UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549


                                  SCHEDULE 13G


                  UNDER THE SECURITIES EXCHANGE ACT OF 1934(1)


                             ZIOPHARM ONCOLOGY, INC.
                                (Name of Issuer)

                          COMMON STOCK, $.001 PAR VALUE
                         (Title of Class of Securities)

                                    98973P101
                                 (CUSIP Number)

                                   MAY 3, 2006
             (Date of Event Which Requires Filing of this Statement)


            Check the appropriate box to designate the rule pursuant
                        to which this Schedule is filed:

                                |_| Rule 13d-1(b)

                                |X| Rule 13d-1(c)

                                |_| Rule 13d-1(d)


- ------------------

         (1)  The  remainder  of this  cover  page  shall  be  filled  out for a
reporting person's initial filing on this form with respect to the subject class
of securities,  and for any subsequent  amendment  containing  information which
would alter the disclosures provided in a prior cover page.

              The information required in the remainder of this cover page shall
not be deemed to be "filed"  for the  purpose  of  Section 18 of the  Securities
Exchange Act of 1934 or otherwise  subject to the liabilities of that section of
the Act but shall be subject to all other  provisions of the Act  (however,  SEE
the NOTES).


CUSIP No. 98973P101 13G Page 2 of 10 Pages - --------- ---------------------------------------------------------------------- 1. NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) ProQuest Investments III, L.P. 20-0992411 - --------- ---------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP** (a) | | (b) |X| - --------- ---------------------------------------------------------------------- 3. SEC USE ONLY - --------- ---------------------------------------------------------------------- 4. CITIZENSHIP OR PLACE OF ORGANIZATION Delaware - --------------------------- ---------------------------------------------------- 5. SOLE VOTING POWER NUMBER OF -0- SHARES --------- ---------------------------------------------------- 6. SHARED VOTING POWER BENEFICIALLY 1,403,888 OWNED BY --------- ---------------------------------------------------- 7. SOLE DISPOSITIVE POWER EACH -0- REPORTING --------- ---------------------------------------------------- 8. SHARED DISPOSITIVE POWER PERSON WITH 1,403,888 - --------- ---------------------------------------------------------------------- 9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,403,888 - --------- ---------------------------------------------------------------------- 10. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES** |_| - --------- ---------------------------------------------------------------------- 11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 9.01% - --------- ---------------------------------------------------------------------- 12. TYPE OF REPORTING PERSON** PN - --------- ---------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT

CUSIP No. 98973P101 13G Page 3 of 10 Pages - --------- ---------------------------------------------------------------------- 1. NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) ProQuest Associates III LLC 20-0992451 - --------- ---------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP** (a) | | (b) |X| - --------- ---------------------------------------------------------------------- 3. SEC USE ONLY - --------- ---------------------------------------------------------------------- 4. CITIZENSHIP OR PLACE OF ORGANIZATION Delaware - --------------------------- ---------------------------------------------------- 5. SOLE VOTING POWER NUMBER OF -0- SHARES --------- ---------------------------------------------------- 6. SHARED VOTING POWER BENEFICIALLY 1,403,888 OWNED BY --------- ---------------------------------------------------- 7. SOLE DISPOSITIVE POWER EACH -0- REPORTING --------- ---------------------------------------------------- 8. SHARED DISPOSITIVE POWER PERSON WITH 1,403,888 - --------- ---------------------------------------------------------------------- 9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,403,888 - --------- ---------------------------------------------------------------------- 10. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES** |_| - --------- ---------------------------------------------------------------------- 11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 9.01% - --------- ---------------------------------------------------------------------- 12. TYPE OF REPORTING PERSON** OO - --------- ---------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT

CUSIP No. 98973P101 13G Page 4 of 10 Pages - --------- ---------------------------------------------------------------------- 1. NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Jay Moorin - --------- ---------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP** (a) | | (b) |X| - --------- ---------------------------------------------------------------------- 3. SEC USE ONLY - --------- ---------------------------------------------------------------------- 4. CITIZENSHIP OR PLACE OF ORGANIZATION United States - --------------------------- ---------------------------------------------------- 5. SOLE VOTING POWER NUMBER OF -0- SHARES --------- ---------------------------------------------------- 6. SHARED VOTING POWER BENEFICIALLY 1,403,888 OWNED BY --------- ---------------------------------------------------- 7. SOLE DISPOSITIVE POWER EACH -0- REPORTING --------- ---------------------------------------------------- 8. SHARED DISPOSITIVE POWER PERSON WITH 1,403,888 - --------- ---------------------------------------------------------------------- 9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,403,888 - --------- ---------------------------------------------------------------------- 10. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES** |_| - --------- ---------------------------------------------------------------------- 11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 9.01% - --------- ---------------------------------------------------------------------- 12. TYPE OF REPORTING PERSON** IN - --------- ---------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT

CUSIP No. 98973P101 13G Page 5 of 10 Pages - --------- ---------------------------------------------------------------------- 1. NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Alain Schreiber - --------- ---------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP** (a) | | (b) |X| - --------- ---------------------------------------------------------------------- 3. SEC USE ONLY - --------- ---------------------------------------------------------------------- 4. CITIZENSHIP OR PLACE OF ORGANIZATION United States Resident Alien - --------------------------- ---------------------------------------------------- 5. SOLE VOTING POWER NUMBER OF -0- SHARES --------- ---------------------------------------------------- 6. SHARED VOTING POWER BENEFICIALLY 1,403,888 OWNED BY --------- ---------------------------------------------------- 7. SOLE DISPOSITIVE POWER EACH -0- REPORTING --------- ---------------------------------------------------- 8. SHARED DISPOSITIVE POWER PERSON WITH 1,403,888 - --------- ---------------------------------------------------------------------- 9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,403,888 - --------- ---------------------------------------------------------------------- 10. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES** |_| - --------- ---------------------------------------------------------------------- 11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 9.01% - --------- ---------------------------------------------------------------------- 12. TYPE OF REPORTING PERSON** IN - --------- ---------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT

CUSIP No. 98973P101 13G Page 6 of 10 Pages ITEM 1(A). NAME OF ISSUER. ZIOPHARM Oncology, Inc. (the "Company"). ITEM 1(B). ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES. The Company's principal executive offices are located at 1180 Avenue of the Americas, 19th Floor, New York, NY 10036. ITEMS 2(A). NAME OF PERSON FILING. This statement is filed on behalf of the following persons with respect to shares of common stock of the Company and stock warrants to purchase shares of common stock of the Company purchased by such persons (collectively, the "Shares") in connection with a private placement of the Company's securities: (i) ProQuest Investments III, L.P., a Delaware limited partnership ("Investments III"), with respect to Shares beneficially owned by it; (ii) ProQuest Associates III LLC, a Delaware limited liability company ("Associates III"), as General Partner of Investments III, with respect to Shares beneficially owned by Investments III; (iii) Jay Moorin, an individual and a member of Associates III ("Moorin"), with respect to Shares beneficially owned by Investments III; and (iv) Alain Schreiber, an individual and a member of Associates III ("Schreiber"), with respect to Shares beneficially owned by Investments III. The foregoing persons are hereinafter are referred to collectively as the "Reporting Persons." Any disclosures herein with respect to persons other than the Reporting Persons are made on information and belief after making inquiry to the appropriate party. ITEM 2(B). ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE. The address of the principal business office of each of the Reporting Persons is 90 Nassau Street, 5th Floor, Princeton, NJ 08542. ITEM 2(C). CITIZENSHIP. Mr. Moorin is a United States citizen. Mr. Schreiber is a United States resident alien. Investments III is a Delaware limited partnership organized under the laws of the State of Delaware. Associates III is a Delaware limited liability company organized under the laws of the State of Delaware. ITEM 2(D). TITLE OF CLASS OF SECURITIES. Common stock, par value $0.001 per share.

CUSIP No. 98973P101 13G Page 7 of 10 Pages ITEM 2(E). CUSIP NUMBER. 98973P101 ITEM 3. If this statement is filed pursuant to Rules 13d-1(b) or 13d- 2(b) or (c), check whether the person filing is a: (a) |_| Broker or dealer registered under Section 15 of the Act, (b) |_| Bank as defined in Section 3(a)(6) of the Act, (c) |_| Insurance Company as defined in Section 3(a)(19) of the Act, (d) |_| Investment Company registered under Section 8 of the Investment Company Act of 1940, (e) |_| Investment Adviser in accordance with Rule 13d-1 (b)(1)(ii)(E), (f) |_| Employee Benefit Plan or Endowment Fund in accordance with 13d-1 (b)(1)(ii)(F), (g) |_| Parent Holding Company or control person in accordance with Rule 13d-1 (b)(1)(ii)(G), (h) |_| Savings Association as defined in Section 3(b) of the Federal Deposit Insurance Act, (i) |_| Church Plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act of 1940, (j) |_| Group, in accordance with Rule 13d-1(b)(1)(ii)(J). If this statement is filed pursuant to 13d-1(c), check this box: |X| ITEM 4. OWNERSHIP. The percentages used herein are calculated based upon 15,264,248 shares issued and outstanding, as of May 3, 2006, based upon the Company's Current Report on Form 8-K dated May 3, 2006. As of the close of business on May 3, 2006, the Reporting Persons beneficially owned shares of the Company's common stock in the amounts and percentages listed below: A. PROQUEST INVESTMENTS III, L.P. (a) Amount beneficially owned: 1,403,888 (b) Percent of class: 9.01%

CUSIP No. 98973P101 13G Page 8 of 10 Pages (c) (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 1,403,888 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 1,403,888 B. PROQUEST ASSOCIATES III LLC (a) Amount beneficially owned: 1,403,888 (b) Percent of class: 9.01% (c) (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 1,403,888 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 1,403,888 C. JAY MOORIN (a) Amount beneficially owned: 1,403,888 (b) Percent of class: 9.01% (c) (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 1,403,888 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 1,403,888 D. ALAIN SCHREIBER (a) Amount beneficially owned: 1,403,888 (b) Percent of class: 9.01% (c) (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 1,403,888 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 1,403,888

CUSIP No. 98973P101 13G Page 9 of 10 Pages ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS. If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following. |_| ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON. To the knowledge of the Reporting Persons, no other person has the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, a number of the Shares which represents more than five percent of the number of outstanding shares of the Shares. ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY. Not Applicable. ITEM 8. IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP. Not Applicable. ITEM 9. NOTICE OF DISSOLUTION OF GROUP. Not Applicable. ITEM 10. CERTIFICATIONS. Each of the Reporting Persons hereby makes the following certification: By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

CUSIP No. 98973P101 13G Page 10 of 10 Pages SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct. DATED: May 10, 2006 /s/ Pasquale DeAngelis ---------------------------------------- Pasquale DeAngelis, as a member of ProQuest Associates III LLC and on behalf of ProQuest Investments III, L.P. * ---------------------------------------- Jay Moorin, individually * ---------------------------------------- Alain Schreiber, individually *By: /s/ Pasquale DeAngelis -------------------------------------------- Pasquale DeAngelis, Attorney-in-Fact Power of attorney filed as an exhibit hereto Index Exhibit SCHEDULE 13G EXHIBIT NUMBER EXHIBIT DESCRIPTION - -------------- ------------------- 99.1 Joint Filing Agreement 99.2 Power of Attorney

                                                                    Exhibit 99.1

                             JOINT FILING AGREEMENT

     The  undersigned  hereby agree that statements on Schedules 13G and 13D and
Forms  3, 4 and 5 with  respect  to the  shares  of  common  stock  of  ZIOPHARM
Oncology,  Inc. and any  amendments  thereto  signed by each of the  undersigned
shall  be  filed  on  behalf  of  each  of the  undersigned  pursuant  to and in
accordance with the provisions of Rule 13d-1(k) promulgated under the Securities
Exchange Act of 1934, as amended. The undersigned hereby further agree that this
Joint  Filing  Agreement  may be  included as an exhibit to such  statements  or
amendments.  This  Joint  Filing  Agreement  may be  executed  in any  number of
counterparts,  all of which taken  together  shall  constitute  one and the same
instrument.


Dated: As of May 10, 2006                        PROQUEST ASSOCIATES III LLC

                                                 /S/ PASQUALE DEANGELIS
                                                 ----------------------------
                                                 Pasquale DeAngelis, a member


                                                 PROQUEST INVESTMENTS III, L.P.

                                                 BY: PROQUEST ASSOCIATES III LLC

                                                 /S/ PASQUALE DEANGELIS
                                                 ----------------------------
                                                 Pasquale DeAngelis, a member


                                                                *
                                                 ------------------------------
                                                 Jay Moorin


                                                                *
                                                 ------------------------------
                                                 Alain Schreiber



*By:        /S/ PASQUALE DEANGELIS
            ------------------------------------
            Pasquale DeAngelis, Attorney-in-Fact
            Power of Attorney filed as an exhibit hereto


                                                                    Exhibit 99.2

                                POWER OF ATTORNEY


     KNOW  ALL  MEN BY  THESE  PRESENTS,  that  each of the  undersigned  hereby
constitutes and appoints, as of the date hereof, Pasquale DeAngelis,  his or her
true and lawful attorney-in-fact with full power of substitution, resubstitution
and revocation,  for the undersigned and in the  undersigned's  name,  place and
stead,  in  any  and  all  capacities,   including,  but  not  limited  to,  the
undersigned's  individual capacity and the undersigned's capacity as a member of
ProQuest  Associates III LLC, a Delaware limited liability company  ("Associates
III"), to execute all agreements,  certificates,  forms,  instruments,  or other
documents,  and to take  any  action,  necessary  to file  beneficial  ownership
reports on Schedules 13D and 13G and Forms 3, 4 and 5 (including  any amendments
thereto,  and including any beneficial ownership reports which may in the future
be required by the Securities and Exchange  Commission to be filed provided that
the purpose and form of such reports is  substantially  similar to Schedules 13D
or 13G or Form 3, 4 or 5) under  the  Securities  Exchange  Act of 1934 with the
Securities and Exchange  Commission or any stock exchange or similar  authority,
in connection with any equity investments in ZIOPHARM Oncology,  Inc. by each of
the undersigned in his or her individual  capacity and by each of Associates III
and  ProQuest  Investments  III,  L.P.  ("Investments  III"  and  together  with
Associates III, the "Companies").

     In connection  with the appointment of such  attorney-in-fact,  each of the
undersigned hereby grants unto said attorney-in-fact full power and authority to
do and  perform  each and every  act and thing  which,  in the  opinion  of such
attorney-in-fact,  may be requisite,  necessary, proper or of benefit to be done
in and  about  the  premises,  as  fully  to all  intents  and  purposes  as the
undersigned  might or could do in person,  thereby  ratifying and confirming all
that said  attorney-in-fact (or  attorney-in-fact's  substitute or substitutes),
may lawfully do or cause to be done by virtue hereof,  it being  understood that
the documents  executed by such  attorney-in-fact  on behalf of the  undersigned
pursuant to this Power of Attorney  shall be in such form and shall contain such
terms and conditions as such attorney-in-fact may approve in his own discretion.
Each of the undersigned  acknowledges  that the foregoing  attorney-in-fact,  in
serving in such capacity at the request of the undersigned,  is not assuming any
of the undersigned's or the Companies'  responsibilities  to comply with Section
13 or Section 16 of the Securities Exchange Act of 1934.

Dated:  As of May 10, 2006
                                                /S/ JAY MOORIN
                                                --------------
                                                Jay Moorin




                                                /S/ ALAIN SCHREIBER
                                                -------------------
                                                Alain Schreiber