Licenseand Development Agreement dated as of April 16, 2008 between Celldex Therapeutics, Inc. and Pfizer Vaccines LLC

consent of the other party, except as expressly permitted in this Agreement.  Neither Celldex nor its Affiliates shall disclose to any Third Party under any circumstance (A) any Celldex Confidential Information relating to any Compound, Licensed Product or Diagnostic Assay or (B) any data or results from any clinical study, the subject of which is a Licensed Product or Diagnostic Assay, without the prior written consent of Pfizer, except as expressly permitted in this Agreement.

(c)           Notwithstanding anything to the contrary in this Section 8, Pfizer may disclose Celldex Confidential Information to Third Parties as follows, provided that in each case Pfizer shall obtain the same confidentiality obligations from such Third Parties, or otherwise seek confidential treatment of such Celldex Confidential Information, to the extent available, as it obtains or seeks with respect to its own similar types of confidential information: (i) to Governmental Authorities (A) to the extent reasonably necessary or useful to obtain or maintain INDs or Regulatory Approvals for any Compound, Licensed Product or Diagnostic Assay within the Territory and (B) in order to respond to inquiries, requests or investigations of Governmental Authorities relating to this Agreement; (ii) to outside consultants, contractors, advisory boards, managed care organizations and non-clinical and clinical investigators, in each case to the extent reasonably necessary or useful to develop, register or market any Compound, Licensed Product or Diagnostic Assay as provided for under this Agreement; (iii) in connection with filing or prosecuting patent rights or trademark rights as permitted by this Agreement; (iv) in connection with prosecuting or defending litigation as permitted by this Agreement; (v) in connection with or included in scientific presentations and publications relating to Compounds, Licensed Products or Diagnostic Assays, including abstracts, posters, journal articles and the like, and posting results of and other information about clinical trials to clincialtrials.gov or PhRMA websites, provided that Celldex will be given an opportunity to review and comment on any such disclosure of Celldex Confidential Information prior to such presentation or publication and Pfizer shall consider such comments in good faith and shall remove any Celldex Confidential Information from such presentation or publication if such Celldex Confidential Information is objected to by Celldex and is unrelated to a Compound, Licensed Product or Diagnostic Assay; and (vi) to the extent necessary or desirable in order to enforce its rights under this Agreement.

(d)           Notwithstanding anything to the contrary in this Section 8, Celldex may disclose Pfizer Confidential Information, and Celldex Confidential Information exclusively licensed to Pfizer hereunder, to Third Parties as follows, provided that in each case Celldex shall obtain the same confidentiality obligations from such Third Parties, or otherwise seek confidential treatment of such Pfizer Confidential Information and such Celldex Confidential Information, to the extent available, as it obtains or seeks with respect to its own similar types of confidential information: (i) to Governmental Authorities (A) to the extent reasonably necessary or useful to obtain or maintain INDs for any Compound or Licensed Product within the Territory consistent with Celldex’s obligations under the Development Plan and (B) in order to respond to inquiries, requests or investigations of Governmental Authorities relating to this Agreement; (ii) to outside consultants, contractors, advisory boards and non-clinical and clinical investigators, in each case to the extent reasonably necessary or useful to develop any Compound or Licensed Product consistent with Celldex’s obligations under the Development Plan;

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(iii) to the Third Party Licensors to the extent necessary to comply with Celldex’s obligations under the Third Party Licenses; and (iv) to the extent necessary or desirable in order to enforce its rights under this Agreement.

8.2.          Publication.  Celldex shall not, and shall cause its Affiliates and the employees, consultants, contractors, licensees and agents of Celldex and its Affiliates not to, publish or present any information with respect to any Compound, Licensed Product or Diagnostic Assay without Pfizer’s prior written consent (which may be withheld in its sole and final discretion), except as may be required by Law or legal proceedings.

8.3.          Publicity.  The public announcement of the execution of this Agreement is set forth on Exhibit D attached hereto and shall be promptly disseminated following the execution of this Agreement by both parties.

(a)           Except as set forth in Section 8.2, Celldex shall not make (and shall cause its Affiliates not to make) any public statement (written or oral), including in analyst meetings, concerning the terms of, or events related to, this Agreement or concerning any Compound, Licensed Product or Diagnostic Assay, except where such statement: (i) is required by Law or legal proceedings, (ii) is required to be contained in Celldex financial statements prepared in accordance with generally acceptable accounting principles in the United States, (iii) has been announced previously in accordance with this Section 8.3 or (iv) has been announced previously by Pfizer, so long as, in the case of (iii) or (iv), such public statement is consistent with such previously announced statement.  In the case of any public statement (written or oral) that is required by Law or legal proceedings, Celldex shall (and shall cause its Affiliates to) (x) use Commercially Reasonable Efforts to obtain confidential treatment of financial and trade secret information and (y) if reasonably practicable under the circumstances, give Pfizer sufficient advance notice of the text so that Pfizer will have the opportunity to comment upon the statement, and give due consideration to any such comments in the final statement.

(b)           Except as otherwise permitted pursuant to Section 8.2, Pfizer shall, if reasonably practicable under the circumstances, give Celldex sufficient advance notice of the text of any public statement so that Celldex will have the opportunity to comment upon such statement.  Pfizer shall give due consideration to any such comments.

(c)           Each party and its Affiliates shall retain all right, title and interest in and to its and their respective trademarks, trade names, corporate names and logos.  No right is granted by virtue of this Agreement to a party or its Affiliates to use the corporate name or any other trade name of the other party or its Affiliates in any publicity, press release or public announcement relating to this Agreement without the prior written consent of the other party.

8.4.          Filing, Registration or Notification of this Agreement.  If a party determines that it is required by Law, or any of its Affiliates is required by Law, to publicly file, register or notify this Agreement with a Governmental Authority, such party (or such party’s Affiliate, as the case may be) shall (a) initially file a redacted copy of this Agreement (the “Redacted Agreement”) in the form of Exhibit E attached hereto, (b) request, and use commercially

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reasonable efforts to obtain, confidential treatment of all terms redacted from this Agreement, as reflected in the Redacted Agreement, for a period of at least *, (c) permit the other party to review and approve such request for confidential treatment and any subsequent correspondence with respect thereto at least five (5) Business Days prior to its submission to such Governmental Authority, (d) promptly deliver to the other party any written correspondence received by it or its representatives from such Governmental Authority with respect to such confidential treatment request and promptly advise the other party of any other communications between it or its representatives with such Governmental Authority with respect to such confidential treatment request, (e) upon the written request of the other party, request an appropriate extension of the term of the confidential treatment period and (f) if such Governmental Authority requests any changes to the redactions set forth in the Redacted Agreement, use commercially reasonable efforts to support the redactions in the Redacted Agreement as originally filed and shall not agree to any changes to the Redacted Agreement without first discussing such changes with the other party and taking the other party’s comments into consideration when deciding whether to agree to such changes.  Each party shall be responsible for its own legal and other external costs in connection with any such filing, registration or notification.

Section 9.              REPRESENTATIONS AND WARRANTIES.

9.1.          Celldex Representations and Warranties.  As of the date hereof and as of the Effective Date of this Agreement, Celldex hereby represents and warrants to Pfizer as follows:

(a)           Celldex has the corporate power and authority to execute and deliver this Agreement and to perform its obligations hereunder, and the execution, delivery and performance of this Agreement by Celldex have been duly and validly authorized and approved by proper corporate action on the part of Celldex, and Celldex has taken all other action required by Law, its certificate of incorporation, by-laws or other organizational documents or any agreement to which it is a party or to which it may be subject, required to authorize such execution, delivery and performance (other than compliance with all applicable requirements of the HSR Act).  Assuming due authorization, execution and delivery on the part of Pfizer, this Agreement constitutes a legal, valid and binding obligation of Celldex, enforceable against Celldex in accordance with its terms.

(b)           The execution and delivery of this Agreement by Celldex and the performance by Celldex contemplated hereunder does not and will not violate any Laws, except for such violations that would not have an adverse effect on the ability of Celldex to performs its obligations under this Agreement, or any order of any court or Governmental Authority.

(c)           To the Knowledge of Celldex, (i) the patents encompassed within the Celldex Patent Rights are valid and enforceable patents and (ii) the patent applications encompassed within the Celldex Patent Rights will be, if and when issued, valid and enforceable patents.  To the Knowledge of Celldex, no Third Party (i) is infringing any such patents or has misappropriated any Celldex Technology or (ii) except as set forth on Schedule 9.1(c), has challenged the ownership, scope, duration, validity, enforceability, priority or right to use of such patents (including by way of example through the

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institution or written threat of institution of interference, reexamination, protest, opposition, nullity or similar invalidity proceedings before the United States Patent and Trademark Office or any analogous foreign entity) or any Celldex Technology.

(d)           To the Knowledge of Celldex, the research, development, manufacture, use, sale, offer for sale, supply or importation by Celldex or Pfizer (or their respective Affiliates) of CDX-110, any Licensed Products containing CDX-110 (as such Licensed Products are currently constituted) and any * Diagnostic Assays (as such Diagnostic Assays are currently constituted), but not including *, does not and will not infringe any valid issued patent of any Third Party and does not and will not misappropriate any technology of any Third Party.  Prior to the Effective Date, neither Celldex nor any of its Affiliates has conducted any research, development, manufacturing, use, or sale of any Compound other than CDX-110 nor of any Licensed Product other than Licensed Products containing CDX-110.  Celldex has disclosed to Pfizer all Third Party patents and patent applications identified by counsel to Celldex in any freedom to operate or patentability searches or opinions, or otherwise made known to Celldex, relating to CDX-110 and Licensed Products containing CDX-110.  Celldex has received no written notice from a Third Party regarding, nor has any Knowledge that any Third Party intends to assert, any claim that the manufacture, use or sale of CDX-110 or the practice of the Celldex Patent Rights or use of the Celldex Technology infringes the intellectual property rights of a Third Party.

(e)           There is no legal claim, judgment or settlement against or owed by Celldex, or any order, writ, injunction or decree of any Governmental Authority against Celldex, in each case relating to CDX-110, any Licensed Product, the Celldex Patent Rights, the Celldex Technology or the transactions contemplated by this Agreement.

(f)            Subject to the provisions of the Third Party Licenses, Celldex’s right, title  and interest to all the Celldex Patent Rights and Celldex Technology are free of any lien, encumbrance, charge, security interest, mortgage or other similar restriction.  To the Knowledge of Celldex, the Third Party Licensors’ right, title and interest to the Celldex Controlled Patent Rights are free of any lien, encumbrance, charge, security interest, mortgage or other similar restriction (any such lien, encumbrance, charge, security interest, mortgage or other similar restriction, a “Third Party Licensor Lien”).  Subject to the provisions of the Third Party Licenses and any Third Party Licensor Liens, no person, firm, corporation or other entity (including any Affiliate of Celldex) has any right, interest or claim in or to, and neither Celldex nor any of its Affiliates has entered into any agreement granting any right, interest or claim in or to, any Celldex Patent Rights or Celldex Technology to any Third Party (including any academic organization or agency).  Without limiting the generality of the foregoing: (i) no Celldex Research Arrangement has been funded in whole or in part by any Third Party; (ii) each Celldex Research Arrangement is covered by a written agreement between Celldex and the Third Party(ies) involved in such Celldex Research Arrangement; (iii) Celldex exclusively owns all data and other intellectual property generated in the course of performance of each Celldex Research Arrangement conducted prior to the date hereof or the Effective Date, as the case may be; and (iv) all agreements with Third Parties relating to any Celldex Research Arrangement that is being conducted as of the date hereof or the Effective Date, as the

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case may be, provide that Celldex shall have exclusive ownership of all data and other intellectual property generated in the course of performance of such Celldex Research Arrangement.  For purposes of this Section 9.1, “Celldex Research Arrangement” means (x) any clinical trial or other research or development activities involving CDX-110 or any other Compound, Licensed Product or Diagnostic Assay performed by Celldex, any Affiliate of Celldex or any Third Party acting on Celldex’s behalf or under an agreement with Celldex or any Affiliate of Celldex or of which Celldex is otherwise aware, and (y) any research or development activities involving CDX-110 or any other Compound or Licensed Product performed by any Third Party to whom Celldex has provided CDX-110 or any such other Compound or Licensed Product at any time.  Schedule 9.1(f) lists every agreement relating to the Celldex Research Arrangements.

(g)           Prior to the Effective Date, the Compounds and Licensed Products have been developed, manufactured, stored, labeled, distributed and tested by Celldex and its Affiliates and, to Celldex’s Knowledge, by any Third Parties acting on behalf of Celldex, in compliance in all material respects with all applicable Laws.

(h)           The Patent Rights listed in Exhibit A are licensed to Celldex under the Third Party Licenses and are included in the Celldex Patent Rights licensed to Pfizer under this Agreement.  Other than the Patent Rights licensed to Celldex under the Third Party Licenses, Celldex does not own or control any Patent Rights relating to the Compounds, Licensed Products or Diagnostic Assays.  Since September 30, 2007, Celldex has not assigned or otherwise transferred ownership or control of any Patent Rights or Technology to Avant or any other Affiliate of Celldex.

(i)            Except for the Third Party Licenses, *, the * Supply Agreement and the agreements set forth in Schedule 9.1(f) (collectively, the “Third Party Agreements”), correct and complete copies of each of which have heretofore been delivered by Celldex to Pfizer, there are no licenses or other agreements, whether written or oral, to which Celldex or any of its Affiliates is a party that relate to the Compounds, Licensed Products or Diagnostic Assays or any patents or patent applications relating thereto.  The Third Party Agreements delivered by Celldex to Pfizer were true, accurate and complete copies of such agreements on the date of delivery and have not been modified, supplemented or amended since the date of delivery.  Each of the Third Party Agreements is in full force and effect.  Celldex is not in breach of any Third Party Agreement, and, to Celldex’s Knowledge, no other party to any Third Party Agreement is in breach thereof.  No party to any Third Party Agreement has notified in writing any other party thereto of any material breach thereof.  * has executed and delivered to Celldex the consent to assignment of the * Supply Agreement in the form attached hereto as Exhibit F, and Celldex has received no written notice from * revoking or purporting to revoke such consent.

(j)            Celldex has heretofore disclosed to Pfizer all material scientific and technical information and all information relating to safety and efficacy known to it or its Affiliates with respect to CDX-110, Licensed Products containing CDX-110 and * Diagnostic Assays.

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(k)           Celldex has heretofore disclosed to Pfizer all material correspondence and contact information between Celldex and the FDA and any other Governmental Authorities regarding CDX-110 or any Licensed Product containing CDX-110.

(l)            Except for filings pursuant to the HSR Act, if any, neither the execution and delivery of this Agreement nor the performance hereof by Celldex requires Celldex to obtain any permits, authorizations or consents from any Governmental Authority or from any other person, firm or corporation, and such execution, delivery and performance will not result in the breach of or give rise to any right of termination, rescission, renegotiation or acceleration under, or trigger any other rights under, any agreement or contract to which Celldex is a party or to which it may be subject that relates to the Celldex Patent Rights, the Celldex Technology, the Compounds or the Licensed Products.

(m)          There is (1) no Action pending against Celldex, any of its Affiliates or, to the Knowledge of Celldex, any Third Party, and (2) to the Knowledge of Celldex, no Action threatened and no Investigation pending or threatened against Celldex, any of its Affiliates or any Third Party, in each case in connection with the Celldex Patent Rights, the Celldex Technology, the Compounds or the Licensed Products or relating to the transactions contemplated by this Agreement.  For purposes of this Section 9.1(m): “Action” means any action, claim, demand, suit, proceeding, arbitration, grievance, citation, summons or subpoena of any nature, civil, criminal, regulatory or otherwise, in law or in equity; and “Investigation” means any inquiry or investigation of any nature, civil, criminal, regulatory or otherwise, in law or in equity.

Within five (5) Business Days following the Effective Date, Celldex shall deliver to Pfizer a certificate of Celldex, signed by an executive officer of Celldex, certifying that the representations and warranties of Celldex contained in this Section 9.1 were true and correct as of the Effective Date.

9.2.          Pfizer Representations and Warranties.  As of the date hereof and as of the Effective Date of this Agreement, Pfizer hereby represents and warrants to Celldex as follows:

(a)           Pfizer has the limited liability company power and authority to execute and deliver this Agreement and to perform its obligations hereunder, and the execution, delivery and performance of this Agreement by Pfizer have been duly and validly authorized and approved by proper limited liability company action on the part of Pfizer, and Pfizer has taken all other action required by Law, its certificate of formation and operating agreement, or any agreement to which it is a party or to which it may be subject, required to authorize such execution, delivery and performance.  Assuming due authorization, execution and delivery on the part of Celldex, this Agreement constitutes a legal, valid and binding obligation of Pfizer, enforceable against Pfizer in accordance with its terms.

(b)           The execution and delivery of this Agreement by Pfizer and the performance by Pfizer contemplated hereunder does not and will not violate any Laws, except for such violations that would not have an adverse effect on the ability of Pfizer to

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perform its obligations under this Agreement, or any order of any court or Governmental Authority.

(c)           Except for filings pursuant to the HSR Act, if any, neither the execution and delivery of this Agreement nor the performance hereof by Pfizer requires Pfizer to obtain any permits, authorizations or consents from any Governmental Authority (other than any regulatory approvals relating to the manufacture, use, importation or sale of any Compound or Licensed Product) or from any other person, firm or corporation, and such execution, delivery and performance will not result in the breach of or give rise to any right of termination under any agreement or contract to which Pfizer is a party or to which it may be subject, except for those breaches or rights that would not adversely affect the ability of Pfizer to perform its obligations under this Agreement.

(d)           There is no action, claim, demand, suit, proceeding, arbitration, grievance, citation, summons, subpoena, inquiry or investigation of any nature, civil, criminal, regulatory or otherwise, in law or in equity, pending or, to the Knowledge of Pfizer, threatened against Pfizer or any of its Affiliates relating to the transactions contemplated by this Agreement.

Within five (5) Business Days following the Effective Date, Pfizer shall deliver to Celldex a certificate of Pfizer, signed by an authorized officer of Pfizer, certifying that the representations and warranties of Pfizer contained in this Section 9.2 were true and correct as of the Effective Date.

9.3.          Disclaimer of Warranty.  EXCEPT AS OTHERWISE EXPRESSLY STATED IN THIS AGREEMENT, NEITHER PARTY MAKES ANY REPRESENTATION OR WARRANTY OF ANY KIND WITH RESPECT TO COMPOUNDS, LICENSED PRODUCTS, DIAGNOSTIC ASSAYS, PATENT RIGHTS, OR TECHNOLOGY.  EXCEPT AS OTHERWISE PROVIDED IN THIS SECTION 9, EACH PARTY EXPRESSLY DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.

9.4.          No Debarment.  In conducting any development activities under this Agreement, each party shall ensure that its Affiliates, employees, agents and contractors: (i) comply with all applicable Laws and all statutory and regulatory requirements of the FDA and any other Governmental Authority; and (ii) not utilize, in conducting studies on any Compound, Licensed Product or Diagnostic Assay, any person or entity that at such time is debarred by the FDA or under investigation by the FDA for debarment action pursuant to the provisions of the United States federal Generic Drug Enforcement Act of 1992.  Each party agrees to inform the other party in writing immediately if it or any person or entity who is performing services hereunder is so debarred or is the subject of a conviction described in Section 306 of the FDCA, or if any action, suit, claim, investigation or legal or administrative proceeding is pending or, to such party’s Knowledge, is threatened, relating to the debarment or conviction of such party or any person or entity used in any capacity by such party or any of its Affiliates in connection with the development of any Compound, Licensed Product or Diagnostic Assay.

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Section 10.            ADDITIONAL COVENANTS.

10.1.        Restrictions on Transfers and Liens.  Celldex shall not license, sell, assign or otherwise transfer to any person (including any Affiliate of Celldex) any Celldex Patent Rights or any Celldex Technology, or assign or otherwise transfer any of the Third Party Licenses or * or any of its rights or obligations thereunder to any person (including any Affiliate of Celldex) (or agree to do any of the foregoing) except to the extent permitted by, and in compliance with, Section 15.8.  In addition, Celldex hereby covenants and agrees that Celldex shall not incur or permit to exist (and shall cause each of its Affiliates not to incur or permit to exist), with respect to any Celldex Patent Rights and/or Celldex Technology, any lien, encumbrance, charge, security interest, mortgage, liability, grant of license to Third Parties or other restriction (including in connection with any indebtedness).

10.2.        Third Party Licenses.  Celldex (a) shall not execute or otherwise permit, and shall cause its Affiliates to refrain from executing or otherwise permitting, any amendment, modification or waiver to any of the Third Party Licenses, * or the * Supply Agreement without the prior written consent of Pfizer, (b) shall not make any election or exercise any right or option (or omit to take any action) which would, and shall cause its Affiliates to refrain from making any election or exercising any right or option (or omitting to take any action) which would, terminate or relinquish in whole or in part any right under a Third Party License, * or the * Supply Agreement, (c) shall comply, and shall cause its Affiliates to comply in all respects, with all of its, and its Affiliates’, obligations under the Third Party Licenses, * and the * Supply Agreement, (d) shall take, and shall cause its Affiliates to take, such actions as shall be necessary to keep in full force and effect the Third Party Licenses, * and the * Supply Agreement, and (e) shall give prompt notice to Pfizer, together with a detailed summary of outstanding issues if Pfizer so requests, of any notice received from the Third Party of any actual or alleged defaults, breaches, violations, proposed amendments or proposed modifications of, or any proposed waivers under, any of the Third Party Licenses, * or the * Supply Agreement by any of the parties thereto.

10.3.        Compliance with Laws.  Each of Celldex and Pfizer shall conduct, and shall use reasonable efforts to cause its Affiliates to conduct, all its activities contemplated under this Agreement in accordance with all applicable Laws of the country in which such activities are conducted.

10.4.        Conduct of Business.  From and after the date hereof and until the Effective Date, except as Pfizer shall otherwise consent to in writing, Celldex shall (a) operate the business of Celldex with respect to Compounds, Licensed Products, Diagnostic Assays, Celldex Patent Rights and Celldex Technology in the ordinary course consistent with past practice and (b) use Commercially Reasonable Efforts to preserve intact and keep in full force and effect all Celldex Patent Rights and Celldex Technology, and all related relationships with customers, suppliers, distributors, licensors, licensees and other Third Parties, and to keep available the services of its current employees who are involved in the research, development or commercialization of Compounds, Licensed Products or Diagnostic Assays (as the case may be).

10.5.        Access to Information.  From and after the date hereof, Celldex shall, upon reasonable notice from Pfizer, provide Pfizer and its agents and representatives with reasonable

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access, at Celldex’s place of business, during regular business hours, to (a) all information concerning Compounds, Licensed Products, Diagnostic Assays, Celldex Patent Rights and/or Celldex Technology and (b) all employees of Celldex who possess any information described in clause (a) of this Section 10.5.

Section 11.            TERM.

11.1.        Term.  Subject to Section 11.2, this Agreement shall be effective as of the Effective Date and shall, unless earlier terminated in accordance with Section 12, remain in effect until the expiration of the last-to-expire Royalty Term.  Simultaneously with the execution of this Agreement, the parties shall enter into the Assignment and Assumption Agreement relating to the * Supply Agreement in the form attached hereto as Exhibit G.

11.2.        Prior to Effective Date.  Prior to the Effective Date, neither Celldex nor Pfizer shall have any rights or obligations hereunder.  Notwithstanding anything to the contrary in Section 11.1, effective as of the date hereof, each of Pfizer and Celldex covenant and agree that Section 8, 10.1, 10.2, 10.4, 10.5, 11.2, 12.1(c), Section 14, 15.8 and 15.13 shall be in full force and effect unless this Agreement is terminated pursuant to Section 12 (including any applicable defined terms contained in such provisions).

Section 12.            TERMINATION.

12.1.        Termination Rights.  This Agreement may be terminated as follows:

(a)           If either Pfizer or Celldex materially breaches or materially defaults in the performance or observance of any of its respective obligations under this Agreement, and such breach or default is not cured within * after the giving of written notice by the other party specifying such breach or default, then such other party shall have the right to terminate this Agreement by providing the breaching party written notice within * following the expiration of such * period (such termination to be effective upon receipt of such termination notice).  For the purpose of this Section 12.1(a), a material breach or material default shall include a material inaccuracy in any warranty or representation contained herein.

(b)           At any time and for any reason, Pfizer, upon * written notice to Celldex, shall have the right, at Pfizer’s sole discretion, to terminate this Agreement, such termination to be effective upon the expiration of such * period.  In order to ensure the smooth transition of the development and/or commercialization of any Compound or Licensed Product from Pfizer to Celldex or a Third Party designated by Celldex, promptly after receipt by Celldex of such written notice, representatives of Pfizer and Celldex will meet to negotiate in good faith the terms of a transition plan with respect to all then-current as well as planned activities relating to Compounds and Licensed Products.

(c)           Either party shall have the right to terminate this Agreement if the Effective Date has not occurred (for any reason) by *.

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(d)           If Pfizer, its Affiliate or sublicensee commences any legal proceeding that challenges the validity, enforceability or ownership of any Celldex Patent Right set forth on Exhibit A, Celldex shall have the right to immediately terminate the license granted to Pfizer by Celldex pursuant to Section 3.1(a) under the challenged patent by giving notice to Pfizer.  The foregoing right of Celldex to terminate Pfizer’s license under a challenged patent shall not apply to any such challenge that arises out of or is in connection with any legal action or counterclaim commenced by Celldex against Pfizer, whether arising out of or in connection with this Agreement or otherwise.

12.2.        Accrued Obligations.  Expiration or termination of this Agreement for any reason (a) shall be without prejudice to Celldex’s right to receive all royalties accrued under Section 5.6 prior to the effective date of such termination and to any other remedies that either party may otherwise have and (b) shall not release a party hereto from any indebtedness, liability or other obligation incurred hereunder by such party prior to the date of termination or expiration.

12.3.        Effect of Termination.

(a)           Upon any termination of this Agreement pursuant to Section 12.1, all licenses and rights granted herein to Pfizer shall terminate, other than the license granted to Pfizer in Section 3.3(a) (Non-Exclusive Research License) and except as otherwise provided in this Section 12.3.

(b)           If Pfizer terminates this Agreement under Section 12.1(b) other than for reasons related to the safety of any Compound or Licensed Product (as determined in good faith by Pfizer, taking into account the indication(s) for which the Compound or Licensed Product was being developed or commercialized) or Celldex terminates this Agreement under Section 12.1(a) or 12.1(d), Pfizer shall, promptly after such termination: (i) transfer to Celldex ownership of all regulatory filings and Regulatory Approvals that relate solely to Licensed Products; and (ii) deliver or make available to Celldex, in the same form in which Pfizer maintains such items, copies of those material reports, records and regulatory correspondence in Pfizer’s possession or control that (A) relate solely to the pre-clinical and clinical development under this Agreement of Compounds or Licensed Products and (B) are necessary for Celldex to obtain Regulatory Approval for Licensed Products; provided that the parties agree that any failure by Pfizer to provide such reports, records or correspondence to Celldex despite Pfizer’s Commercially Reasonable Efforts to do so shall not be a breach of Pfizer’s obligations under this Section 12.3.

(c)           If (i) Pfizer terminates this Agreement under Section 12.1(b), or Celldex terminates this Agreement under Section 12.1(a) or 12.1(d), after * and (ii) Celldex subsequently commercializes such Licensed Product, Celldex will pay to Pfizer royalties in the amount of * of the annual net sales of such Licensed Product by Celldex, its Affiliates and licensees and sublicensees (where “net sales” of Celldex, its Affiliates and licensees and sublicensees is calculated in substantially the same manner as Net Sales are calculated under this Agreement).  Such royalties will be payable on a country-by-country basis during the Royalty Term that otherwise would have applied if this Agreement had not been terminated.

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(d)           If Pfizer terminates this Agreement under Section 12.1(b), or Celldex terminates this Agreement under Section 12.1(a) or 12.1(d), Celldex shall have the following rights, and Pfizer shall have the following obligations:

(i)            Celldex will, from the effective date of any such termination, have a non-exclusive, perpetual, irrevocable, worldwide, royalty-free (subject to Section 12.3(c)) license, with the right to sublicense, under the Pfizer Applied Technology, Pfizer Patent Rights and any Joint Patent Rights not previously assigned to Celldex that are necessary to research, develop, make, have made, use, sell, offer for sale, supply, cause to be supplied and import any Licensed Product that is in active clinical development or has been commercialized at the time of termination (a “Reverted Product”), solely to research, develop, make, have made, use, sell, offer for sale, supply, cause to be supplied and import such Reverted Product; provided that, if any of such Pfizer Applied Technology or Pfizer Patent Rights is licensed by Pfizer or any of its Affiliates from a Third Party, (A) Celldex’s license rights under this Section 12.3(d) shall be limited to the extent required under any agreement with such Third Party and (B) Celldex shall pay to Pfizer the amount of any Third Party royalties payable by Pfizer relating to such Pfizer Applied Technology or Pfizer Patent Rights (as the case maybe) in respect of such Reverted Product.

(ii)           Pfizer shall have the first right, but not the obligation, to continue prosecution and maintenance at its own expense of all Pfizer Patent Rights and all Joint Patent Rights not previously assigned to Celldex that are licensed to Celldex under Section 12.3(d)(i) (the “Reverted Product Patent Rights”).  Within sixty (60) days of termination of this Agreement, Celldex shall give notice to Pfizer specifying which Pfizer Patent Rights and Joint Patent Rights it believes are Reverted Product Patent Rights.  No later than sixty (60) days prior to the applicable Paris Convention date or PCT nationalization date, as the case may be, for a given Reverted Product Patent Right, Pfizer shall provide Celldex with a list of the countries in which Pfizer has decided to extend such Reverted Product Patent Right.  If Pfizer has decided not to continue the prosecution or maintenance of a patent application or patent that is a Reverted Product Patent Right, then Celldex shall have the option to obtain ownership of such patent applications and patents * and to continue the prosecution of such patent applications and the maintenance of such patents in such country, at its own cost and expense, in Celldex’s name (except in the case of a United States patent or patent application that is tied by a terminal disclaimer to another Patent Right owned by Pfizer).  If Celldex exercises such option to obtain ownership of such Reverted Product Patent Rights, Celldex shall, and shall cause its Affiliates to, grant to Pfizer a non-exclusive, irrevocable, worldwide, royalty-free, perpetual license, with the right to sublicense, under such Reverted Product Patent Rights for all uses.  Notwithstanding the provisions of Section 15.8, but subject to all rights granted herein to Celldex, Pfizer may transfer any Reverted Product Patent Right to a Third Party without Celldex’s consent; provided, however, that Pfizer shall ensure that any such Third Party transferee agrees in writing to comply with the obligations set forth in this Section 12.3(d)(ii) relating to such Reverted Product Patent Right.

(iii)          Celldex shall have the right to submit a written notice to Pfizer within * of termination requesting that Pfizer enter good faith negotiations for *.  If Pfizer

46

consents in writing to such negotiations, which consent may be withheld in Pfizer’s sole discretion, the parties shall negotiate in good faith the terms of such license for up to *.  In the event the parties do not agree on the terms of such a license before the end of such * negotiation period, Pfizer shall have no further obligation under this Section 12.3(d)(iii).

(iv)          Pfizer will assign to Celldex Pfizer’s rights, title and interest under the * Supply Agreement, as amended from time to time and then in effect, in whole or in part (at Pfizer’s option) to the extent necessary to enable Celldex to purchase * * (as defined in the * Supply Agreement) for the manufacturing of Compounds and Licensed Products.  Any such assignment will be subject to the terms of an assignment and assumption agreement between Celldex and Pfizer on terms that are substantially similar to the terms of the Assignment and Assumption Agreement between the parties dated as of the date hereof.

(e)           Following termination of this Agreement pursuant to Section 12.1: (i) each of Pfizer and Celldex shall, upon request of the other party, return or destroy all Celldex Confidential Information and Pfizer Confidential Information, respectively, disclosed to it pursuant to this Agreement, including all copies and extracts of documents, as promptly as practicable following receipt of such request, except that one (1) copy may be kept for the purpose of complying with continuing obligations under this Agreement.

(f)            If this Agreement is terminated by Pfizer pursuant to Section 12.1(a), the following provisions shall apply:

(i)            all licenses granted by each party to the other party under this Agreement shall terminate, other than the license granted to Pfizer in Section 3.3(a) (Non-Exclusive Research License); and

(ii)           subject to the provisions of Section 15.6, this Agreement shall be of no further force or effect.

12.4.        Bankruptcy.  All rights and licenses granted under or pursuant to this Agreement by Celldex are, and shall otherwise be deemed to be, for purposes of Section 365(n) of the U.S. Bankruptcy Code, licenses of rights to “intellectual property” as defined under Section 101 of the U.S. Bankruptcy Code.  The parties agree that Pfizer, as licensee of intellectual property under this Agreement, shall retain and may fully exercise all of its rights and elections under the U.S. Bankruptcy Code.  The parties further agree that, in the event of a rejection of this Agreement by Celldex in any bankruptcy proceeding by or against Celldex under the U.S. Bankruptcy Code, (a) Pfizer shall be entitled to a complete duplicate of (or complete access to, as appropriate) any such intellectual property and all embodiments of such intellectual property, which, if not already in Pfizer’s possession, shall be promptly delivered to it upon Pfizer’s written request therefor, and (b) Celldex shall not interfere with Pfizer’s rights to intellectual property and all embodiments of intellectual property, and shall assist and not interfere with Pfizer in obtaining intellectual property and all embodiments of intellectual property from another entity.  The term “embodiments” of intellectual property includes all tangible, intangible, electronic or other

47

embodiments of rights and licenses hereunder, including all compounds and products embodying intellectual property, Licensed Products, regulatory filings and related rights, and Technology.

Section 13.            INDEMNIFICATION.

13.1.        Indemnification.

(a)           Except as set forth on Schedule 13.1, Celldex will indemnify, defend and hold Pfizer and Pfizer’s Affiliates, and their respective directors, officers and employees (collectively, “Pfizer Indemnified Parties,” and each a “Pfizer Indemnified Party”), harmless from any and all Losses (as defined below) incurred by any of them as a result of:

(i)            the breach of any covenant, warranty or representation made by Celldex under this Agreement;

(ii)           the negligence, recklessness, or willful misconduct of Celldex or any of its Affiliates;

(iii)          any acts or omissions of Celldex or any of its Affiliates, agents, consultants, contractors or other Third Parties, in connection with the research, development or commercialization of Compounds, Licensed Products or Diagnostic Assays prior to or after the Effective Date or following termination in whole or in part of this Agreement and the reversion of the applicable rights hereunder to Celldex in accordance with Section 12.3; or

(iv)          any claim for death, bodily injury or property damage arising from the research, development, manufacture (for use, distribution, sale or commercialization by or on behalf of Celldex, its Affiliates or sublicensees, including Pfizer under this Agreement), use, distribution, sale or commercialization of any Compound, Licensed Product or Diagnostic Assay by Celldex, its Affiliates, sublicensees, employees or agents (other than a Pfizer Indemnified Party).

Celldex shall be obligated to so indemnify, defend and hold Pfizer harmless from such Losses only to the extent that such Losses do not arise from the negligence, recklessness or willful misconduct of any Pfizer Indemnified Party or the breach of any covenant, warranty or representation made by Pfizer under this Agreement.

(b)           Pfizer will indemnify, defend and hold Celldex and Celldex’s Affiliates, and their respective directors, officers and employees (collectively, “Celldex Indemnified Parties,” and each a “Celldex Indemnified Party”), harmless from any and all Losses incurred by any of them as a result of:

(i)            the breach of any covenant, warranty or representation made by Pfizer under this Agreement;

(ii)           the negligence, recklessness, or willful misconduct of Pfizer or any of its Affiliates;

48

(iii)          any acts or omissions of Pfizer or any of its Affiliates in connection with the research, development or commercialization of Compounds, Licensed Products or Diagnostic Assays during the Term; or

(iv)          any claim for death, bodily injury or property damage arising from the research, development, manufacture (for use, distribution, sale or commercialization by or on behalf of Pfizer, its Affiliates or sublicensees or use by or on behalf of Celldex under this Agreement), use, distribution, sale or commercialization of any Compound, Licensed Product or Diagnostic Assay by Pfizer, its Affiliates, sublicensees, employees or agents (other than a Celldex Indemnified Party).

In each case, Pfizer shall be obligated to so indemnify, defend and hold Celldex harmless from such Losses only to the extent that such Losses do not arise from the negligence, recklessness or willful misconduct of any Celldex Indemnified Party or the breach of any covenant, warranty or representation made by Celldex under this Agreement.

13.2.        Losses.  For purposes of this Agreement, “Losses” shall mean any and all costs, expenses, claims, losses, liabilities, damages, fines, royalties, governmental penalties or punitive damages, deficiencies, interest, settlement amounts, awards and judgments, including any and all reasonable, out-of-pocket costs and expenses properly incurred as a result of a claim, in each case solely to the extent such Loss is the result of a claim initiated by a Third Party (including reasonable, out-of-pocket attorneys’ fees and all other expenses reasonably incurred in investigating, preparing or defending any litigation or proceeding, commenced or threatened), and in each case, net of any tax benefit or insurance recovery received as a result of such Loss.

13.3.        Defense Procedures; Procedures for Third Party Claims.  In the event that any Third Party (in no event to include any Affiliate of any of the parties) asserts a claim with respect to any matter for which a party (the “Indemnified Party”) is entitled to indemnification hereunder (a “Third Party Claim”), then the Indemnified Party shall promptly notify the party obligated to indemnify the Indemnified Party (the “Indemnifying Party”) thereof; provided, however, that no delay on the part of the Indemnified Party in notifying the Indemnifying Party shall relieve the Indemnifying Party from any obligation hereunder unless (and then only to the extent that) the Indemnifying Party is prejudiced thereby.

(a)           Subject to Pfizer’s right to control the defense of actions described in Sections 7.8, 7.9, 7.10 and 7.11 (even where Celldex is the Indemnifying Party), the Indemnifying Party shall have the right, exercisable by notice to the Indemnified Party within ten (10) Business Days after receipt of notice from the Indemnified Party of the commencement of or assertion of any Third Party Claim, to assume direction and control of the defense, litigation, settlement, appeal or other disposition of the Third Party Claim (including the right to settle the claim solely for monetary consideration) with counsel selected by the Indemnifying Party and reasonably acceptable to the Indemnified Party; provided that (i) the Indemnifying Party has sufficient financial resources, in the reasonable judgment of the Indemnified Party, to satisfy the amount of any adverse monetary judgment that is sought, (ii) the Third Party Claim seeks solely monetary damages and (iii) the Indemnifying Party expressly agrees in writing that as between the Indemnifying Party and the Indemnified Party, the Indemnifying Party shall be solely

49

obligated to satisfy and discharge the Third Party Claim in full (the conditions set forth in clauses (i), (ii) and (iii) above are collectively referred to as the “Litigation Conditions”).

(b)           Within ten (10) Business Days after the Indemnifying Party has given notice to the Indemnified Party of its exercise of its right to defend a Third Party Claim, the Indemnified Party shall give notice to the Indemnifying Party of any objection thereto based upon the Litigation Conditions.  If the Indemnified Party reasonably so objects, the Indemnified Party shall continue to defend the Third Party Claim, at the expense of the Indemnifying Party, until such time as such objection is withdrawn.  If no such notice is given, or if any such objection is withdrawn, the Indemnifying Party shall be entitled, at its sole cost and expense, to assume direction and control of such defense, with counsel selected by the Indemnifying Party and reasonably acceptable to the Indemnified Party.  During such time as the Indemnifying Party is controlling the defense of such Third Party Claim, the Indemnified Party shall cooperate, and shall cause its Affiliates and agents to cooperate upon request of the Indemnifying Party, in the defense or prosecution of the Third Party Claim, including by furnishing such records, information and testimony and attending such conferences, discovery proceedings, hearings, trials or appeals as may reasonably be requested by the Indemnifying Party.  In the event that the Indemnifying Party does not satisfy the Litigation Conditions or does not notify the Indemnified Party of the Indemnifying Party’s intent to defend any Third Party Claim within ten (10) Business Days after notice thereof, the Indemnified Party may (without further notice to the Indemnifying Party) undertake the defense thereof with counsel of its choice and at the Indemnifying Party’s expense (including reasonable, out-of-pocket attorneys’ fees and costs and expenses of enforcement or defense).  The Indemnifying Party or the Indemnified Party, as the case may be, shall have the right to join in (including the right to conduct discovery, interview and examine witnesses and participate in all settlement conferences), but not control, at its own expense, the defense of any Third Party Claim that the other party is defending as provided in this Agreement.

(c)           The Indemnifying Party shall not, without the prior written consent of the Indemnified Party, enter into any compromise or settlement that commits the Indemnified Party to take, or to forbear to take, any action.  The Indemnified Party shall have the sole and exclusive right to settle any Third Party Claim, on such terms and conditions as it deems reasonably appropriate, to the extent such Third Party Claim involves equitable or other non-monetary relief, but shall not have the right to settle such Third Party Claim to the extent such Third Party Claim involves monetary damages without the prior written consent of the Indemnifying Party.  Each of the Indemnifying Party and the Indemnified Party shall not make any admission of liability in respect of any Third Party Claim without the prior written consent of the other party, and the Indemnified Party shall use reasonable efforts to mitigate Losses arising from the Third Party Claim.

13.4.        Disclaimer of Liability for Consequential Damages.  IN NO EVENT SHALL ANY PARTY OR ANY OF ITS AFFILIATES BE LIABLE UNDER THIS AGREEMENT FOR SPECIAL, INDIRECT, INCIDENTAL OR CONSEQUENTIAL DAMAGES, WHETHER IN CONTRACT, WARRANTY, TORT, NEGLIGENCE, STRICT LIABILITY OR OTHERWISE, INCLUDING LOSS OF PROFITS OR REVENUE,  SUFFERED BY PFIZER, CELLDEX OR ANY OF THEIR RESPECTIVE AFFILIATES, DIRECTORS, OFFICERS

50

AND EMPLOYEES, EXCEPT (A) TO THE EXTENT OF ANY SUCH DAMAGES PAID TO A THIRD PARTY IN CONNECTION WITH A THIRD PARTY CLAIM AND (B) FOR PURPOSES OF INDEMNIFICATION PURSUANT TO THIS SECTION 13, IN THE EVENT OF FRAUD; PROVIDED THAT THIS SECTION 13.4 SHALL NOT RELIEVE EITHER PARTY FROM ITS PAYMENT OBLIGATIONS UNDER THIS AGREEMENT.

13.5.        Sole Remedy.  EXCEPT AS EXPRESSLY PROVIDED IN THIS AGREEMENT AND EXCEPT FOR ANY EQUITABLE REMEDIES THAT MAY BE AVAILABLE TO A PARTY,  INDEMNIFICATION  PURSUANT TO THIS SECTION 13 SHALL BE THE SOLE AND EXCLUSIVE REMEDY (WHETHER BASED ON CONTRACT, TORT OR ANY OTHER LEGAL THEORY) AVAILABLE TO CELLDEX OR PFIZER FOR THE MATTERS COVERED THEREIN.

Section 14.            GOVERNING LAW AND JURISDICTION.

14.1.        Governing Law.  This Agreement shall be governed by and construed in accordance with the substantive laws of the State of New York, without regard to conflicts of law rules.

14.2.        Jurisdiction.  With the exception of those matters referred for resolution by independent accountants under Section 6.5, in the event of any controversy, claim or counterclaim arising out of or relating to this Agreement, the parties shall first attempt to resolve such controversy or claim through good faith negotiations for a period of not less than thirty (30) days following notification of such controversy or claim to the other party.  If such controversy or claim cannot be resolved by means of such negotiations during such period, then such controversy or claim shall be resolved by the United States District Court for the Southern District of New York or a local court sitting in New York, New York (collectively, the “Courts”).  Each party (a) irrevocably submits to the exclusive jurisdiction in the Courts for purposes of any action, suit or other proceeding relating to or arising out of this Agreement and (b) agrees not to raise any objection at any time to the laying or maintaining of the venue of any such action, suit or proceeding in any of the Courts, irrevocably waives any claim that such action, suit or other proceeding has been brought in an inconvenient forum and further irrevocably waives the right to object, with respect to such action, suit or other proceeding, that such Court does not have any jurisdiction over such party.  Celldex hereby irrevocably designates, appoints and empowers Corporation Service Company, 1133 Avenue of the Americas, New York, New York  10036-6710, as its true and lawful agent and attorney-in-fact in its name, place and stead to receive and accept on its behalf service of process in any action, suit or proceeding in the Courts with respect to any matters as to which it has submitted to jurisdiction as set forth in the immediately preceding sentence.

Section 15.            MISCELLANEOUS.

15.1.        Force Majeure.  Neither party hereto shall be liable to the other party for any losses or damages attributable to a default in or breach of this Agreement that is the result of war (whether declared or undeclared), acts of God, revolution, acts of terror, fire, earthquake, flood, pestilence, riot, enactment or change of Law (following the Effective Date), accident(s), labor trouble, or shortage of or inability to obtain material equipment or transport or any other cause

51

beyond the reasonable control of such party; provided that if such a cause occurs, then the party affected will promptly notify the other party of the nature and likely result and duration (if known) of such cause and use commercially reasonable efforts to reduce the effect.  If the event lasts for a period of longer than three (3) months, the parties shall meet and discuss appropriate remedial measures.

15.2.        Severability.  If and solely to the extent that any provision of this Agreement shall be invalid or unenforceable, or shall render this entire Agreement to be unenforceable or invalid, such offending provision shall be of no effect and shall not affect the validity of the remainder of this Agreement or any of its provisions; provided, however, the parties shall use their respective reasonable efforts to replace the invalid provisions in a manner that best accomplishes the original intentions of the parties.

15.3.        Waivers.  Any term or condition of this Agreement may be waived at any time by the party that is entitled to the benefit thereof, but no such waiver shall be effective unless set forth in a written instrument duly executed by or on behalf of the party or parties waiving such term or condition.  Neither the waiver by any party of any term or condition of this Agreement nor the failure on the part of any party, in one or more instances, to enforce any of the provisions of this Agreement or to exercise any right or privilege, shall be deemed or construed to be a waiver of such term or condition for any similar instance in the future or of any subsequent breach hereof.  All rights, remedies, undertakings, obligations and agreements contained in this Agreement shall be cumulative and none of them shall be a limitation of any other remedy, right, undertaking, obligation or agreement.

15.4.        Entire Agreement; Amendments.  This Agreement, together with the Stock Purchase Agreement, * and Assignment and Assumption Agreement relating to the * Supply Agreement, sets forth the entire agreement and understanding between the parties as to the subject matter hereof and supersedes all agreements or understandings, verbal or written, made between Celldex and Pfizer before the date hereof with respect to the subject matter hereof, including the Confidentiality Agreement between Celldex and Pfizer Inc., dated December 21, 2006, as amended on January 22, 2007.  All Celldex Confidential Information disclosed to Pfizer prior to the Effective Date will be deemed to have been disclosed pursuant to this Agreement.  None of the terms of this Agreement shall be amended, supplemented or modified except in writing signed by the parties.

15.5.        Pfizer’s Right of Setoff.  If Celldex materially breaches this Agreement and fails to cure such breach within the time periods provided under Section 12.1(a) and Pfizer does not elect to terminate this Agreement pursuant to Section 12.1(a), then, in addition to any other remedies Pfizer may have under this Agreement or otherwise, Pfizer may setoff against any amounts owed to Celldex pursuant to Section 5 the amount of any losses, damages and expenses incurred by Pfizer as a result of Celldex’s material breach of this Agreement (except to the extent such amounts have already been setoff pursuant to Section 5.8(c)).

15.6.        Pfizer *.

(a)           Notwithstanding anything to the contrary contained herein or in the *, Pfizer shall * results from a breach by Pfizer of its obligations under this Agreement,

52

which breach remains uncured * following receipt by Pfizer of a notice of breach pursuant to Section 12.1(a) hereof.

(b)           In the event Celldex believes that Pfizer has * in breach of the provisions of Section 15.6(a), Celldex may so notify Pfizer in writing.  If Pfizer does not object in writing to such alleged breach within * of receipt of such written notice, Pfizer shall promptly *.  In the event that Pfizer objects to such notice of breach within the time period specified, Celldex may pursue all legal and equitable remedies available to it in the Courts.  In the event that Pfizer is found by a final, nonappealable decision of a Court to have breached the provisions of Section 15.6(a) with respect to *, Pfizer shall promptly thereafter *.  Pfizer agrees that a breach of this Section 15.6(b) will cause irreparable harm to Celldex, and that any breach of this Section 15.6(b) by Pfizer will entitle Celldex to seek injunctive relief, in addition to any other legal remedies available to it, in any court of competent jurisdiction.

15.7.        Survival.  The provisions of Sections 3.3 (Non-Exclusive Research License), 3.6 (Celldex Retained Rights), 6.5 (Inspection of Records), 7.1 (Ownership of Inventions), 8.1 (Confidential Information), 12.3 (Effect of Termination), Section 13 (Indemnification) and Section 14 (Governing Law and Jurisdiction), as well as any other Sections or defined terms referred to in such Sections or necessary to give them effect shall survive termination or expiration of this Agreement and remain in force until discharged in full.  Furthermore, any other provisions required to interpret and enforce the parties’ rights and obligations or to wind up their outstanding obligations under this Agreement shall survive to the extent required.

15.8.        Assignment.

(a)           Neither this Agreement nor any rights or obligations of either party to this Agreement may be assigned or otherwise transferred by either party without the prior written consent of the other party; provided, however, either party may, without such consent, assign this Agreement, in whole or in part: (i) to any of its respective Affiliates, subject to Section 15.8(b) in the case of Celldex; provided that such assigning party shall remain jointly and severally liable with such Affiliate in respect of all obligations so assigned; (ii) to a Third Party where a party or its Affiliate is required, or makes a good faith determination based on advice of counsel, to divest any of the Licensed Products or Diagnostic Assays in order to comply with Law or the order of any Governmental Authority as a result of a merger or acquisition; (iii) to an entity that acquires all or substantially all of its assets, subject to Section 15.8(b) in the case of Celldex; or (iv) to the successor entity resulting from any merger or consolidation of such party with or into such entity (including a merger of Celldex with Avant into a single entity), subject to Section 15.8(b) in the case of Celldex.

(b)           Celldex shall not sell, assign or otherwise transfer Celldex Patent Rights, Celldex Technology, Third Party Licenses and/or * to any person (including any Affiliate of Celldex) except to (w) Avant (so long as Avant is the sole stockholder of Celldex), (x) a wholly-owned direct or indirect subsidiary of Celldex, (y) an acquiring entity in accordance with Section 15.8(a)(iii) or (z) a successor corporation or entity in accordance with Section 15.8(a)(iv), and solely in each case if (i) Avant, or such subsidiary,

53

corporation or entity (each, a “transferee”) is and continues to be at all times incorporated and domiciled (including with respect to principal headquarters of such transferee, but not with respect to any affiliate or parent entity of such transferee) in any state of the United States of America and (ii) prior to any such sale, assignment or transfer, such transferee has acknowledged and confirmed in writing to Pfizer, all in a manner reasonably acceptable to Pfizer, that, effective as of such sale, assignment or other transfer, such transferee shall be bound by this Agreement as if it were a party to it as and to the identical extent applicable to Celldex with respect to Celldex Patent Rights and/or Celldex Technology; provided, however, that Celldex shall not sell, assign or otherwise transfer any of the * to any person unless Celldex simultaneously sells, assigns or otherwise transfers the Third Party License and Celldex Patent Rights that are related to such * to the same person.

(c)           Any purported assignment in violation of this Section 15.8 shall be void.  Any permitted assignee shall assume all obligations of its assignor under this Agreement.

15.9.        Independent Contractor.  The relationship between Celldex and Pfizer is that of independent contractors.  Celldex and Pfizer are not joint venturers, partners, principal and agent, employer and employee, and have no other relationship other than independent contracting parties.

15.10.      Notices.  Each communication and document made or delivered by one party to another under this Agreement shall be made in the English language.  All notices, consents, approvals, requests or other communications required hereunder given by one party to the other hereunder shall be in writing and made by registered or certified air mail, facsimile, express overnight courier or delivered personally to the following addresses of the respective parties:

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Notices hereunder shall be deemed to be effective (a) upon receipt if personally delivered, (b) on the tenth (10th) Business Day following the date of mailing if sent by registered or certified air mail; (c) on the second (2nd) Business Day following the date of transmission or delivery to the overnight courier if sent by facsimile or overnight courier.  A party may change its address listed above by sending notice to the other party in accordance with this Section 15.10.

15.11.      Third Party Beneficiaries.  None of the provisions of this Agreement shall be for the benefit of or enforceable by any Third Party, including any creditor of either party.  No Third Party shall obtain any right under any provision of this Agreement or shall by reason of any such provision make any claim in respect of any debt, liability or obligation (or otherwise) against either party.

15.12.      Binding Effect.  This Agreement shall be binding upon and inure to the benefit of the parties hereto and their respective heirs, successors and permitted assigns.

15.13.      Performance by Affiliates.  To the extent that this Agreement imposes obligations on Affiliates of a party, such party agrees to cause its Affiliates to perform such obligations.  Pfizer may use one or more of its Affiliates to perform its obligations and duties hereunder, provided that Pfizer shall remain liable hereunder for the prompt payment and performance of all of its obligations hereunder.  Subject to Section 4.5(b), Celldex may use one or more of its Affiliates to perform its obligations and duties hereunder, provided that Celldex shall remain liable hereunder for the performance of all of its obligations hereunder.  Avant hereby agrees to cause Celldex to perform its obligations under this Agreement.

15.14.      Counterparts.  This Agreement may be executed in any two or more counterparts, each of which, when executed, shall be deemed to be an original and all of which together shall constitute one and the same document.

15.15.      Headings.  Headings in this Agreement are included herein for ease of reference only and shall have no legal effect.  References to the parties, Sections, Schedules and Exhibits are to the parties, Sections, Schedules and Exhibits to and of this Agreement unless otherwise specified.

[Remainder of Page Intentionally Left Blank]

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License and Development Agreement

IN WITNESS WHEREOF the parties hereto have caused this Agreement to be executed by their duly authorized officers upon the date first written above.

Avant Immunotherapeutics, Inc. is a party to this Agreement solely with respect to the last sentence of Section 15.13:

EXHIBIT A

CELLDEX PATENT RIGHTS

*

EXHIBIT B

TRANSITION AND DEVELOPMENT PLANS

(attached)

*

EXHIBIT C

STOCK PURCHASE AGREEMENT

(Not attached)

EXHIBIT D

FORM OF PRESS RELEASE

(Not attached)

EXHIBIT E

REDACTED AGREEMENT

(attached)

EXHIBIT F

* CONSENT TO ASSIGNMENT

(Not attached)

EXHIBIT G

ASSIGNMENT AND ASSUMPTION AGREEMENT

(Not attached)

Schedule 4.6(b)

*

Schedule 7.2

Patent Prosecution

*

Schedule 9.1(c)

Patent Representations and Warranties

*

Schedule 9.1(f)

Celldex Research Arrangements

*

Schedule 13.1

Celldex Indemnification

*