASU 2016-09
Income Taxes [Line Items]
Accumulated excess tax benefit recognised as deferred tax asset			$ 10,200
Accumulated Deficit \| ASU 2016-09
Income Taxes [Line Items]
Cumulative-effect adjustment from adoption of ASU 2016-09			$ 122
Tax Cuts And Jobs Act of 2017
Income Taxes [Line Items]
Effective income tax rate		35.00%
Change in tax rate in income tax expense benefit		$ 67,000
Tax Cuts And Jobs Act of 2017 \| Scenario, Forecast
Income Taxes [Line Items]
Effective income tax rate	21.00%
Research Tax Credit Carryforward
Income Taxes [Line Items]
Research and development credit carryforwards		35,000
Net Operating Loss Carryforwards
Income Taxes [Line Items]
Increase (decrease) in deferred tax assets					$ (11,200)
General Business Credits
Income Taxes [Line Items]
Increase (decrease) in deferred tax assets					$ (636)
Domestic Tax Authority
Income Taxes [Line Items]
Net operating loss carryforwards		$ 342,000
Net operating loss carryforwards, expiration date		2037
Federal and State
Income Taxes [Line Items]
Net operating loss carryforwards		$ 299,000

Reconciliation of Income Tax Expense (Benefit) (Detail)	12 Months Ended
Reconciliation of Income Tax Expense (Benefit) (Detail)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal income tax at statutory rates	34.00%	34.00%	34.00%
State income tax, net of federal tax benefit	4.00%	1.00%	5.00%
Research and development credits	3.00%	3.00%	3.00%
Stock compensation	(1.00%)	(1.00%)	(1.00%)
Channel rights	0.00%	(25.00%)	0.00%
Research and development true-up	(7.00%)	0.00%	0.00%
Officers compensation	(2.00%)	0.00%	0.00%
Other	(3.00%)	0.00%	0.00%
Federal rate change	(124.00%)	0.00%	0.00%
Increase in valuation allowance	96.00%	(12.00%)	(41.00%)
Effective tax rate	0.00%	0.00%	0.00%

Summary of Adjustments to Uncertain Tax Position (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Beginning Balance			$ 238
Increase/Decrease for tax positions related to the current year	$ 0	$ 0	0
Increase/Decrease for tax positions related to prior years	0	0	0
Decrease for settlements with applicable taxing authorities	0	0	0
Decrease for previous year's lapses of statute of limitations			(20)
Decrease for impact of §382 limitations			(218)
Decrease for lapses of statute of limitations	$ 0	$ 0	$ 0

Preferred Stock and Stockholders' Equity (Deficit) - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands							6 Months Ended	12 Months Ended
	May 11, 2017	Jun. 29, 2016	Feb. 17, 2015	Feb. 09, 2015	Feb. 03, 2015	Jan. 13, 2015	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jul. 01, 2016	Apr. 26, 2006
Equity [Line Items]
Shares of authorized capital stock												280,000,000
Common stock, shares authorized							250,000,000	250,000,000	250,000,000			250,000,000
Common stock par value per share							$ 0.001	$ 0.001	$ 0.001			$ 0.001
Preferred stock, shares authorized							30,000,000	30,000,000	30,000,000			30,000,000
Preferred stock par value							$ 0.001	$ 0.001	$ 0.001			$ 0.001
Stock issued during period	9,708,738
Issuance & sale of common stock in public offering price per share	$ 5.15
Sale of stock price per share	$ 4.893
Net proceeds from issuance of common stock	$ 47,300
Change in fair value of derivative liability							$ 124	$ 1,295	$ 124
Series 1 Preferred Stock
Equity [Line Items]
Preferred stock, stated value							$ 1,200	$ 1,200	$ 1,200
Maximum percentage of common stock issuable upon conversion of preferred stock								19.90%	19.90%
Fair value of Series 1 preferred stock as a component of temporary equity							$ 125,321	$ 143,992	$ 125,321
Temporary equity, fair value								18,900
Intrexon Corporation/Precigen
Equity [Line Items]
Stock issued during period					1,440,000
Embedded conversion liability								$ 900
Fair value of Series 1 preferred stock as a component of temporary equity											$ 118,200
Intrexon Corporation/Precigen \| Series 1 Preferred Stock
Equity [Line Items]
Issuance of common stock in licensing agreement (in shares)		100,000						13,460
Preferred stock, stated value		$ 1,200
Preferred stock, conversion rate								$ 1.00
Maximum percentage of common stock issuable upon conversion of preferred stock								19.90%
Preferred stock monthly dividend payable (per share)		$ 12.00
Intrexon Corporation/Precigen \| Series 1 Preferred Stock \| Before Conversion Event Date
Equity [Line Items]
Preferred stock monthly dividend payable (per share)								$ 12.00
Intrexon Corporation/Precigen \| Series 1 Preferred Stock \| Remaining Unconverted Shares
Equity [Line Items]
Preferred stock monthly dividend payable (per share)								$ 24.00
License Agreement
Equity [Line Items]
Issuance of common stock in licensing agreement (in shares)						11,722,163		11,722,163		11,722,163
J.P. Morgan Securities Inc.
Equity [Line Items]
Stock issued during period			1,500,000	10,000,000	10,000,000
Issuance & sale of common stock in public offering price per share					$ 8.75
Sale of stock price per share					$ 8.225
Option granted, exercisable period					30 days
Option to purchase common stock					1,500,000
Expected net proceeds from issuance of common stock			$ 94,300
Net proceeds from issuance of common stock			$ 94,300

Fair Value Assumptions Used in Probability Weighted Approach and Monte Carlo Simulation Model (Detail) - Series 1 Preferred Stock - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk-free interest rate	1.04%
Expected dividend rate	0.00%	0.00%
Expected volatility	70.50%
Preferred stock conversion limit-percentage of outstanding common stock	19.90%	19.90%
Preferred conversion floor price	$ 1.00	$ 1.00

Fair Values of Derivative Instruments to be classified as Derivative Liabilities on Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2016
Derivatives, Fair Value [Line Items]
Derivative liabilities	$ 2,424	$ 862	$ 694
Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	$ 2,424

Change in Derivative Liability (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Beginning Balance	$ 694	$ 862
Dividends	44	267
Change in fair value of derivative liabilities	124	1,295	$ 124
Ending Balance	$ 862	$ 2,424	$ 862

Fair Value Assumptions Used in Probability Weighted Approach and Monte Carlo Simulation Model for Derivatives (Detail) - Series 1 Preferred Stock - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk-free interest rate	1.04%
Expected dividend rate	0.00%	0.00%
Expected volatility	70.50%
Preferred stock conversion limit-percentage of outstanding common stock	19.90%	19.90%
Preferred conversion floor price	$ 1.00	$ 1.00
Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk-free interest rate	1.92%	1.04%
Expected volatility	68.70%	70.50%
Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk-free interest rate	2.12%	1.69%
Expected volatility	80.40%	72.70%

Stock Option Plan - Additional information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended											12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	May 31, 2017	Dec. 31, 2016	Jun. 30, 2016	May 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	May 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2012	Dec. 31, 2014	Jun. 18, 2014	May 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	526,364											526,364
Outstanding options issued	3,852,135				3,465,335			3,481,468				3,852,135	3,465,335	3,481,468		6,505,663
Proceeds from stock options exercised												$ 88	$ 714	$ 4,568
Total intrinsic value of options												$ 300	$ 1,500	$ 23,800
Stock options, granted												688,800	362,800	427,800
Stock options granted exercise price												$ 5.27	$ 6.40	$ 10.47
Stock options contractual life												6 years 5 months 20 days
Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period															3 years
Contractual terms															10 years
Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual terms															10 years
Director \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period															3 years
Director \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period															1 year
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repurchase of shares of restricted common stock	245,602		16,666	132,000	119,873	6,667	116,667	16,709	7,669
Repurchase of shares of restricted common stock, price per share	$ 4.14		$ 6.11	$ 7.12	$ 5.35	$ 7.74	$ 6.86	$ 8.31	$ 11.57
Restricted Stock \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years				3 years			3 years		3 years	3 years
Share-based payment award granted	838,000				625,750			403,083		50,000	1,000,000
Restricted Stock \| Non Employee Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year				1 year			1 year
Share-based payment award granted	69,032				86,020			133,305	4,186
Unvested Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs related to non-vested restricted stock outstanding	$ 5,100											$ 5,100
Expected recognition period												1 year 8 months 23 days
Unvested Restricted Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected recognition period												1 year 7 months 2 days
Share-based payment award granted												907,032	711,770	1,590,574
Unrecognized stock-based compensation expense related to non-vested restricted stock arrangements	$ 8,200											$ 8,200
the "2012 Plan"
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	9,000,000											9,000,000					5,000,000	4,000,000
the "2012 Plan" \| Employees \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options issued	3,214,635											3,214,635
the "2012 Plan" \| Director \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options issued	627,500											627,500
the "2012 Plan" \| Consultants \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options issued	10,000											10,000
Outside 2012 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options issued	500,000											500,000
Vesting period		3 years
Stock options, granted		500,000
Stock options granted exercise price		$ 6.16
Stock options contractual life		10 years
Share Based compensation arrangement by share based payment award options grants grant date fair value		$ 2,200

Stock Option Activity Under Stock Option Plan (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Shares
Beginning Balance	3,465,335	3,481,468	6,505,663
Granted	688,800	362,800	427,800
Exercised	(180,000)	(234,833)	(3,249,160)
Cancelled	(122,000)	(144,100)	(202,835)
Ending Balance	3,852,135	3,465,335	3,481,468
Options exercisable, at end of period	2,925,502	2,671,835
Weighted Average Exercise Price
Beginning Balance	$ 5.07	$ 4.96	$ 4.07
Granted	5.27	6.40	10.47
Exercised	3.67	4.57	3.95
Cancelled	6.64	6.43	4.36
Ending Balance	5.12	5.07	$ 4.96
Options exercisable, at end of period	$ 5.12	$ 4.40
Options available for future grant	303,928
Weighted Average Contractual Term (Years)
Outstanding, at end of period	6 years 5 months 20 days
Options exercisable, at end of period	5 years 6 months 29 days	5 years 10 months 17 days
Aggregate Intrinsic Value
Outstanding, at end of period	$ 1,152
Options exercisable, at end of period	$ 1,152	$ 3,383

Summary of Non-Vested Restricted Stock (Detail) - Unvested Restricted Common Stock - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Shares
Beginning Balance	1,680,492	1,586,388	144,508
Granted	907,032	711,770	1,590,574
Vested	(778,965)	(617,666)	(148,694)
Cancelled	0	0	0
Ending Balance	1,808,559	1,680,492	1,586,388
Weighted Average Grant Date Fair Value
Beginning Balance	$ 7.49	$ 9.00	$ 4.70
Granted	4.14	5.35	9.01
Vested	7.66	8.90	4.88
Cancelled	0	0	0
Ending Balance	$ 5.74	$ 7.49	$ 9.00

Employee Benefit Plan - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Benefits [Abstract]
Defined benefit plan contributions by employer	$ 90	$ 75	$ 47

Selected Quarterly Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 1,597	$ 1,598	$ 1,597	$ 1,597	$ 1,597	$ 1,598	$ 1,697	$ 1,969	$ 6,389	$ 6,861	$ 4,332
Total operating expenses	15,033	14,676	14,611	15,562	12,708	12,512	132,939	14,009	59,882	172,168	124,432
Loss from operations	(13,436)	(13,078)	(13,014)	(13,965)	(11,111)	(10,914)	(131,242)	(12,040)	(53,493)	(165,307)	(120,100)
Preferred stock dividends	(4,999)	(4,903)	(4,865)	(4,171)	(3,532)	(3,591)			(18,938)	(7,123)
Net (loss) applicable to common shareholders	$ (18,272)	$ (17,604)	$ (17,727)	$ (19,658)	$ (14,756)	$ (14,445)	$ (131,200)	$ (12,019)	$ (54,323)	$ (165,297)	$ (120,088)
Loss per share, basic and diluted	$ (0.12)	$ (0.13)	$ (0.13)	$ (0.15)	$ (0.11)	$ (0.11)	$ (1.01)	$ (0.09)	$ (0.53)	$ (1.32)	$ (0.96)