0000950170-21-001446 | 10-Q | XBRL Viewer

Print Document View Excel Document

Cover Page - shares	6 Months Ended
Cover Page - shares	Jun. 30, 2021	Jul. 31, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Document Quarterly Report	true
Document Transition Report	false
Entity Registrant Name	ZIOPHARM Oncology, Inc.
Entity Central Index Key	0001107421
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Trading Symbol	ZIOP
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		215,559,148
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-33038
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	84-1475642
Entity Address, Address Line One	One First Avenue
Entity Address, Address Line Two	Parris Building 34, Navy Yard Plaza
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02129
City Area Code	617
Local Phone Number	259-1970

BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 76,746	$ 115,069
Receivables	7,626	4,665
Prepaid expenses and other current assets	5,035	10,855
Total current assets	89,407	130,589
Property and equipment, net	11,606	10,231
Operating Lease, Right-of-Use Asset	5,371	4,650
Deposits	365	130
Other non-current assets	16	745
Total assets	106,765	146,345
Current liabilities:
Accounts payable	982	960
Accrued expenses	11,846	16,589
Lease liability - current portion	765	819
Total current liabilities	13,593	18,368
Lease liability - noncurrent portion	4,891	3,995
Total liabilities	18,484	22,363
Commitments and contingencies (Note 7)
Stockholders' equity:
Common stock, $0.001 par value; 350,000,000 shares authorized; 215,559,148 and 214,591,906 shares issued and outstanding at June 30, 2021 and December 31, 2020, respectively	216	215
Additional paid-in capital	896,390	887,868
Accumulated deficit	(808,325)	(764,101)
Total stockholders' equity	88,281	123,982
Total liabilities and stockholders' equity	$ 106,765	$ 146,345

BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	350,000,000	350,000,000
Common stock, shares issued	215,559,148	214,591,906
Common stock, shares outstanding	215,559,148	214,591,906

STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating expenses:
Research and development	$ 13,570	$ 12,051	$ 26,906	$ 24,757
General and administrative	9,069	6,555	17,296	12,509
Total operating expenses	22,639	18,606	44,202	37,266
Operating Income (Loss), Total	(22,639)	(18,606)	(44,202)	(37,266)
Other income (expense), net	(31)	10	(22)	377
Net loss	$ (22,670)	$ (18,596)	$ (44,224)	$ (36,889)
Basic and diluted net loss per share	$ (0.11)	$ (0.09)	$ (0.21)	$ (0.18)
Weighted average common shares outstanding used to compute basic and diluted net loss per share	214,426,406	212,792,403	214,191,839	206,303,586

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669619-108580

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721683-107760

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22595-107794

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669625-108580

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(18))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(20))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

Reference 13: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22663-107794

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121326447&loc=SL5780133-109256

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22658-107794

+ Details

STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($)	Total	Common Stock	Additional Paid In Capital	Accumulated Deficit
Balance at Dec. 31, 2019	$ 95,010,000	$ 182,000	$ 778,953,000	$ (684,125,000)
Balance (in shares) at Dec. 31, 2019		181,803,320
Stock-based compensation	3,601,000		3,601,000
Exercise of employee stock options	16,000		16,000
Exercise of employee stock options (in shares)		8,166
Issuance of restricted common stock	0	$ 1,000	(1,000)
Issuance of restricted common stock (in shares)		555,900
Issuance of common stock in connection with a public offering, net	88,661,000	$ 29,000	88,632,000
Issuance of common stock in connection with a public offering, net (in shares)		29,110,111
Issuance of common stock in connection with at the market offering, net	13,015,000	$ 2,000	13,013,000
Issuance of common stock in connection with at the market offering, net (in shares)		2,814,673
Net loss	(36,889,000)			(36,889,000)
Balance at Jun. 30, 2020	163,414,000	$ 214,000	884,214,000	(721,014,000)
Balance (in shares) at Jun. 30, 2020		214,292,170
Balance at Mar. 31, 2020	180,337,000	$ 214,000	882,541,000	(702,418,000)
Balance (in shares) at Mar. 31, 2020		214,286,337
Stock-based compensation	1,661,000		1,661,000
Exercise of employee stock options	12,000		12,000
Exercise of employee stock options (in shares)		5,833
Net loss	(18,596,000)			(18,596,000)
Balance at Jun. 30, 2020	163,414,000	$ 214,000	884,214,000	(721,014,000)
Balance (in shares) at Jun. 30, 2020		214,292,170
Balance at Dec. 31, 2020	123,982,000	$ 215,000	887,868,000	(764,101,000)
Balance (in shares) at Dec. 31, 2020		214,591,906
Stock-based compensation	7,486,000		7,486,000
Exercise of employee stock options	$ 1,036,000	$ 0	1,036,000
Exercise of employee stock options (in shares)	363,109	363,109
Restricted stock awards	$ 1,000	$ 1,000	0
Restricted stock awards (in shares)		726,224
Cancelled restricted common stock	0	$ 0
Cancelled restricted common stock (in shares)		122,091
Net loss	(44,224,000)			(44,224,000)
Balance at Jun. 30, 2021	88,281,000	$ 216,000	896,390,000	(808,325,000)
Balance (in shares) at Jun. 30, 2021		215,559,148
Balance at Mar. 31, 2021	105,641,000	$ 215,000	891,081,000	(785,655,000)
Balance (in shares) at Mar. 31, 2021		215,257,674
Stock-based compensation	5,290,000		5,290,000
Exercise of employee stock options	20,000		20,000
Exercise of employee stock options (in shares)		10,667
Restricted stock awards	0	$ 1,000	1,000
Restricted stock awards (in shares)		412,898
Cancelled restricted common stock (in shares)		122,091
Net loss	(22,670,000)			(22,670,000)
Balance at Jun. 30, 2021	$ 88,281,000	$ 216,000	$ 896,390,000	$ (808,325,000)
Balance (in shares) at Jun. 30, 2021		215,559,148

STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) $ in Millions	6 Months Ended
	Jun. 30, 2020 USD ($)
Market Offering [Member]
Issuance of common stock, commissions and expenses	$ 0.4
Public Offering [Member]
Issuance of common stock, commissions and expenses	$ 5.9

STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net loss	$ (44,224)	$ (36,889)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1,219	390
Stock-based compensation	7,486	3,601
(Increase) decrease in:
Receivables	(2,961)	(742)
Prepaid expenses and other current assets	5,820	6,838
Right of use asset	(721)	389
Other noncurrent assets	493	(634)
Increase (decrease) in:
Accounts payable	22	176
Accrued expenses	(4,742)	3,320
Lease liabilities	843	(361)
Net cash used in operating activities	(36,765)	(23,912)
Cash flows from investing activities:
Purchases of property and equipment	(2,594)	(4,000)
Net cash used in investing activities	(2,594)	(4,000)
Cash flows from financing activities:
Proceeds from exercise of stock options	1,036	16
Issuance of common stock in connection with a public offering, net	0	88,661
Issuance of common stock in connection with at the market offerings, net	0	13,015
Net cash provided by financing activities	1,036	101,692
Net increase in cash and cash equivalents, and restricted cash	(38,323)	73,780
Cash and cash equivalents, and restricted cash, beginning of period	115,069	79,741
Cash and cash equivalents, and restricted cash, end of period	76,746	153,521
Supplementary disclosure of cash flow information:
Accounts included in accrued expenses and accounts payable related to property and equipment	$ 258	$ 1,026

Business

6 Months Ended

Jun. 30, 2021

Accounting Policies [Abstract]

Business

1. Business

Overview

ZIOPHARM Oncology, Inc., which is referred to herein as “ZIOPHARM,” or the “Company,” 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 conducting research and development and raising capital to fund those efforts. In May 2021, the Company announced that it will be winding down our existing Controlled IL-12 clinical program for the treatment of recurrent glioblastoma multiforme. The Company will continue to seek a partner for this program and have also begun exploring potential synergies between this technology and our cell therapy programs. Costs incurred during the three and six months ended June 30, 2021 under the program wind down have been immaterial. The Company’s fiscal year ends on December 31.

The Company has operated at a loss since its inception in 2003 and has no recurring revenues from operations. The Company anticipates that losses will continue for the foreseeable future. As of June 30, 2021, the Company had approximately $76.7 million of cash and cash equivalents. The Company’s accumulated deficit at June 30, 2021 was approximately $808.3 million. Given its current development plans, the Company anticipates cash resources at June 30, 2021, plus the $25.0 million gross debt proceeds raised in August 2021, will be sufficient to fund operations into the fourth quarter of 2022. 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. 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 product candidates, management may need to curtail its development efforts and planned operations to conserve cash.

The Company’s amended and restated certificate of incorporation authorizes it to issue 350,000,000 shares of common stock. As of July 31, 2021, there were 215,559,148 shares of common stock outstanding and an additional 34,088,731 shares of common stock reserved for issuance pursuant to outstanding stock options and warrants.

Basis of Presentation

The accompanying unaudited interim financial statements have been prepared in accordance with the instructions to Form 10-Q pursuant to the rules and regulations of the Securities and Exchange Commission, or the SEC. Certain information and note disclosures required by generally accepted accounting principles in the United States have been condensed or omitted pursuant to such rules and regulations.

It is management’s opinion that the accompanying unaudited interim financial statements reflect all adjustments (which are normal and recurring) that are necessary for a fair statement of the results for the interim periods. The unaudited interim financial statements should be read in conjunction with the audited financial statements and the notes thereto for the year ended December 31, 2020, included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2020 filed with the SEC on March 1, 2021, or the Annual Report.

The year-end balance sheet data was derived from the audited financial statements but does not include all disclosures required by generally accepted accounting principles in the United States.

The results disclosed in the statements of operations for the three and six months ended June 30, 2021 are not necessarily indicative of the results to be expected for the full fiscal year 2021.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States 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 its financial statements are:



Clinical trial expenses and other research and development expenses;



Collaboration agreements;



Fair value measurements of stock-based compensation; and



Income taxes.

Impact of COVID-19 Pandemic

With the ongoing COVID-19 pandemic, the Company has implemented business continuity plans designed to address and mitigate the impact of the COVID-19 pandemic on its business and operations. The Company continues to evaluate the impact of the COVID-19 global pandemic on patients, healthcare providers and its employees, as well as its operations and the operations of its business partners and healthcare communities. In response to the COVID-19 pandemic, the Company has implemented policies at its locations to mitigate the risk of exposure to COVID-19 by its personnel, including restrictions on the number of staff in any given research and development laboratory and a work-from-home policy for non-laboratory functions, along with encouraging voluntary vaccination and voluntary sharing of vaccination data. The extent to which the COVID-19 pandemic impacts the Company’s business, clinical development and regulatory efforts and the value of its common stock, will depend on future developments that are highly uncertain and cannot be predicted with confidence at this time, such as the ultimate duration of the pandemic, travel restrictions, quarantines, social distancing and business closure requirements, and the effectiveness of actions taken globally to contain and treat the disease. The global economic slowdown, the overall disruption of global healthcare systems and the other risks and uncertainties associated with the COVID-19 pandemic could have a material adverse effect on the Company’s business, financial condition, results of operations and growth prospects.

Subsequent Events

The Company has evaluated subsequent events from the balance sheet date through the date on which these financial statements were issued. Except as disclosed below, the Company did not have any material subsequent events that impacted its financial statements or disclosures.

On August 6, 2021, the Company entered into a credit and security agreement with a lender (the “Term Loan Agreement”). The Term Loan Agreement provides for an initial term loan of $25.0 million funded at the closing, with an additional tranche of $25.0 million available if certain funding and clinical milestones are met by August 31, 2022. Interest on the term loan is payable monthly in arrears at an annual interest rate of the greater of 7.75% or the prime rate plus a margin of 4.5%. The term loan amortization date is April 1, 2022; provided, however, if the Company raises $50M in funding on or prior to March 31, 2022, the term loan first payment date shall automatically be extended to September 1, 2022. Further, if the Company raised $50M on or prior to March 31, 2022 and an additional $50M on or prior to August 31, 2022, the term loan amortization shall automatically be extended to September 1, 2023. The term loan maturity date is March 1, 2023; provided, however, if Company achieves the funding milestones, the term loan maturity date shall automatically be extended to August 1, 2025. There is a final payment due of 5.75%. The Company granted a warrant at the closing to purchase 432,843 shares at $2.22 per share. The Company will grant a similar warrant if it draws the second $25.0 million tranche.

Financings

6 Months Ended

Jun. 30, 2021

Text Block [Abstract]

Financings

2. Financings

February 2020 Public Offering

On February 5, 2020, the Company entered into an underwriting agreement with Jefferies, as representative of the several underwriters named therein, relating to the issuance and sale of 27,826,086 shares of its common stock. The price to the public in the offering was $3.25 per share, and the underwriters agreed to purchase the shares from the Company pursuant to the underwriting agreement at a purchase price of $3.055 per share.

The offering was made pursuant to the Company’s effective registration statement on Form S-3ASR (File No. 333-232283) previously filed with the SEC, and a prospectus supplement thereunder. The underwriters purchased the 27,826,086 shares on February 5, 2020. The net proceeds from the offering were approximately $84.8 million after deducting underwriting discounts and offering expenses paid by the Company.

On March 10, 2020, the underwriters exercised their option to purchase an additional 1,284,025 shares. The net proceeds were approximately $3.9 million after deducting underwriting discounts and offering expenses paid by the Company.

At-the-Market Facility

In June 2019, the Company entered into an Open Market Sale Agreement, or sales agreement, with Jefferies LLC, as agent, or Jefferies, pursuant to which the Company may offer and sell, from time to time through Jefferies, shares of its common stock having an aggregate offering price of up to $100.0 million. Shares will be sold pursuant to the Company’s effective registration statement on Form S-3ASR (File No. 333-232283), as previously filed with the SEC.

During the six months ended June 3, 2020, the Company sold an aggregate of 2,814,673 shares of its common stock at an average price of $4.77 per share under the ATM program. The net proceeds from sales under the ATM program were approximately $13.0 million after deducting underwriting discounts.

During the six months ended June 30, 2021, there were no sales under the Company’s ATM program.

Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2021

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

3. Summary of Significant Accounting Policies

The Company’s significant accounting policies were identified in the Company’s Annual Report. There have been no material changes in those policies since the filing of its Annual Report except as noted below.

New Accounting Pronouncements

In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which is intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in ASC 740 and also clarifies and amends existing guidance to improve consistent application. This guidance is effective for public entities for fiscal years beginning after December 15, 2020, and for interim periods within those fiscal years. The adoption did not have a material impact on the Company’s financial statements.

Fair Value Measurements

6 Months Ended

Jun. 30, 2021

Fair Value Disclosures [Abstract]

Fair Value Measurements

4. Fair Value Measurements

The Company accounts for its financial assets and liabilities using fair value measurements. The authoritative accounting guidance defines fair value, establishes a framework for measuring fair value under generally accepted accounting principles and enhances disclosures about fair value measurements. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy is based on three levels of inputs, of which the first two are considered observable and the last unobservable, that may be used to measure fair value as follows:



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 June 30, 2021 and December 31, 2020 were as follows:


($ in thousands)			Fair Value Measurements at Reporting Date Using
Description	Balance as of June 30, 2021		Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	$	71,809	$	71,809	$	—	$	—


($ in thousands)			Fair Value Measurements at Reporting Date Using
Description	Balance as of December 31, 2020		Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	$	75,990	$	75,990	$	—	$	—

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

Net Loss per Share

6 Months Ended

Jun. 30, 2021

Earnings Per Share [Abstract]

Net Loss per Share

5. Net Loss per Share

Basic net loss per share is computed by dividing net loss by the weighted average number of shares of common stock outstanding for the period. The Company’s potentially dilutive shares, which include outstanding common stock options, inducement stock options, unvested restricted stock and warrants, have not been included in the computation of diluted net loss per share for any of the periods presented as the result would be anti-dilutive. Such potentially dilutive shares of common stock consisted of the following as of June 30, 2021 and 2020, respectively:


	June 30,
	2021		2020
Stock options		10,186,829		6,561,513
Inducement stock options		463,333		863,333
Unvested restricted stock		1,065,175		1,354,306
Warrants		22,272,727		22,272,727
		33,988,064		31,051,879

Related Party Transactions

6 Months Ended

Jun. 30, 2021

Related Party Transactions

6. Related Party Transactions

Collaborations with Precigen/ PGEN

During the year ended December 31, 2018, the Company and PGEN Therapeutics, Inc. or PGEN, a wholly owned subsidiary of Precigen Inc., or Precigen, which was formerly known as Intrexon Corporation, entered into an Exclusive License Agreement (Note 7).

Collaboration with PGEN and MD Anderson

During the six months ended June 30, 2021 and 2020, the Company did not make any payments to MD Anderson. The total aggregate payments made in connection with this agreement have been $41.9 million since inception. The net balance of cash resources on hand at MD Anderson available to offset expenses and future costs is $1.8 million, which is included in prepaid expenses and other current assets. The classification is based on management’s current estimate of plans to utilize the prepaid balance and is subject to revision on a quarterly basis. At June 30, 2021 and December 31, 2020, the Company had accounts receivable due from MD Anderson of $7.6 million and $4.7 million, respectively.

Collaboration with Vineti Inc.

On July 9, 2020, the Company entered into a master service agreement and statement of work with Vineti, Inc., or Vineti. Pursuant to the agreements, Vineti is developing a software platform to coordinate and orchestrate the order, cell collection and manufacturing process for the Company’s TCR-T clinical programs. Heidi Hagen, who became a director of the Company in June 2019 and the Interim Chief Executive Officer on February 25, 2021, is a co-founder and former officer, of Vineti. During the three and six months ended June 30, 2021, the Company recorded expenses of approximately $0.1 million and $0.3 million for services performed by Vineti, respectively.

Joint Venture with TriArm Therapeutics/Eden Biocell

On December 18, 2018, the Company entered into a Framework Agreement with TriArm Therapeutics, Ltd., or TriArm, pursuant to which the parties agreed to launch Eden BioCell, Ltd., or Eden BioCell, to lead clinical development and commercialization of certain

Sleeping Beauty-generated CAR-T therapies as set forth in a separate license agreement. Eden BioCell is a joint venture in the People’s Republic of China (including Macau and Hong Kong), Taiwan and Korea. The Company licensed to Eden BioCell the rights in Greater China for its third-generation Sleeping Beauty-generated CAR-T therapies targeting the CD19 antigen. Eden BioCell is owned equally by the Company and TriArm and the parties share decision-making authority. TriArm has contributed $10.0 million to Eden BioCell. TriArm also manages all clinical development in the territory pursuant to a Master Services Agreement between TriArm and Eden BioCell. James Huang, who became a director of the Company in July 2020, Chairman of the Board of Directors in January 2021 and Executive Chairman in February 2021, was the founder and serves as managing partner of Panacea Venture, which is an investor in TriArm. Mr. Huang also serves as a member of Eden BioCell’s Board of Directors.

For the six months ended June 30, 2021 and 2020, Eden Biocell incurred a net loss and the Company continues to have no commitment to fund its operations.

Commitments and Contingencies

6 Months Ended

Jun. 30, 2021

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

7. Commitments and Contingencies

License Agreements

Exclusive License Agreement with PGEN Therapeutics

On October 5, 2018, the Company entered into an exclusive license agreement, or the License Agreement, with PGEN. As between the Company and PGEN, the terms of the License Agreement replace and supersede the terms of: (a) that certain Exclusive Channel Partner Agreement by and between the Company and Precigen, dated January 6, 2011, as amended by the First Amendment to Exclusive Channel Partner Agreement effective September 13, 2011, the Second Amendment to the Exclusive Channel Partner Agreement effective March 27, 2015, and the Third Amendment to Exclusive Channel Partner Agreement effective June 29, 2016, which was subsequently assigned by Precigen to PGEN; (b) certain rights and obligations pursuant to that certain License and Collaboration Agreement effective March 27, 2015 between ZIOPHARM, Precigen and ARES TRADING S.A., or Ares Trading, a subsidiary of Merck KGaA, or Merck, as assigned by Precigen to PGEN, or the Ares Trading Agreement; (c) that certain License Agreement between the Company, Precigen, and MD Anderson, with an effective date of January 13, 2015, or the MD Anderson License, which was subsequently assigned by Precigen and assumed by PGEN effective as of January 1, 2018; and (d) that certain Research and Development Agreement between the Company, Precigen and MD Anderson with an effective date of August 17, 2015, or the Research and Development Agreement, and any amendments or statements of work thereto.

Pursuant to the terms of the License Agreement, PGEN has granted the Company exclusive, worldwide rights to research, develop and commercialize (i) products utilizing PGEN’s RheoSwitch® gene switch, or RTS®, for the treatment of cancer, referred to as IL-12 Products, (ii) CAR products directed to (A) CD19 for the treatment of cancer, referred to as CD19 Products, and (B) a second target for the treatment of cancer, subject to the rights of Ares Trading to pursue such target under the Ares Trading Agreement, and (iii) T-cell receptor, or TCR, products designed for neoantigens for the treatment of cancer. PGEN has also granted the Company an exclusive, worldwide, royalty-bearing, sub-licensable license for certain patents relating to the Sleeping Beauty technology to research, develop and commercialize TCR products for both neoantigens and shared antigens for the treatment of cancer, referred to as TCR Products.

The Company is solely responsible for all aspects of the research, development and commercialization of the exclusively licensed products for the treatment of cancer. The Company is required to use commercially reasonable efforts to develop and commercialize IL-12 Products, CD19 Products and TCR Products.

In consideration of the licenses and other rights granted by PGEN, the Company pays PGEN an annual license fee of $0.1 million. The Company did not have any annual license expenses for the three and six months ended June 30, 2021 and 2020.

The Company will also make milestone payments totaling up to an additional $52.5 million for each exclusively licensed program upon the initiation of later stage clinical trials and upon the approval of exclusively licensed products in various jurisdictions. In addition, the Company will pay PGEN tiered royalties ranging from low-single digit to high-single digit on the net sales derived from the sales of any approved IL-12 Products and CAR Products. The Company will also pay PGEN royalties ranging from low-single digit to mid-single digit on the net sales derived from the sales of any approved TCR Products, up to a maximum royalty amount of $100.0 million in the aggregate. The Company will also pay PGEN 20% of any sublicensing income received by the Company relating to the licensed products.

PGEN will pay the Company royalties ranging from low-single digits to mid-single digits on the net sales derived from the sale of PGEN’s CAR products, up to $50.0 million.

During the three months ended June 30, 2021 and June 30, 2020 there were no expenses for services performed by PGEN. During the six months ended June 30, 2021 there were $0.1 million of expenses for services performed by PGEN and no expenses incurred

during the six months ended June 30, 2020. As of June 30, 2021, the Company did not have any outstanding liabilities related to services performed by PGEN. As of December 31, 2020, the Company had $0.1 million in accrued expenses related to services for amounts due to PGEN.

License Agreement—The University of Texas MD Anderson Cancer Center

On January 13, 2015, the Company, together with Precigen, entered into the MD Anderson License with MD Anderson (which Precigen subsequently assigned to PGEN). Pursuant to the MD Anderson License, the Company, together with Precigen, holds an exclusive, worldwide license to certain technologies owned and licensed by MD Anderson including technologies relating to novel 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 TCRs, arising from the laboratory of Laurence Cooper, M.D., Ph.D., who was the Company’s Chief Executive Officer from May 2015 to February 2021 and was formerly a tenured professor of pediatrics at MD Anderson. On February 25, 2021, the Company announced that Dr. Cooper was stepping down from his role as Chief Executive Officer and as a member of the Board of Directors, but will be remaining with the Company in a scientific advisory consulting role to support the Company's operations. Under the of a Separation Agreement, in exchange for a release of claims and certain post-employment covenants and in lieu of any severance benefits under his employment agreement, Dr. Cooper is entitled to receive continuing payments of his base salary and COBRA premiums for a period of 18 months, a cash payment $143,250, representing a pro-rata target amount of his annual performance bonus for 2021, a fully-vested restricted stock award with a grant value of $917,000, equivalent to the 2020 annual bonus Dr. Cooper would have been entitled to had his employment not terminated, and certain limited reimbursements for legal fees and housing. Dr. Cooper is not entitled to any equity acceleration in connection with his separation, however his equity awards are eligible to continue to vest pursuant to their terms based on his consulting services to the Company .Additionally, under Dr. Cooper's consulting agreement, he may earn consulting fees in amounts of up to $0.6 million for the first year and $0.3 million for each of the following two years and is also eligible for reimbursement of reasonable out-of-pocket business expenses.

The term of the MD Anderson License expires on the later 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 PGEN, shall 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 ZIOPHARM and PGEN 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 had 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 PGEN did not meet 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 PGEN, 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 the Company and PGEN and may be terminated by the mutual written agreement of the Company, PGEN, and MD Anderson.

On August 17, 2015, the Company, Precigen and MD Anderson entered into the Research and Development, or the 2015 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 2015 Agreement, the Company, Precigen and MD Anderson formed a joint steering committee to oversee and manage the new and ongoing research programs. Under the License Agreement with PGEN, the Company and PGEN agreed that PGEN would no longer participate on the joint steering committee after the date of the License Agreement. 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. On October 22, 2019, the Company entered into an amendment to the Research and Development Agreement extending its term until December 31, 2026.

During the three and six months ended June 30, 2021 and 2020, the Company made no payments to MD Anderson. The net balance of cash resources on hand at MD Anderson available to offset expenses and future costs is $1.8 million, which is included in prepaid expenses and other current assets on the Company’s balance sheet at June 30, 2021. There were also accounts receivable of $7.6 and $4.7 million due from MD Anderson at June 30, 2021 and December 31, 2020, respectively.

On October 22, 2019, the Company entered into the 2019 Research and Development Agreement, or the 2019 Agreement, with MD Anderson, pursuant to which the parties agreed to collaborate with respect to the Company’s Sleeping Beauty immunotherapy

program, which uses non-viral gene transfer to stably express and clinically evaluate neoantigen-specific TCRs in T cells. Under the 2019 Agreement, the parties will, among other things, collaborate on programs to expand the Company’s TCR library and conduct clinical trials.

The Company will own all intellectual property developed under the 2019 Agreement and will retain all rights to intellectual property for oncology products manufactured using non-viral gene transfer technologies under the Agreement, including the Company’s Sleeping Beauty technology. The Company has granted MD Anderson an exclusive license for such intellectual property outside the field of oncology and to develop and commercialize autologous TCR products manufactured using viral gene transfer technologies, and a non-exclusive license for allogeneic TCR products manufactured using viral-based technologies.

The Company has agreed, beginning on January 1, 2021, to reimburse MD Anderson up to a total of $20.0 million for development costs incurred starting after January 1, 2021 under the 2019 Agreement. In addition, the Company will pay MD Anderson royalties on net sales of its TCR products at rates in the low single digits. The Company is required to make performance-based payments upon the successful completion of clinical and regulatory benchmarks relating to its TCR products. The aggregate potential benchmark payments are $36.5 million, of which only $3.0 million will be due prior to the first marketing approval of the Company’s TCR products. The royalty rates and benchmark payments owed to MD Anderson may be reduced upon the occurrence of certain events. The Company also agreed that it will sell the Company’s TCR products to MD Anderson at preferential prices and will sell its TCR products in Texas exclusively to MD Anderson for a limited period of time following the first commercial sale of the Company’s TCR products. No costs have been incurred under this agreement as of June 30, 2021.

In connection with the execution of the 2019 Agreement, the Company issued MD Anderson a warrant to purchase 3,333,333 shares of common stock. Refer to Note 10 – Warrants for further details.

License Agreement with the National Cancer Institute

On May 28, 2019, the Company entered into a patent license agreement, or the Patent License, with the National Cancer Institute, or the NCI. Pursuant to the Patent License, the Company holds an exclusive, worldwide license to certain intellectual property to develop and commercialize patient-derived (autologous), peripheral blood T-cell therapy products engineered by transposon-mediated gene transfer to express TCRs reactive to mutated KRAS, TP53 and EGFR. In addition, pursuant to the Patent License, the Company holds an exclusive, worldwide license to certain intellectual property for manufacturing technologies to develop and commercialize autologous, peripheral blood T-cell therapy products engineered by non-viral gene transfer to express TCRs, as well as a non-exclusive, worldwide license to certain additional manufacturing technologies.

Pursuant to the terms of the Patent License, the Company is required to pay the NCI a cash payment in the aggregate amount of $1.5 million, payable in $0.5 million installments within sixty days, six-months, and the twelve-month anniversary of the effective date of the agreement of the Patent License. The $1.5 million was paid as of December 31, 2020.

On January 8, 2020, the Company entered into an amendment to the Patent License which expanded the TCR library to include additional TCRs reactive to mutated KRAS and TP53.

The terms of the Patent License also require the Company to pay the NCI minimum annual royalties in the amount of $0.3 million, which amount will be reduced to $0.1 million once the aggregate minimum annual royalties paid by the Company equals $1.5 million. The first minimum annual royalty payment is payable on the date that is eighteen months following the date of the Patent License. This payment was expensed during the first quarter of 2021.

On September 28, 2020, the Company entered into a second amendment to the patent license agreement which expanded the TCR library to include additional TCRs.

On April 16, the Company entered into a third amendment to the patent license agreement which modified the terms governing termination, modification and surrender of rights under the license.

On May 4, 2021, the Company entered into a fourth amendment to the patent license agreement which expanded the TCR library to include additional TCRs.

The Company is also required to make performance-based payments upon successful completion of clinical and regulatory benchmarks relating to the licensed products. The aggregate potential benchmark payments are $4.3 million, of which aggregate payments of $3.0 million are due only after marketing approval in the United States or in Europe, Japan, Australia, China or India. The first benchmark payment of $0.1 million will be due upon the initiation of the Company’s first sponsored Phase 1 clinical trial of a licensed product or licensed process in the field of use licensed under the Patent License, which has not been met at June 30, 2021.

In addition, the Company is required to pay the NCI one-time benchmark payments following aggregate net sales of licensed products at certain net sales up to $1.0 billion. The aggregate potential amount of these benchmark payments is $12.0 million. The Company must also pay the NCI royalties on net sales of products covered by the Patent License at rates in the low to mid-single digits depending upon the technology included in a licensed product. To the extent the Company enters into a sublicensing agreement relating to a licensed product, the Company is required to pay the NCI a percentage of all consideration received from a sublicensee, which percentage will decrease based on the stage of development of the licensed product at the time of the sublicense.

The Patent License will expire upon expiration of the last patent contained in the licensed patent rights, unless terminated earlier. The NCI may terminate or modify the Patent License in the event of a material breach, including if the Company does not meet certain milestones by certain dates, or upon certain insolvency events that remain uncured following the date that is 90 days following written notice of such breach or insolvency event. The Company may terminate the Patent License, or any portion thereof, in the Company’s sole discretion at any time upon 60 days’ written notice to the NCI. In addition, the NCI has the right to: (i) require the Company to sublicense the rights to the product candidates covered by the Patent License upon certain conditions, including if the Company is not reasonably satisfying required health and safety needs and (ii) terminate or modify the Patent License, including if the Company is not satisfying requirements for public use as specified by federal regulations.

During the three and six month periods ended June 30, 2021, the Company expensed $0.1 million and $0.3 million related to the patent services under this agreement. The Company did not incur expenses related to patent services during the three and six month periods ended June 30, 2020. Additionally, the Company recorded $0.3 million in accrued expenses as of June 30, 2021 related to patent services.

Cooperative Research and Development Agreement (CRADA) with the National Cancer Institute

On January 10, 2017, the Company announced the signing of a CRADA, with the NCI for the development of adoptive cell transfer, or ACT,-based immunotherapies genetically modified using the Sleeping Beauty transposon/transposase system to express TCRs for the treatment of solid tumors. The principal goal of the CRADA is to develop and evaluate ACT for patients with advanced cancers using autologous peripheral blood lymphocytes, or PBL, genetically modified using the non-viral Sleeping Beauty system to express TCRs that recognize neoantigens expressed within a patient’s cancer. Research conducted under the CRADA will be at the direction of Steven A. Rosenberg, M.D., Ph.D., Chief of the Surgery Branch at the NCI, in collaboration with the Company. In February 2019, the Company extended the CRADA with the NCI for two years, committing an additional $5.0 million to this program. The Company recorded $1.3 million of expense for both six-month periods ended June 30, 2021 and 2020 and $0.6 million of expenses for both three-month periods ended June 30, 2021 and 2020 respectively.

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, the Company was 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.

Under the terms of the agreement, the Company may be required to make additional payments to the Licensors 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. No amounts were accrued or paid during the three or six months ended June 30, 2021 and 2020.

Collaboration Agreement with Solasia Pharma K.K.

On March 7, 2011, the Company entered into a License and Collaboration Agreement with Solasia Pharma K.K., or Solasia, which was amended on July 31, 2014 to include an exclusive worldwide license. 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.

As consideration for the license, the Company is 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 the Company in

accordance with the terms of the license agreement with the Licensors. No amounts were received during the three or six months ended June 30, 2021 and 2020.

Collaboration with KBI

On July 9, 2020, the Company entered into a master service agreement and statement of work with KBI Biopharma, a contract manufacturing organization serving the biotechnology industry, including cell therapy. Pursuant to the agreements, KBI will provide cGMP cell therapy manufacturing and testing for the Company’s library TCR-T cell clinical program.

Collaboration with Aldevron

On March 3, 2019, the Company entered into a master services agreement with Aldevron, a plasmid DNA manufacturer. On June 25, 2020 Aldevron announced an agreement for Aldevron to produce DNA plasmids under their neoGMP® service to be utilized in the manufacture of the Company’s TCR-T cell therapies for treatment of solid tumors.

Leases

6 Months Ended

Jun. 30, 2021

Leases, Operating [Abstract]

Leases

8. Leases

In June 2012, the Company entered into a master lease for the Company’s corporate office headquarters in Boston, Massachusetts, which was originally set to expire in August 2016, but renewed through August 31, 2021. As of June 30, 2021 and December 31, 2020, a total security deposit of $0.1 million is included in deposits on the Company’s balance sheet.

On January 30, 2018, the Company entered into a lease agreement for office space in Houston, Texas, at MD Anderson. Under the terms of the Houston lease agreement, the Company leased approximately 210 square feet and were required to make rental payments at an average monthly rate of approximately $1 thousand. This lease was terminated effective March 31, 2020.

On January 30, 2018, the Company entered into a lease agreement, or the First Houston Lease, for office space in Houston, Texas at MD Anderson through April 2021. On March 12, 2019, the Company entered into a lease agreement, or the Second Houston Lease, for additional office space in Houston through April 2021. Under the terms of the First Houston Lease agreement, the Company leases approximately 1,038 square feet and is required to make rental payments at an average monthly rate of approximately $2 thousand through April 2021. Under the terms of the Second Houston Lease, the Company leases from MD Anderson, approximately 8,443 square feet and is initially required to make rental payments of approximately $17 thousand per month through February 2027, subject to an annual base rent increase of approximately 3.0% throughout the term. Effective April 13, 2020, the Company leased an additional 5,584 square feet from MD Anderson. The Company is initially required to make rental payments of approximately $12 thousand per month through February 2027, subject to an annual base rent increase of approximately 3.0% throughout the term. All future rent expense incurred in Houston, will be deducted from the Company’s prepayments to MD Anderson.

Effective December 15, 2020, the Company leased an additional 35,482 square feet from MD Anderson. The Company is initially required to make rental payments of approximately $37 thousand per month through April 2028, subject to an annual base rent increase of approximately 3.0% throughout the term beginning in April 2023. Future rent expense incurred in Houston, will be deducted from the Company’s prepayments to MD Anderson.

On April 22, 2021, the Company extended its lease for a 9,800 square foot portion of its corporate office headquarters in Boston. The renewal for its corporate office headquarters was originally set to expire on August 31, 2021, but has now been extended through August 2026. Under the terms of the renewal, the Company is required to make rental payments of approximately $26 thousand per month.

The components of lease expense were as follows:


	Three Months Ended June 30,						For the Six Months Ended June 30,
(in thousands)	2021			2020			2021			2020
Operating lease cost	$	380		$	236		$	761		$	471
Total lease cost	$	380		$	236		$	761		$	471
Weighted-average remaining lease term (years)		6.00		4.36				6.00		4.36
Weighted-average discount rate		8.00	%		8.00	%		8.00	%		8.00	%

Effective June 1, 2020, the Company entered into a noncancelable lease for a period of less than a year with monthly payments of approximately $10 thousand that is not subject to right of use asset recognition under ASC 842. Effective September 1, 2020, the Company added additional space to the noncancelable lease for a period of less than a year with monthly payments now totaling

approximately $15 thousand. Rent expense during the three and six months ended June 30, 2021 was $5 thousand. As of June 30, 2021, this lease has been terminated and the Company has no further obligation.

As of June 30, 2021, the maturities of the Company’s operating lease liabilities for the years ended December 31, were as follows (in thousands):


2021 (excluding the six months ended June 30, 2021)	$	617
2022		1,102
2023		1,132
2024		1,166
2025		1,201
Thereafter		1,873
Total lease payments		7,091
Less: Imputed interest and adjustments		(1,435	)
Present value of lease payments	$	5,656

Stock-Based Compensation

6 Months Ended

Jun. 30, 2021

Text Block [Abstract]

Stock-Based Compensation

9. Stock-Based Compensation

The Company recognized stock-based compensation expense on all employee and non-employee awards as follows:


	For the Three Months Ended June 30,				For the Six Months Ended June 30,
(in thousands)	2021		2020		2021		2020
Research and development		847		535		1,580		1,065
General and administrative		4,443		1,126		5,906		2,536
Stock-based compensation expense	$	5,290	$	1,661	$	7,486	$	3,601

The Company granted an aggregate of 41,500 and 4,395,438 stock options during the three and six months ended June 30, 2021 with a weighted-average grant date fair value of $2.27 and $2.44 per share, respectively. The Company granted an aggregate of 153,000 and 1,049,000 stock options during the three and six months ended June 30, 2020 with a weighted-average grant date fair value of $1.99 and $2.55 per share, respectively.

On March 4, 2021, the Company extended the contractual life of 216,700 fully vested stock options held by a former director of the Company. On April 5, 2021, the Company extended the contractual life of 751,371 stock options and accelerated the vesting of 226,889 shares of restricted stock held by a former officer of the Company. On April 29, 2021, the Company extended the contractual life of 10,417 vested and 167,023 unvested stock options and accelerated the vesting of 4,137 shares of restricted stock held by a former director. On May 17, 2021, the Company extended the contractual life of 347,267 vested stock options held by a former officer of the Company. These extensions resulted in additional stock compensation expense of approximately $1.9 million and $2.0 million during the three and six months ended June 30, 2021, respectively.

For the three months ended June 30, 2021 and 2020, the fair value of stock options was estimated on the date of grant using a Black-Scholes option valuation model with the following assumptions:


	For the Three Months Ended June 30,						For the Six Months Ended June 30,
	2021			2020			2021			2020
Risk-free interest rate		1.15	%	0.43 - 0.60%			0.09-1.15%			0.43 - 1.68%
Expected life in years	6.25			6-6.25			5.50 - 6.25			6 - 6.25
Expected volatility		74.08	%	73.10 - 73.90%			72.92 -74.80%			71.11 - 73.74%
Expected dividend yield		—	%		—	%		—	%		—	%

At June 30, 2021, there were 463,333 stock options that had been issued outside the 2012 Equity Incentive Plan, or the 2012 Plan and the 2020 Equity Incentive Plan, or the 2020 Plan. These options are excluded from the schedule below.

Stock option activity under the Company’s stock option plans for the three months ended June 30, 2021 is 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, 2020		6,840,719		$	3.81
Granted		4,395,438			3.79
Exercised		(363,109	)		2.86
Cancelled		(686,219	)		3.86
Outstanding, June 30, 2021		10,186,829		$	3.83		8.27	$	899
Options exercisable, June 30, 2021		4,970,314		$	4.13		7.23	$	771
Options exercisable, December 31, 2020		3,596,315		$	4.17		6.90	$	598
Options available for future grant		1,427,152

At June 30, 2021, total unrecognized compensation costs related to unvested stock options outstanding amounted to $11.3 million. The cost is expected to be recognized over a weighted-average period of 1.82 years.

A summary of the status of unvested restricted stock for the three months ended June 30, 2021 is as follows:


	Number of Shares			Weighted-Average Grant Date Fair Value
Unvested, December 31, 2020		786,280		$	3.08
Granted		726,224			3.75
Vested		(325,238	)		3.58
Cancelled		(122,091	)		3.61
Unvested, June 30, 2021		1,065,175		$	3.32

At June 30, 2021, total unrecognized compensation costs related to unvested restricted stock outstanding amounted to $2.2 million. The cost is expected to be recognized over a weighted-average period of 1.68 years.

At the Company’s annual meeting held on June 29, 2020, the shareholders approved the 2020 Equity Incentive Plan, or the 2020 Plan, which is a successor to and continuation of the 2012 Plan. The 2020 Plan had 21 million shares authorized, plus the shares remaining for issuance under the 2012 Plan. Our ability to utilize the total shares authorized under the 2020 Plan will be limited by the total number of shares authorized in our certificate of incorporation. As a result, as of June 30, 2021, there are 1,427,152 shares available to grant from the 2020 Plan. No additional awards can be granted from the 2012 Plan or the Company’s 2003 Stock Option Plan.

Warrants

6 Months Ended

Jun. 30, 2021

Warrants Disclosure [Abstract]

Warrant

10. Warrants

In connection with the Company’s November 2018 private placement which provided net proceeds of approximately $47.1 million, the Company issued warrants to purchase an aggregate of 18,939,394 shares of common stock, or the 2018 warrants, which became exercisable six months after the closing of the private placement. The warrants have an exercise price of $3.01 per share and have a five-year term. The relative fair value of the warrants was estimated at $18.4 million using a Black-Scholes model with the following assumptions: expected volatility of 71%, risk free interest rate of 2.99%, expected life of five years and no dividends.

The Company assessed whether the warrants require accounting as derivatives. The Company determined that the warrants were (1) indexed to the Company’s own stock and (2) classified in stockholders’ equity in accordance with Financial Accounting Standards Board, or (FASB) Accounting Standards Codification (“ASC”) Topic 815, Derivatives and Hedging. As such, the Company has concluded the warrants meet the scope exception for determining whether the instruments require accounting as derivatives and should be classified in stockholders’ equity.

On July 26, 2019 and September 12, 2019, the Company entered into agreements with existing investors for the exercise of previously issued warrants to purchase common stock in the private placement. Pursuant to the terms of the agreements, investors exercised their 2018 warrants for an aggregate of 17,803,031 shares of common stock, at an exercise price of $3.01 per share. Proceeds from the warrant exercise, after deducting placement agent fees and other related expenses of $1.1 million were approximately $52.5 million. The Company issued participating investors new warrants to purchase up to 17,803,031 additional shares of common stock, or the 2019 warrants, as an inducement for the warrant holders to exercise their 2018 warrants. The 2019 warrants will expire on the fifth

anniversary of the initial exercise date and have an exercise price of $7.00. The 2019 warrants were valued using a Black-Scholes valuation model and resulted in a $60.8 million non-cash charge to the Company’s statement of operations in 2019.

On October 22, 2019, the Company entered into the 2019 Agreement with MD Anderson. Refer to Note 7 – Commitments and Contingencies for further details. In connection with the execution of the 2019 Agreement, the Company issued MD Anderson a warrant to purchase 3,333,333 shares of common stock. The warrant has an initial exercise price of $0.001 per share and grant date fair value of $14.5 million. The warrant expires on December 31, 2026 and vests upon the occurrence of certain clinical milestones. The Company will recognize expense on the warrant in the same manner as if the Company paid cash for services to be rendered. The Company has not recognized any expense related to the warrant as of June 30, 2021, as no work towards any of the specified clinical milestones has begun.

Joint Venture

6 Months Ended

Jun. 30, 2021

Equity Method Investments and Joint Ventures [Abstract]

Joint Venture

11. Joint Venture

On December 18, 2018, the Company entered into a Framework Agreement with TriArm pursuant to which the parties agreed to launch Eden BioCell, to lead clinical development and commercialization of certain Sleeping Beauty-generated CAR-T therapies as set forth in a separate license agreement (see Note 6).

On January 3, 2019, Eden BioCell was incorporated in Hong Kong as a private company. Eden BioCell, the Company and TriArm entered into a Share Subscription Agreement on January 23, 2019, where the Company and TriArm agreed to contribute certain intellectual property, services and cash (only with respect to TriArm) to Eden BioCell to subscribe for a certain number of newly issued ordinary shares in the share capital of Eden BioCell. On the closing date, upon the issuance and subscription of the shares, in respect of the aforementioned consideration, 10,000,000 ordinary shares were issued to the Company and 10,000,000 ordinary shares were issued to TriArm.

The closing of the transaction occurred on July 5, 2019. The Framework Agreement and Share Subscription Agreements were each respectively amended to be effective as of this date. Upon consummation of the joint venture, Eden BioCell and the Company also entered into a license agreement, pursuant to which the Company licensed the rights to Eden BioCell for third-generation Sleeping Beauty-generated CAR-T therapies targeting the CD19 antigen for the territory of China (including Macau and Hong Kong), Taiwan and Korea. Eden BioCell will be responsible for certain milestone and royalty payments related to the Company’s license agreements with MD Anderson and PGEN (see Note 7). TriArm entered into a master services agreement with Eden BioCell and contributed $10.0 million of cash on the closing date. TriArm and the Company each received a 50% equity interest in the joint venture in exchange for their contributions to Eden BioCell.

As of July 5, 2019, as a result of the design and purpose of Eden BioCell, the Company determined that Eden BioCell was considered a variable interest entity, or VIE, and concluded that it is not the primary beneficiary of the VIE as it did not have the power to direct the activities of the VIE that most significantly impact its performance. Rather, the Company accounts for the equity interest in Eden BioCell under the equity method of accounting as it has the ability to exercise significant influence over the operations of Eden BioCell.

The Company determined that Eden BioCell was not a customer and therefore, accounted for the transaction as the transfer of nonfinancial assets to be recognized at their fair value on the contribution date. The fair value of the intellectual property contributed to Eden BioCell had a de minimis value due to the early stage of the technology and the likelihood of clinical success. Due to the de minimis fair value of the intellectual property contributed, the Company did not record a gain or loss on this transaction and recognized no value for its equity-method investment.

In March 2021 and as announced by the Company in April 2021, Eden BioCell, the Company’s Joint Venture in Taiwan with Tri-Arm Therapeutics, began treating patients in a clinical trial with the Company’s investigational CD19 RPM CAR-T cell therapy, under the IND cleared by the Taiwan FDA in December. Two patients have now been treated in this trial. The lead investigator at National Taiwan University in Taipei, has reported no serious adverse safety events in either of these patients. Laboratory results continue to support, as previously published, that non-viral Sleeping Beauty gene transfer is effective in genetically modifying autologous T-cells. Patients were infused two days after gene transfer, thus shortening the turnaround time and demonstrating an advantage over viral methods.

Based on laboratory data from the first two patients generated between March and May 2021, the Tri-Arm/Eden team concluded, in concert with the investigator and the team at Ziopharm, that further process development work is required. This additional work will optimize and refine the manufacturing process in order to more consistently manufacture product in the desired clinical dose range seeking to be studied.

The Tri-Arm/Eden team, per the terms of the JV agreement, will undertake the necessary process development work before infusing additional patients. This will take an unspecified amount of time. Additionally, the ongoing COVID outbreak in Taiwan presents additional uncertainty to the timeline, as the operational activities in the manufacturing suite are currently slowed due to employee restrictions related to the pandemic. These restrictions are impacting clinical trials broadly in Taiwan.

For the three and six months ended June 30, 2021 and 2020, Eden BioCell incurred a net loss and the Company continues to have no commitment to fund its operations.

Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2021
Accounting Policies [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which is intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in ASC 740 and also clarifies and amends existing guidance to improve consistent application. This guidance is effective for public entities for fiscal years beginning after December 15, 2020, and for interim periods within those fiscal years. The adoption did not have a material impact on the Company’s financial statements.

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2021

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured at Fair Value on Recurring Basis

Assets and liabilities, measured at fair value on a recurring basis as of June 30, 2021 and December 31, 2020 were as follows:


($ in thousands)			Fair Value Measurements at Reporting Date Using
Description	Balance as of June 30, 2021		Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	$	71,809	$	71,809	$	—	$	—


($ in thousands)			Fair Value Measurements at Reporting Date Using
Description	Balance as of December 31, 2020		Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	$	75,990	$	75,990	$	—	$	—

Net Loss per Share (Tables)

6 Months Ended

Jun. 30, 2021

Earnings Per Share [Abstract]

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

The Company’s potentially dilutive shares, which include outstanding common stock options, inducement stock options, unvested restricted stock and warrants, have not been included in the computation of diluted net loss per share for any of the periods presented as the result would be anti-dilutive. Such potentially dilutive shares of common stock consisted of the following as of June 30, 2021 and 2020, respectively:


	June 30,
	2021		2020
Stock options		10,186,829		6,561,513
Inducement stock options		463,333		863,333
Unvested restricted stock		1,065,175		1,354,306
Warrants		22,272,727		22,272,727
		33,988,064		31,051,879

Leases (Tables)

6 Months Ended

Jun. 30, 2021

Leases, Operating [Abstract]

Components of Lease Expense

The components of lease expense were as follows:


	Three Months Ended June 30,						For the Six Months Ended June 30,
(in thousands)	2021			2020			2021			2020
Operating lease cost	$	380		$	236		$	761		$	471
Total lease cost	$	380		$	236		$	761		$	471
Weighted-average remaining lease term (years)		6.00		4.36				6.00		4.36
Weighted-average discount rate		8.00	%		8.00	%		8.00	%		8.00	%

Lessee, Operating Lease, Liability, Maturity

As of June 30, 2021, the maturities of the Company’s operating lease liabilities for the years ended December 31, were as follows (in thousands):


2021 (excluding the six months ended June 30, 2021)	$	617
2022		1,102
2023		1,132
2024		1,166
2025		1,201
Thereafter		1,873
Total lease payments		7,091
Less: Imputed interest and adjustments		(1,435	)
Present value of lease payments	$	5,656

Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2021

Text Block [Abstract]

Stock-Based Compensation Expense on All Employee and Non-Employee Awards

The Company recognized stock-based compensation expense on all employee and non-employee awards as follows:


	For the Three Months Ended June 30,				For the Six Months Ended June 30,
(in thousands)	2021		2020		2021		2020
Research and development		847		535		1,580		1,065
General and administrative		4,443		1,126		5,906		2,536
Stock-based compensation expense	$	5,290	$	1,661	$	7,486	$	3,601

Fair Value of Stock Options Assumptions Using Black-Scholes Option Valuation Model

For the three months ended June 30, 2021 and 2020, the fair value of stock options was estimated on the date of grant using a Black-Scholes option valuation model with the following assumptions:


	For the Three Months Ended June 30,						For the Six Months Ended June 30,
	2021			2020			2021			2020
Risk-free interest rate		1.15	%	0.43 - 0.60%			0.09-1.15%			0.43 - 1.68%
Expected life in years	6.25			6-6.25			5.50 - 6.25			6 - 6.25
Expected volatility		74.08	%	73.10 - 73.90%			72.92 -74.80%			71.11 - 73.74%
Expected dividend yield		—	%		—	%		—	%		—	%

Stock Option Activity under Stock Option Plan

Stock option activity under the Company’s stock option plans for the three months ended June 30, 2021 is 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, 2020		6,840,719		$	3.81
Granted		4,395,438			3.79
Exercised		(363,109	)		2.86
Cancelled		(686,219	)		3.86
Outstanding, June 30, 2021		10,186,829		$	3.83		8.27	$	899
Options exercisable, June 30, 2021		4,970,314		$	4.13		7.23	$	771
Options exercisable, December 31, 2020		3,596,315		$	4.17		6.90	$	598
Options available for future grant		1,427,152

Summary of Unvested Restricted Stock

A summary of the status of unvested restricted stock for the three months ended June 30, 2021 is as follows:


	Number of Shares			Weighted-Average Grant Date Fair Value
Unvested, December 31, 2020		786,280		$	3.08
Granted		726,224			3.75
Vested		(325,238	)		3.58
Cancelled		(122,091	)		3.61
Unvested, June 30, 2021		1,065,175		$	3.32

Business - Additional Information (Detail) - USD ($)	1 Months Ended		6 Months Ended
Business - Additional Information (Detail) - USD ($)	Aug. 31, 2021	Aug. 06, 2021	Jun. 30, 2021	Jul. 31, 2021	Dec. 31, 2020
Cash and cash equivalents			$ 76,746,000		$ 115,069,000
Accumulated deficit			$ 808,325,000		$ 764,101,000
Common Stock, Shares Authorized			350,000,000		350,000,000
Common Stock, Shares, Outstanding			215,559,148		214,591,906
Description of payment terms			The term loan amortization date is April 1, 2022; provided, however, if the Company raises $50M in funding on or prior to March 31, 2022, the term loan first payment date shall automatically be extended to September 1, 2022. Further, if the Company raised $50M on or prior to March 31, 2022 and an additional $50M on or prior to August 31, 2022, the term loan amortization shall automatically be extended to September 1, 2023. The term loan maturity date is March 1, 2023; provided, however, if Company achieves the funding milestones, the term loan maturity date shall automatically be extended to August 1, 2025. There is a final payment due of 5.75%.
Common Stock [Member]
Common Stock, Shares Authorized			50,000,000
Common Stock, Shares, Outstanding				215,559,148
Common stock reserved for future issuance				34,088,731
Forecast [Member]
Gross proceeds from debt	$ 25,000,000.0
Forecast [Member] \| Warrants [Member]
Warrant exercise per share		$ 2.22
Warrants granted to purchase shares of closing		432,843
Warrant granted to draw tranche		$ 25,000.0
Forecast [Member] \| Term Loan [Member]
Initial term loan		25,000,000.0
Additonal tranche facility		$ 25,000,000.0
Debt Instrument, maturity date		Mar. 01, 2023
Term loan maturity date, extended		Aug. 01, 2025
Term loan, amortization date		Apr. 01, 2022
Term loan amortization date, extended		Sep. 01, 2023
Percentage of final payment due		5.75%
Raise fund		$ 50,000
Forecast [Member] \| Term Loan [Member] \| Prime Rate [Member]
Interest rate		4.50%
Forecast [Member] \| Term Loan [Member] \| Maximum [Member]
Interest rate		7.75%

Financings - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			6 Months Ended
	Mar. 10, 2020	Feb. 05, 2020	Jun. 30, 2021	Jun. 30, 2020
Class of Stock [Line Items]
Sale of stock consideration received on transaction			$ 0	$ 88,661
At The Market Offering [Member]
Class of Stock [Line Items]
Stock issued during period			0	2,814,673
Sale of stock consideration received on transaction				$ 13,000
par value per share				$ 4.77
Underwriting Agreement [Member]
Class of Stock [Line Items]
Stock issued during period		27,826,086
Issuance & sale of common stock in public offering price per share		$ 3.25
Sale of stock consideration received on transaction		$ 84,800
par value per share		$ 3.055
Underwriting Agreement [Member] \| Stock Option [Member]
Class of Stock [Line Items]
Stock issued during period	1,284,025
Sale of stock consideration received on transaction	$ 3,900

Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 71,809	$ 75,990
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	$ 71,809	$ 75,990

Potential Dilutive Shares Excluded from Computation of Diluted Net Loss Per Share (Detail) - shares	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	33,988,064	31,051,879
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	22,272,727	22,272,727
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	10,186,829	6,561,513
Stock Options \| Two Thousand Twelve Stock Option Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	463,333	863,333
Unvested Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	1,065,175	1,354,306

Related Party Transactions - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2015	Dec. 31, 2020
Related Party Transaction [Line Items]
Research and development expense	$ 13,570	$ 12,051	$ 26,906	$ 24,757
M.D. Anderson Cancer Center
Related Party Transaction [Line Items]
Due from Related Parties, Current	7,600		7,600			$ 4,700
MD Anderson License and the Research and Development Agreement [Member]
Related Party Transaction [Line Items]
Cash resources on hand	1,800		1,800
License Agreement \| M.D. Anderson Cancer Center
Related Party Transaction [Line Items]
Issuance of common stock in licensing agreement (in shares)					11,722,163
Research and development expense					$ 67,300
Cooperative Research and Development Agreement \| M.D. Anderson Cancer Center
Related Party Transaction [Line Items]
Research and development service agreement aggregate payments			41,900
Vineti Inc [Member] \| Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Related Party Transaction Expenses From Transactions With Related Party Advisory Fees	$ 100		300
Eden Biocell [Member]
Related Party Transaction [Line Items]
Payments to Fund Long-term Loans to Related Parties			$ 10,000

Commitments and Contingencies - Additional Information (Detail) - USD ($)			3 Months Ended		6 Months Ended		12 Months Ended
	May 28, 2019	Jan. 13, 2015	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2017	Nov. 28, 2020	Oct. 22, 2019	Feb. 19, 2019	May 10, 2018	Aug. 24, 2004
Accrued Payments
Research and development expense			$ 13,570,000	$ 12,051,000	$ 26,906,000	$ 24,757,000
Cash balance			76,746,000		76,746,000		$ 115,069,000
Agreement commencement date								2015-05
Expected Cash Payment Payable									$ 1,500,000
Minimum Royalties Amount Payable									$ 100,000
Annual Licensing fee paid			0
Receivables			7,626,000		7,626,000		4,665,000
Restricted stock awards			$ 0		$ 1,000
MD Anderson Warrant [Member]
Accrued Payments
Number of Warrants			3,333,333		3,333,333
MD Anderson License and the Research and Development Agreement [Member]
Accrued Payments
Research and development service agreement aggregate quarterly payments					$ 15,000,000.0
Reimbursement of historical costs										$ 20,000,000.0
Aggregate potential benchmark payments										36,500,000
Accrued Payments										$ 3,000,000.0
Development costs incurred					0
CRADA Agreement [Member]
Accrued Payments
Obligations due under contract											$ 5,000,000.0
Quarterly payments under contract					1,300,000	1,300,000
CAR Products [Member]
Accrued Payments
Amount of royalties receivable												$ 50,000,000.0
The University of Texas MD Anderson Cancer Center and The Texas A & M University System
Accrued Payments
Milestone maximum payment													$ 4,500,000
Cash payment			$ 143,250		143,250
Restricted stock awards					917,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Two			300,000		300,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Three			300,000		300,000
MD Anderson License
Accrued Payments
Receivables			7,600,000		7,600,000		4,700,000
License Agreement with the National Cancer Institute [Member]
Accrued Payments
Minimum Royalties Amount Payable			300,000		300,000
Ziop License Agreement With The National Cancer Institute [Member]
Accrued Payments
Expected Cash Payment Payable	$ 1,500,000
Expected cash payment payable per installments	500,000
Minimum Royalties Amount Payable	$ 300,000
Description Of First Annual Royalty Payable	The first minimum annual royalty payment is payable on the date that is eighteen months following the date of the Patent License
Description Of First Benchmark Payable	The first benchmark payment of $0.1 million will be due upon the initiation of the Company’s first sponsored Phase 1 clinical trial of a licensed product or licensed process in the field of use licensed under the Patent License, which has not been met at June 30, 2021.
Description Of option To terminate Agreement	The NCI may terminate or modify the Patent License in the event of a material breach, including if the Company does not meet certain milestones by certain dates, or upon certain insolvency events that remain uncured following the date that is 90 days following written notice of such breach or insolvency event
Agreement termination, notice period	60 days
payments under the Patent License							1,500,000
Annual Licensing fee paid				0	0	0
Ziop License Agreement With The National Cancer Institute [Member] \| Performance Based Payments Member [Member]
Accrued Payments
Aggregate Benchmark Payments Payable	$ 4,300,000
Ziop License Agreement With The National Cancer Institute [Member] \| One Time Benchmark Payments [Member]
Accrued Payments
Potential Benchmark Payments Payable	12,000,000.0
Ziop License Agreement With The National Cancer Institute [Member] \| Post Marketing Approval [Member] \| Performance Based Payments Member [Member]
Accrued Payments
Aggregate Benchmark Payments Payable	3,000,000.0
Ziop License Agreement With The National Cancer Institute [Member] \| licensed products [Member] \| One Time Benchmark Payments [Member]
Accrued Payments
Maximum Sales Revenue On Which Benchmark Payments Payable	$ 1,000,000,000.0
Patent And Technology License Agreement [Member] \| The University of Texas MD Anderson Cancer Center and The Texas A & M University System
Accrued Payments
Accrued payments			0	0	0	0
Collaboration Agreement With Solasia Pharma KK [Member]
Accrued Payments
Accrued payments or receipts			0	0	0	0
License Agreement With PGEN Therapeutics [Member] \| License [Member]
Accrued Payments
Cost of Goods and Services Sold			0	0	100,000	$ 0
Prepaid Expenses and Other Current Assets \| MD Anderson License
Accrued Payments
Cash balance			1,800,000		1,800,000
Intrexon Corporation
Accrued Payments
Annual License Fees												100,000
Expected additional milestones payable												52,500,000
Expected Cash Payment Payable			100		100		$ 100
Intrexon Corporation \| T-cell receptor
Accrued Payments
Maximum royalty amount												$ 100,000,000.0
Portion of income payable to related party												20.00%
Minimum \| License Agreement with the National Cancer Institute [Member]
Accrued Payments
Royalty fee			100
Minimum \| Ziop License Agreement With The National Cancer Institute [Member]
Accrued Payments
Royalty fee				$ 300,000
Maximum [Member] \| MD Anderson License and the Research and Development Agreement [Member]
Accrued Payments
Research and development expense		$ 20,000,000.0
Maximum [Member] \| The University of Texas MD Anderson Cancer Center and The Texas A & M University System
Accrued Payments
Defined Benefit Plan, Expected Future Benefit Payment, Year One			$ 600,000		$ 600,000

Leases - Components of Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating lease cost	$ 380	$ 236	$ 761	$ 471
Total lease cost	$ 380	$ 236	$ 761	$ 471
Operating Lease, Weighted Average Remaining Lease Term	6 years	4 years 4 months 9 days	6 years	4 years 4 months 9 days
Weighted-average discount rate	8.00%	8.00%	8.00%	8.00%

Leases - Operating Lease Liabilities (Detail) $ in Thousands	Jun. 30, 2021 USD ($)
2021 (excluding the six months ended June 30, 2021)	$ 617
2022	1,102
2023	1,132
2024	1,166
2025	1,201
Thereafter	1,873
Total lease payments	7,091
Less: Imputed interest and adjustments	(1,435)
Present value of lease payments	$ 5,656

Leases - Additional Information (Details) $ in Thousands							3 Months Ended	6 Months Ended
Leases - Additional Information (Details) $ in Thousands	Apr. 22, 2021 USD ($)	Dec. 15, 2020 USD ($) ft²	Jun. 01, 2020 USD ($)	Apr. 13, 2020 USD ($) ft²	Oct. 15, 2019 USD ($) ft²	Mar. 12, 2019 USD ($) ft²	Jun. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Apr. 30, 2021 ft²	Dec. 31, 2020 USD ($)	Jan. 30, 2018 USD ($) ft²
Land Subject to Ground Leases \| ft²						1,038			9,800
Operating Lease Monthly Rental Payment			$ 10			$ 2
Operating lease rental expenses							$ 5	$ 5
Lease obligation							5,656	5,656
Boston, MA
Security Deposit							100	$ 100		$ 100
Sublease term amendment								Aug. 31, 2021
Operating lease expiration month and year								2016-08
Lessee Operating Lease Monthly Rental Payment	$ 26
Houston, TX
Land Subject to Ground Leases \| ft²		35,482			8,443
Operating Lease Area \| ft²				5,584							210
Operating Leases Future Minimum Monthly Payment Due Through Year 2021		$ 37		$ 12	$ 17						$ 1
Annual Base Rent		3.00%		3.00%	3.00%
Lessee Operating Lease Monthly Rental Payment			$ 15
Lease obligation							$ 0	$ 0

Stock-Based Compensation Expense Included in Statement of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 5,290	$ 1,661	$ 7,486	$ 3,601
Research and Development Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	847	535	1,580	1,065
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 4,443	$ 1,126	$ 5,906	$ 2,536

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions				3 Months Ended		6 Months Ended
	Apr. 29, 2021	Apr. 05, 2021	Mar. 04, 2021	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	May 17, 2021	Dec. 31, 2020	Jun. 29, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options issued		751,371		10,186,829		10,186,829		347,267	6,840,719
Stock options, granted				41,500	153,000	4,395,438	1,049,000
Options available for future grant				1,427,152		1,427,152
Weighted-average grant date fair value				$ 2.27	$ 1.99	$ 2.44	$ 2.55
Number of options vested	10,417		216,700
Adiitional stock compensation expenses				$ 1.9		$ 2.0
Unvested Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs related to unvested restricted stock outstanding				11.3		$ 11.3
Expected recognition period						1 year 9 months 25 days
Number of Unvested Stock options	167,023
Unvested Restricted Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs related to unvested restricted stock outstanding				$ 2.2		$ 2.2
Expected recognition period						1 year 8 months 4 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Accelerated Vesting Share	4,137	226,889
Outside 2012 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options issued				463,333		463,333
2020 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options available for future grant				1,427,152		1,427,152
Shares available for new issue										21,000,000
2012 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options available for future grant				0		0
2003 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options available for future grant				0		0

Fair Value of Stock Options Assumptions Using Black-Scholes Option Valuation Model (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Risk-free interest rate	1.15%
Risk-free interest rate, Minimum		0.43%	0.09%	0.43%
Risk-free interest rate, Maximum		0.60%	1.15%	1.68%
Expected life in years	6 years 3 months
Expected volatility	74.08%
Expected volatility, Minimum		73.10%	72.92%	71.11%
Expected volatility, Maximum		73.90%	74.80%	73.74%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Maximum [Member]
Expected life in years		6 years 3 months	6 years 3 months	6 years 3 months
Minimum [Member]
Expected life in years		6 years	5 years 6 months	6 years

Stock Option Activity Under Stock Option Plan (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Number of Shares
Beginning Balance			6,840,719
Granted	41,500	153,000	4,395,438	1,049,000
Exercised			(363,109)
Cancelled			(686,219)
Ending Balance	10,186,829		10,186,829		6,840,719
Options exercisable, at end of period	4,970,314		4,970,314		3,596,315
Options available for future grant	1,427,152		1,427,152
Weighted Average Exercise Price
Beginning Balance			$ 3.81
Granted			3.79
Exercised			2.86
Cancelled			3.86
Ending Balance	$ 3.83		3.83		$ 3.81
Options exercisable, at end of period	$ 4.13		$ 4.13		$ 4.17
Weighted Average Contractual Term (Years)
Outstanding, at end of period			8 years 3 months 7 days
Options exercisable, at end of period			7 years 2 months 23 days		6 years 10 months 24 days
Aggregate Intrinsic Value
Outstanding, at end of period	$ 899		$ 899
Options exercisable, at end of period	$ 771		$ 771		$ 598

Summary of Non-Vested Restricted Stock (Detail) - Non Vested Restricted Stock Member	6 Months Ended
	Jun. 30, 2021 $ / shares shares
Number of Shares
Beginning Balance \| shares	786,280
Granted \| shares	726,224
Vested \| shares	(325,238)
Cancelled \| shares	(122,091)
Ending Balance \| shares	1,065,175
Weighted Average Grant Date Fair Value
Beginning Balance \| $ / shares	$ 3.08
Granted \| $ / shares	3.75
Vested \| $ / shares	3.58
Cancelled \| $ / shares	3.61
Ending Balance \| $ / shares	$ 3.32

Warrants - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
	Sep. 12, 2019	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Fair Value Assumptions Expected volatility Rate Maximum			73.90%	74.80%	73.74%
Fair Value Assumptions Risk Free Interest Rate Maximum			0.60%	1.15%	1.68%
Fair Value Assumptions Expected Term1		6 years 3 months
Fair Value Assumptions Expected Dividend Rate		0.00%	0.00%	0.00%	0.00%
Net Proceeds from Underwriting					$ 13,015
Proceeds from private placement	$ 52,500
MD Anderson Warrant [Member]
Number of securities into which the class of warrant converted		3,333,333		3,333,333
Warrant exercise per share		$ 0.001		$ 0.001
fair value of adjustment of warrants				$ 14,500
Warrant Expiry date		Dec. 31, 2026		Dec. 31, 2026
Securities Purchase Agreement [Member]
Net Proceeds from Underwriting				$ 47,100
Private Placement [Member]
Number of securities into which the class of warrant converted	17,803,031	18,939,394		18,939,394
Warrant exercise per share	$ 3.01	$ 3.01		$ 3.01
fair value of adjustment of warrants				$ 18,400
Fair Value Assumptions Expected volatility Rate Maximum				71.00%
Fair Value Assumptions Risk Free Interest Rate Maximum				2.99%
Fair Value Assumptions Expected Term1				5 years
Fair Value Assumptions Expected Dividend Rate				0.00%
Placement agent fees and other expenses	$ 1,100
Private Placement [Member] \| New Warrants [Member]
Number of securities into which the class of warrant converted	17,803,031
Warrant exercise per share	$ 7.00
Non-cash inducement warrant expense				$ 60,800

Joint Venture - Additional Information (Detail) - USD ($) $ in Thousands	Jul. 05, 2019	Jun. 30, 2021	Dec. 31, 2020	Jan. 03, 2019
Subsidiary or Equity Method Investee [Line Items]
Common stock, shares issued		215,559,148	214,591,906
Eden Bio Cell [Member]
Subsidiary or Equity Method Investee [Line Items]
Equity method investments		$ 0
Tri Arm [Member] \| Eden Bio Cell [Member]
Subsidiary or Equity Method Investee [Line Items]
Equity interest in affilated entity	50.00%
Tri Arm [Member] \| License Agreement Terms [Member] \| Eden Bio Cell [Member]
Subsidiary or Equity Method Investee [Line Items]
Milestone payment made	$ 10,000
Share Subscription Agreement [Member] \| Ziopharm [Member] \| Eden Bio Cell [Member]
Subsidiary or Equity Method Investee [Line Items]
Common stock, shares issued				10,000,000
Share Subscription Agreement [Member] \| Tri Arm [Member] \| Eden Bio Cell [Member]
Subsidiary or Equity Method Investee [Line Items]
Common stock, shares issued				10,000,000

Subsequent Events - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Aug. 06, 2021
Subsequent Event [Line Items]
Description of payment terms	The term loan amortization date is April 1, 2022; provided, however, if the Company raises $50M in funding on or prior to March 31, 2022, the term loan first payment date shall automatically be extended to September 1, 2022. Further, if the Company raised $50M on or prior to March 31, 2022 and an additional $50M on or prior to August 31, 2022, the term loan amortization shall automatically be extended to September 1, 2023. The term loan maturity date is March 1, 2023; provided, however, if Company achieves the funding milestones, the term loan maturity date shall automatically be extended to August 1, 2025. There is a final payment due of 5.75%.
Forecast [Member] \| Term Loan [Member]
Subsequent Event [Line Items]
Initial term loan		$ 25.0
Additonal tranche facility		$ 25.0