Amendment No. 1 To Product Development And Commercialization Agreement

Exhibit 10.12

CERTAIN MATERIAL (INDICATED BY AN ASTERISK) HAS BEEN OMITTED FROM THIS DOCUMENT PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT. THE OMITTED MATERIAL HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION. AMENDMENT NO. 1

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PRODUCT DEVELOPMENT AND

COMMERCIALIZATION AGREEMENT

This Amendment No. 1 (" Amendment" ) to that certain PRODUCT DEVELOPMENT AND COMMERCIALIZATION AGREEMENT (the " Agreement" ) entered into and made effective as of the 22 nd day of August, 2006 by and between ChemoCentryx, Inc., a Delaware corporation having its principal place of business at 850 Maude Avenue, Mountain View, CA 94043 (" ChemoCentryx" ), and Glaxo Group Limited, a company existing under the laws of England and Wales, having its registered office at Glaxo Wellcome House, Berkeley Avenue, Greenford, Middlesex, UB6 0NN, England (referred to herein as " GSK" ), collectively, the " Parties" , is hereby entered into by the Parties with an Amendment effective date of September 30th, 2007 (the " Amendment Effective Date" ). All capitalized terms not expressly defined in this Amendment shall have the meanings given to them in the Agreement.

The Parties agree to amend and do hereby amend the Agreement as follows:

A. Amendments Pertaining to Addition of a Celiac CCR9 PoC Trial

1. The following new Section 1.135 is added to the Agreement:

1.135 " Celiac CCR9 PoC Trial" shall mean a Phase 2 Clinical Trial of a Collaboration Compound targeting CCR9 that is designed in accordance with Exhibit 1, which is attached hereto and is hereby incorporated by reference, as has been mutually agreed by the Parties for a Celiac Indication (as defined under Section 1.136). Exhibit 1 shall include, and incorporate by reference, the memorandum of understanding and protocol covering such Phase 2 Clinical Trial. 2. The following new Section 1.136 is added to the Agreement:

1.136 " Celiac Indication" means an autoimmune intestinal disorder typically triggered by a specific food component called gluten (which is found in all forms of wheat, rye, barley and other related grains).

3. Section 2.3.5 is hereby amended and restated in its entirety as follows (newly added text in bold and underlined): 2.3.5 Decision Making Regarding Indications . Notwithstanding Sections 2.3.4(a) and (b), with respect to each Development Candidate nominated by the JSC, and in the course of such nomination process, the Parties shall mutually determine which potential Indication(s) to pursue for such Development Candidate and the related set of Progressed

Collaboration Compounds, (other than CCX282 and CCX282 Back-up Compounds for which ChemoCentryx shall have the right to pursue in Crohn' s Disease, in asthma as reflected in the Asthma CCR9 PoC Trial and in the Celiac Indication as reflected in a Celiac CCR9 PoC Trial as provided for in this Agreement). Accordingly, no Indication shall be pursued by ChemoCentryx under this Agreement with respect to any such Development Candidate or Progressed Compound without the prior mutual agreement of both Parties, through the JSC. In determining which Indication to pursue, the JSC shall take into consideration the estimated costs and possible trial design of the PoC Trial for such Indication for such Development Candidate, in addition to the relevant scientific, medical, safety and commercial considerations. 4. Section 3.6.3 is hereby amended and restated in its entirety as follows (newly added text in bold and underlined): 3.6.3 Indications. At the time of the JSC decision regarding nomination of a potential Development Candidate targeting a given Collaboration Target, the Parties, through the JSC, shall mutually determine which potential Indication(s) to pursue for such proposed Development Candidate and the related set of Progressed Collaboration Compounds. Notwithstanding the foregoing, the Parties agree that ChemoCentryx shall have the right to pursue CCX282 and CCX282 Back-up Compounds for CCR9, in Crohn' s Disease, in asthma as reflected in the Asthma CCR9 PoC Trial and in the Celiac Indication as reflected in a Celiac CCR9 PoC Trial as provided for in this Agreement. In the event the JSC cannot agree on such Indications, it shall proceed as provided in Section 2.3.5.

5. Section 3.7.2 is hereby amended by adding the following new paragraph (e):

3.7.2 (e) Celiac CCR9 PoC Trial . ChemoCentryx shall also have the right, in its sole discretion, to conduct a Celiac CCR9 PoC Trial; provided, however, that GSK shall have the right to review and comment on the design of any Celiac CCR9 PoC Trial before it is finalized, and GSK must approve the final applicable PoC Criteria and the final study design and content of such Celiac CCR9 PoC Trial prior to initiation, such approval not to be unreasonably withheld. The Parties understand and acknowledge that it is possible that a Celiac CCR9 PoC Trial may be completed prior to the PROTECT-1 Trial or the Asthma CCR9 PoC Trial, and therefore GSK may first have the opportunity to exercise its Product Option with respect to CCX282 in accordance with Section 4.3.1(b) based upon data resulting from such Celiac CCR9 PoC Trial rather than from the PROTECT-1 Trial or the Asthma CCR9 PoC Trial. Regardless of whether GSK exercises its Product Option at such time for the Celiac CCR9 PoC Trial or at a different time under Section 4.3.1(b), ChemoCentryx will continue the PROTECT-1 Trial unless terminated for good scientific, safety or ethical reasons.

6. Section 3.8.1 is hereby amended and restated in its entirety as follows (newly added text in bold and underlined):

3.8.1 For CCX282. Unless and until GSK exercises its Product Option with respect to CCX282 or a CCX282 Back-up Compound , promptly after the conduct of each of the following (a) the PROTECT-1 Induction Phase, (b) the PROTECT-1 Maintenance Phase,


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(c) a Celiac CCR9 PoC Trial, and (d) the Asthma CCR9 PoC Trial, as applicable, if ChemoCentryx determines that CCX282 or the CCX282 Back-up Compound meets the PoC Criteria therefor, ChemoCentryx shall promptly notify GSK, in writing, of such event. The JSC will, at a special ad hoc meeting to be scheduled, confirm that CCX282 or the CCX282 Back-up Compound meets such PoC Criteria and that the PoC Trial has successfully met the relevant endpoints. Following such confirmation, GSK shall have the right to exercise its Product Option with respect to CCX282 or the CCX282 Back-up Compound in accordance with Section 4.3.1(b) and Article 4. Where GSK does not so elect to exercise its Product Option at the time point referenced in clause (a) above, as provided in Section 4.3, then following the time point referenced in clause (b), (c), or (d) above, if ChemoCentryx again determines that CCX282 or a CCX282 Back-up Compound meets the PoC Criteria, ChemoCentryx shall promptly notify GSK, in writing, of such event. The JSC will, at a special ad hoc meeting to be scheduled, confirm that CCX282 or a CCX282 Back-up Compound meets such PoC Criteria. Following such confirmation, GSK shall again have the right to exercise its Product Option with respect to CCX282 or the CCX282 Back-up Compound in accordance with Article 4 and Section 4.3.1(b). Such process shall again continue with respect to all four (4) time points described in clauses (a), (b), (c) and (d) above, as and to the extent ChemoCentryx conducts such PoC Trials in accordance with the provisions of this Agreement, and CCX282 or a CCX282 Back-up Compound meets the PoC Criteria with respect to the PoC Trial referenced therein . GSK shall thus have a total of up to four (4) opportunities to exercise its Product Option with respect to CCX282 or a CCX282 Back-up Compound in accordance with Section 4.3.1(b), and the failure by GSK to exercise any of such opportunities shall not count against GSK' s Product Options, unless and until all of such opportunities with respect to CCX282 or a CCX282 Back-up Compound arising hereunder are declined by GSK.

7. Section 4.2.2 is hereby amended and restated in its entirety as follows (newly added text in bold and underlined):

4.2.2 For CCX282 or a CCX282 Back-up Compound . Notwithstanding the foregoing Section 4.2.1, a new and different PoC Trial Report for CCX282 or a CCX282 Back-up Compound shall be delivered to GSK within sixty (60) days of the JSC having determined that CCX282 or a CCX282 Back-up Compound meets the PoC Criteria and has successfully met the endpoints for the PoC Trial in each of the following situations: (a) the PROTECT-1 Induction Phase, (b) the PROTECT-1 Maintenance Phase, (c) a Celiac CCR9 PoC Trial, and (d) the Asthma CCR9 PoC Trial, and each such PoC Trial Report shall include all the preclinical and clinical data showing that the clinical endpoints have been achieved demonstrating the successful outcome of the respective portion of the PROTECT-1 Trial or a Celiac CCR9 PoC Trial or the Asthma CCR9 PoC Trial, as the case may be.

8. Section 4.3.1(b) is hereby amended and restated in its entirety as follows (newly added text in bold and underlined):

4.3.1(b) For CCX282 or a CCX282 Back-up Compound , GSK shall have a total of four (4) potential opportunities to exercise its Product Option, as follows. The Product


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Option for CCX282 shall be exercisable by GSK, at its sole discretion, upon each of the following occasions: within ninety (90) days (as may be extended pursuant to Section 4.3.1(a) above) after ChemoCentryx provides to GSK a PoC Trial Report with the preclinical and clinical data showing that clinical endpoints have been successfully met demonstrating the successful outcome of (i) the PROTECT-1 Induction Phase, (ii) the PROTECT-1 Maintenance Phase, (iii) a Celiac CCR9 PoC Trial, if conducted, and (iv ) the Asthma CCR9 PoC Trial, if conducted, for CCX282. In the event that GSK declines such exercise on the first or on the first three of such four opportunities to exercise its Product Option for CCX282 or a CCX282 Back-up Compound , such election(s) to decline to exercise at such first three opportunities shall not count against any of GSK' s Product Options, and GSK shall still retain a fourth opportunity to exercise its Product Option, if and when a fourth opportunity is triggered as described above. The Parties understand and agree that such a third and/or fourth opportunity may never be available in the event that ChemoCentryx elects not ever to conduct the Asthma CCR9 PoC Trial and/or a Celiac CCR9 PoC Trial . In addition, for clarity, the Parties understand and agree that CCX282 and its two Back-up Compounds collectively constitute only one Option Compound under this Agreement and only one Product Option hereunder, regardless of the total number of times that GSK' s Product Option is triggered for such set of Progressed Compounds by completion of successful PoC Trials for CCX282 and/or any of its Back-up Compounds, and regardless of the number of different Indications, formulations, methods of delivery, prodrugs, esters, salts, crystalline polymorphs, hydrates or solvates thereof which are Developed hereunder for such Progressed Compounds, taken collectively. It being understood, however that ChemoCentryx shall have no obligation to pursue any such different Indications, formulations, and the like.

B. Amendments Pertaining to Co-Development and Co-Promotion Rights for the Celiac Indication and to ChemoCentryx' Change of Control

1. Section 5.2.1 is hereby amended and restated in its entirety as follows (newly added text in bold and underlined):

5.2.1 Generally. Following GSK' s exercise of its Product Option, but not later than twelve (12) months prior to the first expected NDA filing for such Product Candidate targeting CCR9, GSK shall provide to ChemoCentryx a detailed development plan and associated budget for the conduct of the Dossier Studies for such Licensed Product targeting CCR9 (the " Development Plan and Budget" ). ChemoCentryx shall have the right to review and comment upon such Development Plan and Budget, and shall have the option (the " Co-Development Option" ) within ninety (90) days following receipt of the final Development Plan and Budget to co-fund Dossier Studies for any or all of (i) the Regulatory Approval of Crohn' s Disease only (the " CD Development Option" ); (ii) the Regulatory Approval of Crohn' s Disease as well as ulcerative colitis (the " CD/UC Development Option" ); or (iii) the Regulatory Approval of the Celiac Indication (the " Celiac Development Option" ). In the event that GSK subsequently significantly amends the Development Plan and Budget to include for the first time the ulcerative colitis Indication or the Celiac Indication by the addition of new Clinical S tudies targeting the ulcerative colitis Indication or the Celiac Indication , GSK shall promptly


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notify ChemoCentryx of such amendment , and ChemoCentryx shall have an additional ninety (90) days within which to review and comment upon such amended Development Plan and Budget and exercise the CD/UC Development Option or the Celiac Development Option , at its discretion. Depending on its election, ChemoCentryx shall receive additional royalties as set forth in Section 6.6.5(a) or Section 6.6.5(b), as applicable. The royalty rate increases resulting from exercise of the Celiac Development Option will be the same as for exercise of the CD Development Option. For clarity, the Parties understand that ChemoCentryx' s Co-Development Option under this Agreement shall apply only to CCR9.

2. Section 5.2.2 is hereby amended and restated in its entirety as follows (newly added text in bold and underlined):

5.2.2 Reimbursement of GSK Costs. Upon exercise of the Co-Development Option, ChemoCentryx shall pay to GSK a one time cash payment equal to thirty-five percent (35%) of the GSK Incurred Costs for any of the Crohn' s Disease Dossier Studies, the Crohn' s Disease and Ulcerative Colitis Dossier Studies , or the Celiac Disease Dossier Studies , depending on whether ChemoCentryx exercised the CD Development Option, the CD/UC Development Option or the Celiac Development Option, respectively . In addition, following exercise of the Co-Development Option, ChemoCentryx shall reimburse, on a quarterly basis, in arrears, thirty-five percent (35%) of all applicable Dossier Study Costs with respect to such Licensed Product through and including approval of the NDA.

(a) In the event that the actual Dossier Study Costs are reasonably expected to exceed [***] percent ([***]%) of the estimated costs for such studies as set forth in the Development Plan and Budget, ChemoCentryx shall have the option to either continue to co-fund such additional Dossier Study Costs, or to elect, in writing, to withdraw from its co-development participation in such Licensed Product entirely, or with respect to the Indication at issue, as the case may be, in which case GSK shall refund all Dossier Study Costs and all GSK Incurred Costs then paid to GSK to date by ChemoCentryx (the " Repayment Amount" ) in four (4) quarterly payments over the course of the following twelve (12) months.

(b) In addition, in the event that ChemoCentryx is unable to make its ongoing co-funding payments due to lack of financial wherewithal, but not due to any negative clinical trial results or lack of progress or any Third Party commitment or any change in the competitive environment, then ChemoCentryx shall have the right to elect, upon written notice to GSK, to withdraw from its co-development participation in such Product Candidate entirely, in which case GSK shall refund to ChemoCentryx the Repayment Amount, in the form of a royalty on U.S. Net Sales, as follows. In the event that ChemoCentryx is more than one hundred and twenty (120) days late on any co-funding payment due hereunder, GSK shall have the right to terminate ChemoCentryx' s right to participate in the Co-Development by default). GSK sh ...