Exhibit 10.24





REGISTRATION RIGHTS AGREEMENT




This Registration Rights Agreement (this “Agreement”) is made and entered into as of January 12, 2011, by and among ZIOPHARM Oncology, Inc., a Delaware corporation (the “Company”), and Intrexon Corporation, a Virginia corporation (“Intrexon”).




This Agreement is being entered into pursuant to the Stock Purchase Agreement between the Company and Intrexon dated as of January 6, 2011 (the “Purchase Agreement”).




The Company and Intrexon hereby agree as follows:




1.           Definitions.




Capitalized terms used and not otherwise defined herein shall have the meanings given such terms in the Purchase Agreement.  As used in this Agreement, the following terms shall have the following meanings:




“Affiliate” means, with respect to any Person, any other Person that directly or indirectly controls or is controlled by or under common control with such Person.  For the purposes of this definition, “control,” when used with respect to any Person, means the possession, directly or indirectly, of the power to direct or cause the direction of the management and policies of such Person, whether through the ownership of voting securities, by contract or otherwise; and the terms of “affiliated,”
“controlling” and “controlled” have meanings correlative to the foregoing.




“Board” means the Company’s Board of Directors.




“Business Day” means any day except Saturday, Sunday and any day which shall be a legal holiday or a day on which banking institutions in the state of Delaware generally are authorized or required by law or other government actions to close.




“Closing Date” means the date of the closing of the purchase and sale of the Shares pursuant to the Purchase Agreement.




“Commission” means the Securities and Exchange Commission.




“Common Stock” means the Company’s Common Stock, par value $0.001 per share.




“Effectiveness Period” shall have the meaning set forth in Section 2.




“Exchange Act” means the Securities Exchange Act of 1934, as amended.




“Filing Date” means May 11, 2011.




“Holder” or “Holders” means the holder or holders, as the case may be, from time to time of Registrable Securities.









“Indemnified Party” shall have the meaning set forth in Section 5(c).




“Indemnifying Party” shall have the meaning set forth in Section 5(c).




“Losses” shall have the meaning set forth in Section5(a).




“Person” means an individual or a corporation, partnership, trust, incorporated or unincorporated association, joint venture, limited liability company, joint stock company, government (or an agency or political subdivision thereof) or other entity of any kind.




“Proceeding” means an action, claim, suit, investigation or proceeding (including, without limitation, an investigation or partial proceeding, such as a deposition), whether commenced or threatened.




“Prospectus” means the prospectus included in the Registration Statement (including, without limitation, a prospectus that includes any information previously omitted from a prospectus filed as part of an effective registration statement in reliance upon Rule 430A promulgated under the Securities Act), as amended or supplemented by any prospectus supplement, with respect to the terms of the offering of any portion of the Registrable Securities covered by the Registration Statement, and all other amendments and supplements to the Prospectus, including post-effective amendments, and all material incorporated by reference in such
Prospectus.




“Registrable Securities” means the First Tranche Shares, Second Tranche Shares and Upfront Purchase Shares (as such terms are defined in the Purchase Agreement) issued or issuable to Intrexon and any securities issued with respect to, or in exchange for or in replacement of such shares of Common Stock upon any stock split, stock dividend, recapitalization, subdivision, merger or similar event; provided, however, that the applicable Holder has completed and delivered to the Company a Selling Stockholder Questionnaire; and provided further that such securities shall no longer be deemed Registrable Securities if such securities have been sold
pursuant to a Registration Statement, or (ii) such shares have been sold in compliance with Rule 144 or all such shares may be sold without limitation pursuant to Rule 144.




“Registration Statement” means the registration statements and any additional registration statements contemplated by Section 2, including (in each case) the Prospectus, amendments and supplements to such registration statement or Prospectus, including pre- and post-effective amendments, all exhibits thereto, and all material incorporated by reference in such registration statement.




“Rule 144” means Rule 144 promulgated by the Commission pursuant to the Securities Act, as such Rule may be amended from time to time, or any similar rule or regulation hereafter adopted by the Commission having substantially the same effect as such Rule.




“Rule 415” means Rule 415 promulgated by the Commission pursuant to the Securities Act, as such Rule may be amended from time to time, or any similar rule or regulation hereafter adopted by the Commission having substantially the same effect as such Rule.




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“Securities Act” means the Securities Act of 1933, as amended.




“Selling Stockholder Questionnaire” means a questionnaire in the form attached as Annex B hereto, or such other form of questionnaire as may reasonably be requested by the Company from time to time.




2.           Registration Obligations; Filing Date Registration.  On or prior to the Filing Date the Company shall prepare and file with the Commission a Registration Statement covering the resale of the Registrable Securities as would permit or facilitate the sale and distribution of all the Registrable Securities in the manner reasonably requested by the Holder; provided, however, that if the Filing Date falls on a day that is not a Business Day, such deadline shall be extended to the next Business Day.  The Registration Statement shall be on Form S-3 (except if the Company is
not then eligible to register for resale the Registrable Securities on Form S-3, in which case such registration shall be on another appropriate form in accordance with the Securities Act and the rules promulgated thereunder and the Company shall undertake to register the Registrable Securities on Form S-3 as soon as practicable following the availability of such form, provided that the Company shall use reasonable best efforts to maintain the effectiveness of the Registration Statement then in effect until such time as a Registration Statement on Form S-3 covering the Registrable Securities has been declared effective by the Commission).  The Registration Statement shall contain the “Plan of Distribution” section in substantially the form attached hereto as Annex A.  The Company shall use reasonable best efforts to cause the Registration Statement to be
declared effective under the Securities Act as promptly as practicable after the filing thereof, and, subject to Section 3(j) hereof, to keep such Registration Statement continuously effective under the Securities Act until such date as is the earlier of (x) the date when all Registrable Securities covered by such Registration Statement have been sold under such Registration Statement; or (y) the date on which the Registrable Securities may be sold pursuant to Rule 144, without limitations, as determined by the counsel to the Company pursuant to a written opinion letter, addressed to the Company’s transfer agent to such effect (the “Effectiveness Period”). By 9:30 am Eastern Time on the Business Day following the Effective Date, the Company shall file with the Commission in accordance with Rule 424 under the
Securities Act the final prospectus to be used in connection with sales pursuant to such Registration Statement.  Intrexon acknowledges and agrees that securities other than the Registrable Securities may be included in the Registration Statement.




3.           Registration Procedures.




In connection with the Company’s registration obligations hereunder, the Company shall:




(a)           Prepare and file with the Commission on or prior to the Filing Date, a Registration Statement on Form S-3 (or if the Company is not then eligible to register for resale the Registrable Securities on Form S-3 such registration shall be on another appropriate form in accordance with the Securities Act and the rules and regulations promulgated thereunder) in accordance with the method or methods of distribution thereof as described on Annex A hereto (except if otherwise directed by all of the Holders), and use reasonable best efforts to cause the Registration Statement to become effective and remain effective as provided herein.




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(b)           Prepare and file with the Commission such amendments, including post-effective amendments, to the Registration Statement as may be necessary to keep the Registration Statement continuously effective (subject to Section 3(l)) as to the applicable Registrable Securities for the Effectiveness Period and prepare and file with the Commission such additional Registration Statements, if necessary, in order to register for resale under the Securities Act all of the Registrable Securities; (ii) cause the related Prospectus to be amended or supplemented by any required Prospectus supplement, and as so supplemented or amended to be filed pursuant to Rule
424 (or any similar provisions then in force) promulgated under the Securities Act; (iii) respond promptly to any comments received from the Commission with respect to the Registration Statement or any amendment thereto and promptly provide the Holders true and complete copies of all correspondence from and to the Commission relating to the Registration Statement; and (iv) comply in all material respects with the provisions of the Securities Act and the Exchange Act with respect to the disposition of all Registrable Securities covered by the Registration Statement during the applicable period in accordance with the intended methods of disposition by the Holders thereof set forth in the Registration Statement as so amended or in such Prospectus as so supplemented.




(c)           Promptly notify the Holders of Registrable Securities (i)(A) when a Prospectus or any Prospectus supplement or post-effective amendment to the Registration Statement is filed; (B) when the Commission notifies the Company whether there will be a “review” of such Registration Statement and whenever the Commission comments in writing on such Registration Statement, and if requested by such Holders, furnish to them a copy of such comments and the Company’s responses thereto; and (C) with respect to the Registration Statement or any post-effective amendment, when the same has become effective; (ii) of any request by the Commission
or any other Federal or state governmental authority for amendments or supplements to the Registration Statement or Prospectus or for additional information; (iii) of the issuance by the Commission of any stop order suspending the effectiveness of the Registration Statement covering any or all of the Registrable Securities or the initiation of any Proceedings for that purpose; (iv) of the receipt by the Company of any notification with respect to the suspension of the qualification or exemption from qualification of any of the Registrable Securities for sale in any jurisdiction, or the initiation or threatening of any Proceeding for such purpose; and (v) of the occurrence of any event that makes any statement made in the Registration Statement or Prospectus or any document incorporated or deemed to be incorporated therein by reference untrue in any material respect or that requires any
revisions to the Registration Statement, Prospectus or other documents so that, in the case of the Registration Statement or the Prospectus, as the case may be, it will not contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading.




(d)           Use reasonable best efforts to avoid the issuance of, or, if issued, obtain the withdrawal of, (i) any order suspending the effectiveness of the Registration Statement or (ii) any suspension of the qualification (or exemption from qualification) of any of the RegistrableSecurities for sale in any U.S. jurisdiction.




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(e)           If requested by the Holders of a majority of the Registrable Securities, (i) promptly incorporate in a Prospectus supplement or post-effective amendment to the Registration Statement such information as the Company reasonably agrees should be included therein and (ii) make all required filings of such Prospectus supplement or such post-effective amendment as soon as practicable after the Company has received notification of the matters to be incorporated in such Prospectus supplement or post-effective amendment.




(f)           Furnish to each Holder, without charge and upon request, at least one conformed copy of each Registration Statement and each amendment thereto, including financial statements and schedules, and, to the extent requested by such Person, all documents incorporated or deemed to be incorporated therein by reference, and all exhibits (including those previously furnished or incorporated by reference) promptly after the filing of such documents with the Commission.




(g)           Promptly deliver to each Holder, without charge, as many copies of the Prospectus or Prospectuses (including each form of prospectus) and each amendment or supplement thereto as such Persons may reasonably request; and the Company hereby consents to the use of such Prospectus and each amendment or supplement thereto by each of the selling Holders in connection with the offering and sale of the Registrable Securities covered by such Prospectus and any amendment or supplement thereto.




(h)           Prior to any public offering of Registrable Securities, use commercially reasonable efforts to register or qualify or cooperate with the selling Holders in connection with the registration or qualification (or exemption from such registration or qualification) of such Registrable Securities for offer and sale under the securities or Blue Sky laws of such jurisdictions within the United States as any Holder reasonably requests in writing, to keep each such registration or qualification (or exemption therefrom) effective during the Effectiveness Period and to do any and all other acts or things necessary or advisable to enable the disposition in
such jurisdictions of the Registrable Securities covered by a Registration Statement; provided, however, the Company shall in no event be required to (x) qualify to do business in any state where it is not then qualified or (y) take any action that would subject it to tax or to the general service of process in any such state where it is not then subject, or (z) comply with state securities or “blue sky” laws of any state for which registration by coordination is unavailable to the Company.




(i)            Cooperate with the Holders to facilitate the timely preparation and delivery of certificates representing Registrable Securities to be sold pursuant to a Registration Statement.




(j)            Upon the occurrence of any event contemplated by Section 3(c)(v), promptly prepare a supplement or amendment, including a post-effective amendment, to the Registration Statement or a supplement to the related Prospectus or any document incorporated or deemed to be incorporated therein by reference, and file any other required document so that, as thereafter delivered, neither the Registration Statement nor such Prospectus will contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein, in the light of the circumstances under which they were made, not
misleading.




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(k)           Use commercially reasonable efforts to cause all Registrable Securities relating to the Registration Statement to be listed on the Nasdaq Stock Market or any subsequent securities exchange, quotation system or market, if any, on which similar securities issued by the Company are then listed or traded.




(l)            The Company may require each selling Holder to furnish to the Company information regarding such Holder and the distribution of such Registrable Securities as is required by law to be disclosed in the Registration Statement, and the Company may exclude from such registration the Registrable Securities of any such Holder who fails to furnish such information within fifteen (15) days after receiving such request.




Each Holder covenants and agrees that (i) it will not sell any Registrable Securities under the Registration Statement until it has received copies of the Prospectus as then amended or supplemented as contemplated in Section 3(g) and notice from the Company that such Registration Statement and any post-effective amendments thereto have become effective as contemplated by Section 3(c) and (ii) it and its officers, directors or Affiliates, if any, will comply with the prospectus delivery requirements of the Securities Act as applicable to them in connection with sales of Registrable Securities pursuant to the Registration Statement.




Each Holder agrees by its acquisition of such Registrable Securities that, upon receipt of a notice from the Company of the occurrence of any event of the kind described in Section 3(c)(ii), 3(c)(iii), 3(c)(iv), 3(c)(v) or 3(m), such Holder will forthwith discontinue disposition of such Registrable Securities under the Registration Statement until such Holder’s receipt of the copies of the supplemented Prospectus and/or amended Registration Statement contemplated by Section 3(j), or until it is advised in writing by the Company that the use of the applicable Prospectus may be resumed, and, in either case, has received copies of any additional or supplemental filings that are incorporated or deemed to be
incorporated by reference in such Prospectus or Registration Statement.




(m)          If (i) there is material non-public information regarding the Company which the Board reasonably determines not to be in the Company’s best interest to disclose and which the Company is not otherwise required to disclose, or (ii) there is a significant business opportunity (including, but not limited to, the acquisition or disposition of assets (other than in the ordinary course of business) or any merger, consolidation, tender offer or other similar transaction) available to the Company which the Board reasonably determines not to be in the Company’s best interest to disclose, then the Company may postpone or suspend filing or
effectiveness of a registration statement for a period not to exceed thirty (30) consecutive days, provided that the Company may not postpone or suspend its obligation under this Section 3(m) for more than sixty (60) days in the aggregate during any 12 month period; provided, however, that no such postponement or suspension shall be permitted for consecutive thirty (30) day periods, arising out of the same set of facts, circumstances or transactions.




(n)           Any legend indicating, directly or indirectly, that the Registrable Securities constitute “restricted securities” (as such term is defined in Rule 144) stamped on a certificate evidencing the Registrable Securities, and the related stock transfer instructions and record notations with respect to such Registrable Securities, shall be removed and the Company shall approve the issuance of a certificate without such legend to the holder of such Securities if the Holder thereof provides the Company with reasonable assurances that such securities can be sold pursuant to Rule 144.  Following the receipt by the Company of such
assurances, the Company will, no later than five trading days following the delivery by a holder to the Company or the Company’s transfer agent of a legended certificate representing such securities, deliver or cause to be delivered to such Holder a certificate representing such securities that is free from all restrictive and other legends.




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4.           Registration Expenses.




All reasonable fees and expenses incident to the performance of or compliance with this Agreement by the Company (excluding underwriters’ discounts and commissions and all fees and expenses of legal counsel, accountants and other advisors for any Holder except as specifically provided below), except as and to the extent specified in this Section 4, shall be borne by the Company whether or not the Registration Statement is filed or becomes effective and whether or not any Registrable Securities are sold pursuant to the Registration Statement.  The fees and expenses referred to in the foregoing sentence shall include, without limitation, (i) all registration and filing fees (including, without
limitation, fees and expenses (A) with respect to filings required to be made with the Nasdaq Stock Market and each other securities exchange or market on which Registrable Securities are required hereunder to be listed, (B) with respect to filings required to be made with the Financial Industry Regulatory Authority and (C) in compliance with state securities or Blue Sky laws, (ii) messenger, telephone and delivery expenses, (iii) fees and disbursements of counsel for the Company, (iv) Securities Act liability insurance, if the Company so desires such insurance, and (v) fees and expenses of all other Persons retained by the Company in connection with the consummation of the transactions contemplated by this Agreement, including, without limitation, the Company’s independent public accountants.  In addition, the Company shall be responsible for all of its internal
expenses incurred in connection with the consummation of the transactions contemplated by this Agreement (including, without limitation, all salaries and expenses of its officers and employees performing legal or accounting duties), the expense of any annual audit, the fees and expenses incurred in connection with the listing of the Registrable Securities on any securities exchange as required hereunder.




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5.           Indemnification.




(a)           Indemnification by the Company.  The Company shall, notwithstanding any termination of this Agreement, indemnify and hold harmless each Holder, its permitted assignees, officers, directors, agents, brokers (including brokers who offer and sell Registrable Securities as principal as a result of a pledge or any failure to perform under a margin call of Common Stock), underwriters, investment advisors and employees, each Person who controls any such Holder or permitted assignee (within the meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act) and the
officers, directors, agents and employees of each such controlling Person, and the respective successors, assigns, estate and personal representatives of each of the foregoing, to the fullest extent permitted by applicable law, from and against any and all claims, losses, damages, liabilities, penalties, judgments, costs (including, without limitation, costs of investigation) and expenses (including, without limitation, reasonable attorneys’ fees and expenses) (collectively, “Losses”), arising out of or relating to any untrue or alleged untrue statement of a material fact contained in the Registration Statement, any Prospectus, as supplemented or amended, if applicable, or arising out of or relating to any omission or alleged omission of a material fact required to be stated therein or necessary to make the
statements therein (in the case of any Prospectus or form of prospectus or supplement thereto, in the light of the circumstances under which they were made) not misleading, except (i) to the extent, but only to the extent, that such untrue statements or omissions are based upon information regarding such Holder furnished in writing to the Company by such Holder expressly for use in the Registration Statement, such Prospectus or such form of Prospectus or in any amendment or supplement thereto  (it being understood that each Holder has approved Annex A hereto for this purpose); (ii) as a result of the failure of such Holder to deliver a Prospectus, as amended or supplemented, to a purchaser in connection with an offer or sale; or (iii) in the case of an occurrence of an event of the type specified in Section 3(c)(ii)-(v), the use by a Holder of an outdated or defective
Prospectus after the Company has notified such Holder in writing that the Prospectus is outdated or defective and prior to the receipt by such Holder of notice that use of the applicable prospectus may be resumed (and, if applicable, receipt of additional or supplemental filings that are incorporated or deemed to be incorporated by referenced in such Prospectus or Registration Statement), but only if and to the extent that following such receipt the misstatement or omission giving rise to such Loss would have been corrected; provided, however, that the indemnity agreement contained in this Section 5(a) shall not apply to amounts paid in settlement of any Losses if such settlement is effected without the prior written consent of the Company, which consent shall not be unreasonably withheld.  The Company shall notify such Holder promptly of the institution, threat or assertion
of any Proceeding of which the Company is aware in connection with the transactions contemplated by this Agreement.  Such indemnity shall remain in full force and effect regardless of any investigation made by or on behalf of an Indemnified Party (as defined in Section 5(c) hereof) and shall survive the transfer of the Registrable Securities by the Holder.




(b)           Indemnification by Holders.  Each Holder and its permitted assignees shall, severally and not jointly, indemnify and hold harmless the Company, its directors, officers, agents and employees, each Person who controls the Company (within the meaning of Section 15 of the Securities Act and Section 20 of the Exchange Act), and the directors, officers, agents or employees of such controlling Persons, and the respective successors, assigns, estate and personal representatives of each of the foregoing, to the fullest extent permitted by applicable law, from and against all
Losses, as incurred, arising out of or relating to any untrue or alleged untrue statement of a material fact contained in the Registration Statement, any Prospectus, as supplemented or amended, if applicable, or arising out of or relating to any omission or alleged omission of a material fact required to be stated therein or necessary to make the statements therein (in the case of any Prospectus or supplement thereto, in the light of the circumstances under which they were made) not misleading, to the extent, but only to the extent, that such untrue statement or omission is contained in or omitted from any information regarding such Holder furnished in writing to the Company by such Holder expressly for use therein, and that such information was reasonably relied upon by the Company for use therein, or to the extent that such information relates to such Holder or such Holder’s
proposed method of distribution of Registrable Securities and was furnished in writing by such Holder expressly for use therein (it being understood that each Holder has approved Annex A hereto for this purpose).  Notwithstanding anything to the contrary contained herein, in no event shall the liability of any Person under this Section 5(b) exceed the net proceeds to such Person as a result of the sale of Registrable Securities pursuant to a Registration Statement in connection with which the untrue or alleged untrue statement or material omission was provided.




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(c)           Conduct of Indemnification Proceedings.  If any Proceeding shall be brought or asserted against any Person entitled to indemnity hereunder (an “Indemnified Party”), such Indemnified Party promptly shall notify the Person from whom indemnity is sought (the “Indemnifying Party”) in writing, and the Indemnifying Party shall assume the defense thereof, including the employment of counsel reasonably satisfactory to the Indemnified Party and
the payment of all fees and expenses incurred in connection with defense thereof; provided, that the failure of any Indemnified Party to give such notice shall not relieve the Indemnifying Party of its obligations or liabilities pursuant to this Agreement, except (and only) to the extent that it shall be finally determined by a court of competent jurisdiction (which determination is not subject to appeal or further review) that such failure shall have proximately and materially adversely prejudiced the Indemnifying Party.




An Indemnified Party shall have the right to employ separate counsel in any such Proceeding and to participate in the defense thereof, but the fees and expenses of such counsel shall be at the expense of such Indemnified Party or Parties unless: (1) the Indemnifying Party has agreed in writing to pay such fees and expenses; or (2) the Indemnifying Party shall have failed promptly to assume the defense of such Proceeding and to employ counsel reasonably satisfactory to such Indemnified Party in any such Proceeding; or (3) the named parties to any such Proceeding (including any impleaded parties) include both such Indemnified Party and the Indemnifying Party, and such Indemnified Party shall have been advised by
counsel (which shall be reasonably acceptable to the Indemnifying Party) that a conflict of interest is likely to exist if the same counsel were to represent such Indemnified Party and the Indemnifying Party (in which case, the Indemnifying Party shall be responsible for reasonable fees and expenses of no more than one counsel for the Indemnified Parties).  The Indemnifying Party shall not be liable for any settlement of any such Proceeding effected without its written consent, which consent shall not be unreasonably withheld or delayed.  No Indemnifying Party shall, without the prior written consent of the Indemnified Party, effect any settlement of any pending Proceeding in respect of which any Indemnified Party is a party, unless such settlement includes an unconditional release of such Indemnified Party from all liability on claims that are the subject matter of
such Proceeding.




All fees and expenses of the Indemnified Party (including reasonable fees and expenses to the extent incurred in connection with investigating or preparing to defend such Proceeding in a manner not inconsistent with this Section) shall be paid to the Indemnified Party, as incurred, within twenty (20) Business Days of written notice thereof to the Indemnifying Party (regardless of whether it is ultimately determined that an Indemnified Party is not entitled to indemnification hereunder;provided, that the Indemnifying Party may require such Indemnified Party to undertake to reimburse all such fees and expenses to the extent it is finally judicially
determined that such Indemnified Party is not entitled to indemnification hereunder).




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(d)           Contribution.  If a claim for indemnification under Section 5(a) or 5(b) is unavailable to an Indemnified Party because of a failure or refusal of a governmental authority to enforce such indemnification in accordance with its terms (by reason of public policy or otherwise), then each Indemnifying Party, in lieu of indemnifying such Indemnified Party, shall contribute to the amount paid or payable by such Indemnified Party as a result of such Losses, in such proportion as is appropriate to reflect the relative fault of the Indemnifying Party and Indemnified Party in
connection with the actions, statements or omissions that resulted in such Losses as well as any other relevant equitable considerations.  The relative fault of such Indemnifying Party and Indemnified Party shall be determined by reference to, among other things, whether any action in question, including any untrue or alleged untrue statement of a material fact or omission or alleged omission of a material fact, has been taken or made by, or relates to information supplied by, such Indemnifying, Party or Indemnified Party, and theparties’ relative intent, knowledge, access to information and opportunity to correct or prevent such action, statement or omission.  The amount paid or payable by a party as a result of any Losses shall be deemed to include, subject to the limitations set forth in Section
5(c), any reasonable attorneys’ or other reasonable fees or expenses incurred by such party in connection with any Proceeding to the extent such party would have been indemnified for such fees or expenses if the indemnification provided for in this Section was available to such party in accordance with its terms.




The parties hereto agree that it would not be just and equitable if contribution pursuant to this Section 5(d) were determined by pro rata allocation or by any other method of allocation that does not take into account the equitable considerations referred to in the immediately preceding paragraph.  No Person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any Person who was not guilty of such fraudulent misrepresentation.




The indemnity and contribution agreements contained in this Section are in addition to any liability that the Indemnifying Parties may have to the Indemnified Parties.  Notwithstanding anything to the contrary contained herein, the Holders shall be liable under this Section 5(d) for only that amount as does not exceed the aggregate amount invested by such Holder under the Purchase Agreement.




6.           Rule 144.




As long as any Holder owns any Registrable Securities, the Company covenants to use its commercially reasonable efforts to timely file (or obtain extensions in respect thereof and file within the applicable grace period) all reports required to be filed by the Company after the date hereof pursuant to Section 13(a) or 15(d) of the Exchange Act.  As long as any Holder owns any Registrable Securities, if the Company is not required to file reports pursuant to Section 13(a) or 15(d) of the Exchange Act, it will prepare and furnish to the Holders and make publicly available in accordance with Rule 144 annual and quarterly financial statements, together with a discussion and analysis of such financial
statements in form and substance substantially similar to those that would otherwise be required to be included in reports required by Section 13(a) or 15(d) of the Exchange Act, as well as any other information required thereby, in the time period that such filings would have been required to have been made under the Exchange Act.  The Company further covenants that it will take such further action as any Holder may reasonably request, all to the extent required from time to time to enable such Person to sell the Shares without registration under the Securities Act within the limitation of the exemptions provided by Rule 144 promulgated under the Securities Act, including providing any legal opinions relating to such sale pursuant to Rule 144.  Upon the request of any Holder, the Company shall deliver to such Holder a written certification of a duly authorized
officer as to whether it has complied with such requirements.




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7.           Miscellaneous.




(a)           Remedies.  In the event of a breach by the Company or by a Holder, of any of their obligations under this Agreement, each Holder or the Company, as the case may be, in addition to being entitled to exercise all rights granted by law and under this Agreement, including recovery of damages, will be entitled to specific performance of its rights under thisAgreement.  The Company and each Holder agree that monetary damages would not provideadequate compensation for any losses incurred by reason of a breach by it of any of the provisions of this Agreement and hereby further agrees that, in the event of any action for specific performance in respect of such breach, it shall waive the defense that a remedy at law would be adequate.




(b)           Entire Agreement; Amendment.  This Agreement and the Purchase Agreement contain the entire understanding and agreement of the parties with respect to the matters covered hereby and, except as specifically set forth herein or in the Purchase Agreement, neither the Company nor any Holder make any representation, warranty, covenant or undertaking with respect to such matters, and they supersede all prior understandings and agreements with respect to said subject matter, all of which are merged herein.  No provision of this Agreement may be waived or amended other
than by a written instrument signed by the Company and the Holders of at least a majority of all Registrable Securities then outstanding.  Any amendment or waiver effected in accordance with this Section 7(b) shall be binding upon each Holder (and their permitted assigns) and the Company.




(c)           Notices.  Any notice, demand, request, waiver or other communication required or permitted to be given hereunder shall be in writing and shall be deemed to have been given when delivered if personally delivered or sent by facsimile (provided that the party providing such notice promptly confirms receipt of such transmission with the other party by telephone), on the business day after dispatch if sent by a nationally-recognized overnight courier and on the third business day following the date of mailing if sent by certified mail, postage prepaid, return receipt
requested.  The addresses for such communications shall be:




If to the Company:
ZIOPHARM Oncology, Inc.


1180 Avenue of the Americas, 19th Floor


New York, NY  10036


Attention: Chief Executive Officer


Fax No.:  (646) 214-0711





with copies (which copies


shall not constitute notice


to the Company) to:
Maslon Edelman Borman & Brand, LLP


3300 Wells Fargo Center


90 South 7th Street


Minneapolis, MN  55402


Attention: Alan M. Gilbert


Fax No.:  (612) 642-8381




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If to Intrexon:
Intrexon Corporation


20358 Seneca Meadows Parkway


Germantown, MD 20876


Attention: Legal Department


Fax No.:  (301) 556-9902





with copies (which copies


shall not constitute notice


to Intrexon) to:
Cooley LLP


3175 Hanover Street


Palo Alto, CA  94304


Attention: Robert Jones


Fax No.:  (650) 849-7400





Any party hereto may from time to time change its address for notices by giving written notice of such changed address to the other party hereto.




(d)           Waivers.  No waiver by either party of any default with respect to any provision, condition or requirement of this Agreement shall be deemed to be a continuing waiver in the future or a waiver of any other provision, condition or requirement hereof, nor shall any delay or omission of any party to exercise any right hereunder in any manner impair the exercise of any such right accruing to it thereafter.




(e)           Successors and Assigns.  This Agreement shall be binding upon and inure to the benefit of the parties and their successors and permitted assigns and shall inure to the benefit of each Holder and its successors and assigns.  The Company may not assign this Agreement or any of its rights or obligations hereunder without the prior written consent of each Holder.




(f)           Assignment of Registration Rights.  The rights of each Holder hereunder, including the right to have the Company register for resale Registrable Securities in accordance with the terms of this Agreement, shall be assignable by each Holder of all or a portionof the Registrable Securities if:  (i) the Holder agrees in writing with the transferee or assignee to assign such rights, and a copy of such agreement is furnished to the Company within a reasonable time after such assignment, (ii) the Company is,
within a reasonable time after such transfer or assignment, furnished with written notice of (a) the name and address of such transferee or assignee, and (b) the securities with respect to which such registration rights are being transferred or assigned, (iii) following such transfer or assignment the further disposition of such securities by the transferee or assignees is restricted under the Securities Act and applicable state securities laws, and (iv) at or before the time the Company receives the written notice contemplated by clause (ii) of this Section, the transferee or assignee agrees in writing with the Company to be bound by all of the provisions of this Agreement.  The rights to assignment shall apply to the Holders (and to subsequent) successors and assigns.




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(g)           Counterparts.  This Agreement may be executed in any number of counterparts, each of which when so executed shall be deemed to be an original and, all of which taken together shall constitute one and the same Agreement.  In the event that any signature is delivered by facsimile transmission, such signature shall create a valid binding obligation of the party executing (or on whose behalf such signature is executed) the same with the same force and effect as if such facsimile signature were the original thereof.




(h)           Termination.  This Agreement shall terminate on the earlier of (i) the date on which all remaining Registrable Securities may be sold without restriction pursuant to Rule 144 of the Securities Act or (ii) the date when all Registrable Securities have been sold pursuant to a Registration Statement.




(i)            Governing Law.  This Agreement shall be governed by and construed in accordance with the laws of the State of New York, without regard to principles of conflicts of law thereof.




(j)            Cumulative Remedies.  The remedies provided herein are cumulative and not exclusive of any remedies provided by law.




(k)           Severability.  The provisions of this Agreement are severable and, in the event that any court of competent jurisdiction shall determine that any one or more of the provisions or part of the provisions contained in this Agreement shall, for any reason, be held to be invalid, illegal or unenforceable in any respect, such invalidity, illegality or unenforceability shall not affect any other provision or part of a provision of this Agreement and this Agreement shall be reformed and construed as if such invalid or illegal or unenforceable provision, or part of such provision,
had never been contained herein, so that such provisions would be valid, legal and enforceable to the maximum extent possible.




(l)           Headings.  The headings herein are for convenience only, do not constitute a part of this Agreement and shall not be deemed to limit or affect any of the provisions hereof.




13




IN WITNESS WHEREOF, the parties hereto have caused this Registration Rights Agreement to be duly executed by their respective authorized officers as of the date first above written.




ZIOPHARM ONCOLOGY, INC.By:
/s/ Jonathan LewisName:
Jonathan Lewis, MD, PhDTitle:
Chief Executive OfficerINTREXON CORPORATIONBy:
/s/ Randal J. KirkName:
Randal J. KirkTitle:
Chief Executive Officer





SIGNATURE PAGE TO


REGISTRATION RIGHTS AGREEMENT







ANNEX A


PLAN OF DISTRIBUTION





The Selling Stockholders and any of their pledgees, donees, transferees, assignees or other successors-in-interest may, from time to time, sell, transfer or otherwise dispose of any or all of their shares of Common Stock or interests in shares of Common Stock on any stock exchange, market or trading facility on which the shares are traded or in private transactions.  These dispositions may be at fixed prices, at prevailing market prices at the time of sale, at prices related to the prevailing market price, at varying prices determined at the time of sale, or at negotiated prices.  The Selling Stockholders may use one or more of the following methods when disposing of the shares or interests
therein:





•
ordinary brokerage transactions and transactions in which the broker-dealer solicits purchasers;





•
block trades in which the broker-dealer will attempt to sell the shares as agent but may position and resell a portion of the block as principal to facilitate the transaction;





•
purchases by a broker-dealer as principal and resale by the broker-dealer for its account;





•
an exchange distribution in accordance with the rules of the applicable exchange;





•
privately negotiated transactions;





•
through the writing or settlement of options, swaps, derivatives or other hedging transactions, whether through an options exchange or otherwise;





•
broker-dealers may agree with the Selling Stockholders to sell a specified number of such shares at a stipulated price per share;





•
in the over the counter market;





•
a combination of any such methods of disposition; and





•
any other method permitted pursuant to applicable law.





The Selling Stockholders may also sell shares under Rule 144 under the Securities Act, if available, rather than under this prospectus.





Broker-dealers engaged by the Selling Stockholders may arrange for other broker-dealers to participate in sales.  Broker-dealers may receive commissions or discounts from the Selling Stockholders (or, if any broker-dealer acts as agent for the purchaser of shares, from the purchaser) in amounts to be negotiated, but, except as set forth in a supplement to this prospectus, in the case of an agency transaction will not be in excess of a customary brokerage commission in compliance with FINRA Rule 2440; and in the case of a principal transaction a markup or markdown in compliance with FINRA IM-2440 or the successor to such FINRA rules.





A-1




The Selling Stockholders may from time to time pledge or grant a security interest in some or all of the Shares owned by them and, if they default in the performance of their secured obligations, the pledgees or secured parties may offer and sell shares of Common Stock from time to time under the prospectus, or under an amendment to the prospectus under Rule 424(b) or other applicable provision of the Securities Act of 1933, as amended (the “Securities Act”), amending the list of selling stockholders to include the pledgee, transferee or other successors in interest as selling stockholders under the prospectus. The Selling Stockholders do not expect these commissions and discounts to exceed what is
customary in the types of transactions involved.





There can be no assurance that any Selling Stockholder will sell any or all of the shares of Common Stock pursuant to the registration statement, of which this prospectus forms a part.





The Selling Stockholders may enter into option or other transactions with broker-dealers or other financial institutions or the creation of one or more derivative securities which require the delivery to such broker-dealer or other financial institution of shares offered by the prospectus, which shares such broker-dealer or other financial institution may resell pursuant to the prospectus (as supplemented or amended to reflect such transaction).





The Selling Stockholders and any broker-dealer or agents that are involved in selling the shares of Common Stock may be deemed to be “underwriters” within the meaning of the Securities Act in connection with such sales. In such event, any commissions received by such broker-dealers or agents and any profit on the resale of Common Stock purchased by them may be deemed to be underwriting commissions or discounts under the Securities Act.  In no event shall any broker-dealer receive fees, commission and markups which, in the aggregate, would exceed eight percent (8%). Each Selling Stockholder has informed the Company that it does not have any written or oral agreement or understanding, directly or
indirectly, with any person to distribute the Common Stock.





We have advised each Selling Stockholder that it may not use shares registered on the registration statement of which this prospectus is a part to cover short sales of Common Stock made prior to the date on which the registration statement shall have been declared effective by the Securities and Exchange Commission.  If a Selling Stockholder uses this prospectus for any sale of shares of our Common Stock, it will be subject to the prospectus delivery requirements of the Securities Act. The Selling Stockholders and any other person participating in such distribution will be subject to applicable provisions of the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated
thereunder, including, without limitation, Regulation M of the Exchange Act, which may limit the timing of purchases and sales of any of the shares of Common Stock by the Selling Stockholders and any other participating person.  Regulation M may also restrict the ability of any person engaged in the distribution of the shares of Common Stock to engage in market-making activities with respect to the shares of Common Stock.  All of the foregoing may affect the marketability of the shares of Common Stock and the ability of any person or entity to engage in market-making activities with respect to the shares of Common Stock.




A-2




We may indemnify the Selling Stockholders against certain liabilities, including some liabilities under the Securities Act, in accordance with an agreement between us and the Selling Stockholders.  We may be indemnified by the Selling Stockholders against civil liabilities, including liabilities under the Securities Act, that may arise from any written information furnished to us by the Selling Stockholders specifically for use in this prospectus, in accordance with the related registration rights agreement, or we may be entitled to contribution.





A-3


Annex B




ZIOPHARM Oncology, Inc.




Selling Stockholder Notice and Questionnaire





The undersigned beneficial owner of common stock, $0.001 par value per share (the “Common Stock”), of ZIOPHARM Oncology, Inc. (the “Company”), (the “Registrable Securities”) understands that the Company has filed or intends to file with the Securities and Exchange Commission (the “Commission”) a registration statement (the “Registration
Statement”) for the registration and resale under Rule 415 of the Securities Act of 1933, as amended (the “Securities Act”), of the Registrable Securities, in accordance with the terms of the Registration Rights Agreement, dated as of  January 12, 2011 (the “Registration Rights Agreement”), between the Company and Intrexon Corporation.  The purpose of this Questionnaire is to facilitate the filing of the Registration Statement under the Securities Act that will permit you to resell the Registrable Securities in the future.  The information supplied by you will be used in preparing the Registration Statement.  All capitalized terms not otherwise defined herein shall have the meanings
ascribed thereto in the Registration Rights Agreement.




Certain legal consequences arise from being named as a selling stockholder in the Registration Statement and the related Prospectus.  Accordingly, holders and beneficial owners of Registrable Securities are advised to consult their own securities law counsel regarding the consequences of being named or not being named as a selling stockholder in the Registration Statement and the related Prospectus.




NOTICE




The undersigned beneficial owner (the “Selling Stockholder”) of Registrable Securities hereby elects to include the Registrable Securities owned by it and listed below in Item 3 (unless otherwise specified under such Item 3) in the Registration Statement.




QUESTIONNAIRE




1.
Name.




(a)
Full Legal Name of Selling Stockholder










(b)
Full Legal Name of Registered Holder (if not the same as (a) above) through which Registrable Securities Listed in Item 3 below are held:







(c)
Full Legal Name of Natural Control Person (which means a natural person who directly or indirectly alone or with others has power to vote or dispose of the securities covered by this questionnaire):









B-1





2.  Address for Notices to Selling Stockholder:







Telephone:


Fax:


Contact Person:


E-mail address of Contact Person:





3.  Beneficial Ownership of Registrable Securities:




(a)
Type and Number of Registrable Securities beneficially owned:











4.  Broker-Dealer Status:




(a)
Are you a broker-dealer?




Yes    ̈                      No    ̈




Note:
If yes, the Commission’s staff has indicated that you should be identified as an underwriter in the Registration Statement.




(b)
Are you an affiliate of a broker-dealer?




Yes    ̈                      No    ̈




Note:
If yes, provide a narrative explanation below:







(c)
If you are an affiliate of a broker-dealer, do you certify that you bought the Registrable Securities in the ordinary course of business, and at the time of the purchase of the Registrable Securities to be resold, you had no agreements or understandings, directly or indirectly, with any person to distribute the Registrable Securities?




Yes    ̈                      No    ̈




Note:
If no, the Commission’s staff has indicated that you should be identified as an underwriter in the Registration Statement.




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5.  Beneficial Ownership of Other Securities of the Company Owned by the Selling Stockholder.




Except as set forth below in this Item 5, the undersigned is not the beneficial or registered owner of any securities of the Company other than the Registrable Securities listed above in Item 3.




(a)
As of ___________, 201___, the Selling Stockholder owned outright (including shares registered in Selling Stockholder's name individually or jointly with others, shares held in the name of a bank, broker, nominee, depository or in "street name" for its account), _________ shares of the Company's capital stock (excluding the Registrable Securities).  If “zero,” please so state.




(b)
In addition to the number of shares Selling Stockholder owned outright as indicated in Item 5(a) above, as of ________________, 201___, the Selling Stockholder had or shared voting power or investment power, directly or indirectly, through a contract, arrangement, understanding, relationship or otherwise, with respect to ______________ shares of the Company's capital stock (excluding the Registrable Securities).  If “zero,” please so state.




If the answer to Item 5(b) is not “zero,” please complete the following tables:




Sole Voting Power:





Number of Shares

Nature of Relationship Resulting in Sole

Voting Power





Shared Voting Power:





Number of Shares

With Whom

Shared

Nature of

Relationship





Sole Investment power:





Number of Shares

Nature of Relationship Resulting in Sole

Investment power





Shared Investment power:





Number of Shares

With Whom

Shared

Nature of

Relationship




B-3






(c)
As of _____________, 201___, the Selling Stockholder had the right to acquire the following shares of the Company's common stock pursuant to the exercise of outstanding stock options, warrants or other rights (excluding the Registrable Securities).  Please describe the number, type and terms of the securities, the method of ownership, and whether the undersigned holds sole or shared voting and investment power.  If “none”, please so state.







6.  Relationships with the Company:




Except as set forth below, neither the undersigned nor any of its affiliates, officers, directors or principal equity holders (owners of 5% of more of the equity securities of the undersigned) has held any position or office or has had any other material relationship with the Company (or its predecessors or affiliates) during the past three years.




State any exceptions here:








7.  Plan of Distribution:




The undersigned has reviewed the form of Plan of Distribution attached asAnnex A to the Registration Rights Agreement, and hereby confirms that, except as set forth below, the information contained therein regarding the undersigned and its plan of distribution is correct and complete.




State any exceptions here:







***********




The undersigned agrees to promptly notify the Company of any inaccuracies or changes in the information provided herein that may occur subsequent to the date hereof and prior to the effective date of any applicable Registration Statement filed pursuant to the Registration Rights Agreement.




By signing below, the undersigned consents to the disclosure of the information contained herein in its answers to Items 1 through 7 and the inclusion of such information in each Registration Statement filed pursuant to the Registration Rights Agreement and each related Prospectus.  The undersigned understands that such information will be relied upon by the Company in connection with the preparation or amendment of any such Registration Statement and the related Prospectus.




B-4




By signing below, the undersigned acknowledges that it understands its obligation to comply, and agrees that it will comply, with the provisions of the Exchange Act and the rules and regulations thereunder, particularly Regulation M. The undersigned also acknowledges that it understands that the answers to this Questionnaire are furnished for use in connection with Registration Statements filed pursuant to the Registration Rights Agreement and any amendments or supplements thereto filed with the Commission pursuant to the Securities Act.




The undersigned hereby acknowledges and is advised of the following Interpretation A.65 of the July 1997 SEC Manual of Publicly Available Telephone Interpretations regarding short selling:




“An Issuer filed a Form S-3 registration statement for a secondary offering of common stock which is not yet effective.  One of the selling shareholders wanted to do a short sale of common stock “against the box” and cover the short sale with registered shares after the effective date. The issuer was advised that the short sale could not be made before the registration statement become effective, because the shares underlying the short sale are deemed to be sold at the time such sale is made.  There would, therefore, be a violation of Section 5 if the shares were effectively sold prior to the effective date.”




By returning this Questionnaire, the undersigned will be deemed to be aware of the foregoing interpretation.




I confirm that, to the best of my knowledge and belief, the foregoing statements (including without limitation the answers to this Questionnaire) are correct.




IN WITNESS WHEREOF the undersigned, by authority duly given, has caused this Questionnaire to be executed and delivered either in person or by its duly authorized agent.




Dated: ______________________________________
Beneficial Owner: ______________________________________By:Name:Title:


B-5