Tengion, Inc.

Exhibit 10.24

EXECUTION COPY

Tengion, Inc.

c/o Scheer & Company, Inc.

250 W. Main Street

Branford, CT 06405

July 28, 2004

Tim Bertram, Ph.D., D.V.M

37-1 Mile Creek Road

Old Lyme, CT 06371

Dear Tim:

I am pleased to extend this offer for you to join Tengion, Inc. (the “Company”).

The terms and conditions of the offer are as follows:

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Pursuant to tax regulations, with respect to any stock options you may be granted, in the event that your employment with the Company is terminated for any reason (a) you will have 90 days to exercise the vested portion of such stock options or they will be forfeited and (b) any unvested stock options as of such date of termination shall be cancelled; provided, however, that if your employment terminates by reason of death or disability, and in all events in the case of non-qualified stock options, you or your personal representatives will have twelve (12) months in which to exercise such stock options. In addition, in the event of the termination of your employment by reason of your death, the Company will have the right to repurchase any or all of your vested and unvested restricted stock in accordance with the provisions of the RSPA; and if the Company elects not to repurchase your vested or unvested restricted stock within the twelve (12) month period after the date of such termination of employment, the beneficiaries of your estate will continue to own your restricted stock, subject to the terms of the RSPA, and will be entitled to the appreciation in the value of such restricted stock.

Notwithstanding the foregoing, in the event your employment is terminated by the Company without Cause within six (6) months after the sale or other disposition of all or substantially all of the Company’s assets or a change in ownership of fifty percent (50%) or more of the Company’s stock, in a single transaction or series of related transactions, other than a financing transaction (an “Acquisition Transaction”), and the termination of your employment is the sole, direct and proximate result of the Acquisition Transaction (and not the result of your job performance in whole or in part), your shares shall vest in full (if not sooner vested).

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11 below; and (ii) the term “Fair Market Value” shall mean (A) with respect to any share of the Company’s Preferred Stock, the per share price of the last round of preferred stock financing of the Company; and (B) with respect to any share of the Company’s Common Stock, (x) the per share price of the last share of Common Stock sold, or (y) the exercise price of the last incentive stock option granted or nonqualified stock option granted at fair market value, as determined by the Board, whichever occurred closer to your termination date; provided, however, that in the event that the date of the closing of the last round of preferred stock financing, sale of Common Stock or granting of incentive stock options, as the case may be, was greater than eighteen (18) months prior to your termination date and you disagree with such valuation, you may exercise appraisal rights with respect to such stock in the manner as permitted under Section 262(h) of the General Corporation Law of the State of Delaware

Your employment with the Company will remain “at-will,” meaning that you may terminate your employment with the Company at any time and for any reason simply by notifying the Company. Likewise, the Company may terminate your employment at any time and for any reason, with or without cause or advance notice. This at-will relationship cannot be changed except in a writing signed by the President and CEO. Please understand that your acceptance of this offer of employment should not be based on any promises or representations other than those contained in this letter and attached memorandum. Any promises contrary to the terms of this letter are superceded by this offer letter and such promises are not binding on the Company.

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If the terms and condition of this proposal are acceptable, please so indicate by executing on the line provided below, This proposal may be executed in any number of counterparts all of which when taken together, shall be deemed to be one and the same instrument, and that execution may be delivered by facsimile.

We very much look forward to your joining the Company.

In full understanding and agreement to the terms and conditions of the Company’s conditional offer of employment, including those contained in the attached memorandum, I hereby accept the offer.

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Exhibit A

Performance Objectives/Milestones

In each of the following objectives/milestones, the candidate is responsible for leading and otherwise materially participating along with other members of the management team, Board, advisors, cofounders, etc., in its successful consummation:

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Exhibit B

Confidentiality and Assignment Agreement

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EXECUTION COPY

CONFIDENTIALITY, NON-COMPETITION

AND INVENTION ASSIGNMENT AGREEMENT

As a condition of and in consideration of my employment by Tengion, Inc. a Delaware corporation (the “Company”). I agree to the following terms of this Confidentiality, Non-Competition and Invention Assignment Agreement (the “Agreement”):

1. Confidential Information.

(a) Company Information. I acknowledge that during the course of my employment, I will have access to information about the Company and that my employment with the Company shall bring me into close contact with confidential and proprietary information of the Company. In recognition of the foregoing, I agree, at all times during the term of my employment with the Company and thereafter, to hold in strict confidence, and not to use. except for the benefit of the Company, or to disclose to any person, firm, corporation or other entity without written authorization of the Company, any Confidential Information of the Company (as defined below) which I encounter, obtain, create or develop. I further agree not to make copies of such Confidential Information except as authorized by the Company.

(b) Confidential Information Defined. I understand that “Confidential Information” means any Company proprietary information, technical, business and financial data, trade secrets or know-how, including, but not limited to, research, product plans, products, services, vendor lists supplier lists and suppliers, customer lists and customers (including, but not limited to, customers of the Company on whom I call or, with whom I become acquainted during the term of my employment), contacts at or knowledge of clients or prospective clients of the Company, pricing information and costs, markets, software, ideas, concepts, developments. inventions (including Inventions, as defined in Section 2(b)), discoveries, protocols, scripts, features and modes of operation, interfaces, works of authorship, databases or database criteria, algorithms, methodologies, processes, formulas, computer codes, technology, designs, drawings, internal documentation, engineering materials, hardware configuration information, marketing data, licenses, finances, budgets, projections, forecasts, strategies, salaries, terms of compensation of other employees or other business information disclosed to me by the Company either directly or indirectly in writing, orally or by drawings or observation during the period of my employment with the Company (the “Employment Period”) and any other materials of any nature relating to any matter within the scope of the business of the Company or concerning any of the dealings or affairs of the Company.

(c) Limits on Scope of Confidential Information. I understand that Confidential Information includes, but is not limited to, information pertaining to any aspect of the Company’s business which is either information not known by actual or potential competitors of the Company or is confidential or proprietary information of the Company or its customers or suppliers, whether of a technical nature or otherwise.

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Notwithstanding the foregoing, I understand that Confidential Information shall not include (i) any of the foregoing items which have become publicly known through no wrongful act of mine or of others who were under confidentiality obligations as to the item or items involved; or (ii) any information that I am required to disclose to, or by, any governmental or judicial authority; provided. however, that I give the Company prompt written notice thereof so that the Company may seek an appropriate protective order and/or waive in writing compliance with the confidentiality provisions of this Agreement.

(d) Former Employer Information. I represent that my performance of all terms of this Agreement as an employee of the Company has not breached and will not breach any agreement to keep in confidence proprietary information, knowledge or data acquired by me in confidence or trust prior or subsequent to the commencement of my employment with the Company, and I will not disclose to the Company, or induce the Company to use, any inventions, confidential or proprietary information or material I may have obtained in connection with employment with any prior employer in violation of a confidentiality agreement, nondisclosure agreement or similar agreement with such prior employer.

(e) Third Party Information. I recognize that the Company has received and in the future will receive confidential or proprietary information from third parties subject to a duty on the Company’s part to maintain the confidentiality of such information and to use it only for certain limited purposes. I agree to hold all such confidential or proprietary information in the strictest confidence and not to disclose it to any person, firm or corporation or to use it except as necessary in carrying out my work for the Company consistent with the Company’s agreement with any such third party.

2. Inventions.

(a) Inventions Retained and Licensed. I have attached hereto, as Exhibit A, a list describing with particularity all intellectual property. including, but not limited to, property inventions. copyrights, copyright applications or registrations, original works of authorship, developments, improvements, patents, patent applications, trademarks, trademark applications. trade names or trade secrets which were created or owned by me prior to the commencement of my employment and which belong solely to me or belong to me jointly with another, which relate in any way to any of the Company’s proposed businesses, products or research and development (collectively referred to as “Prior Inventions”), and which are not assigned to the Company hereunder; or, if no such list is attached, I represent that there are no such Prior Inventions. If, in the course of the Employment Period, I agree to incorporate into a Company product, process or machine a Prior Invention owned by me or in which I have an interest, absent a prior written agreement or license between myself and the Company for such incorporation of the Prior Invention into a Company product, process or machine, then the Company is hereby granted and shall have a non-exclusive, royalty-free, irrevocable, perpetual, worldwide license (with the right to sublicense) to make, have made, copy, modify, make derivative works of, use, sell and otherwise distribute such Prior Invention as part of or in connection with such product. process or machine.

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(b) Assignment of Inventions. I agree that I will, without additional compensation, promptly make full written disclosure to the Company, will hold in trust for the sole right and benefit of the Company, and hereby assign to the Company, or its designee, all my right, title and interest throughout the world in and to any and all inventions, original works of authorship. developments, concepts, know-how, improvements or trade secrets, whether or not patentable or registrable under copyright or similar laws, which I may solely or jointly conceive or develop or reduce to practice. or cause to be conceived or developed or reduced to practice, whether or not during regular working hours, during the Employment Period, and with respect to Inventions in the field of tissue engineering and organ regeneration (the “Field of Interest”), for a period of one (1) year thereafter, provided they either (i) relate at the time of conception or development to the actual or demonstrably proposed business or research and development activities of the Company; (ii) result from or relate to any work performed for the Company; or (iii) are developed through the use of Confidential Information and/or Company owned resources or in consultation with Company personnel (collectively referred to as “Inventions”). I further acknowledge that all Inventions which are made by me (solely or jointly with others) within the scope of and during the Employment Period are “works made for hire” (to the greatest extent permitted by applicable law) for which I am, in part, compensated by my salary, unless regulated otherwise by law but that, in the event any such Invention is deemed not to be a work made for hire, I hereby assign all rights in such Invention to the Company. I further represent and agree that to the best of my knowledge and belief, the practice by the Company of any of the Inventions will not violate or infringe upon any right, patent, copyright, trademark or right of privacy, or constitute libel or slander against or violate any other rights of any person, firm or corporation, and that I will use my best efforts to prevent any such violation.

(c) Maintenance of Records. I agree to keep and maintain reasonable and current written records of all Inventions made by me (solely or jointly with others) during the Employment Period. The records may be in the form of notes, sketches, drawings, flow charts, electronic data or recordings, laboratory notebooks, and any other format. The records will be available to and remain the sole property of the Company at all times. I agree not to remove such records from the Company’s place of business except as expressly permitted by Company policy which may, from time to time, be revised at the sole discretion of the Company for the purpose of furthering the Company’s business.

(d) Intellectual Property Rights. I agree to assist the Company, or its designee, at the Company’s expense, in every reasonable way to secure the Company’s rights in the Inventions and any copyrights, copyright applications or registrations, patents, patent applications, trademarks, trademark applications trade names, service marks logos, database rights, algorithms, know-how, domain names, mask work rights, moral rights, or other intellectual property rights relating thereto in any and all countries, including the disclosure to the Company of all pertinent information and data with respect thereto, the execution of all applications, specifications, oaths, assignments, recordations, and all other instruments which the Company shall deem necessary in order to apply for, obtain, maintain and transfer such rights and in order to assign and convey to the Company, its successors, assigns and nominees the sole and exclusive right, title and

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interest in and to such inventions, and any intellectual property or other proprietary rights relating thereto. I further agree that my obligation to execute or cause to be executed, when it is in my power to do so, any such instrument or papers shall continue after the termination of this Agreement until the expiration of the last such intellectual property right to expire in any country of the world. If the Company is unable because of my mental or physical incapacity or unavailability for any other reason to secure my signature to apply for or to pursue any application for any United States or foreign patents or copyright registrations covering Inventions or original works of authorship assigned to the Company as above, then I hereby irrevocably designate and appoint the Company and its duly authorized officers and agents as my agent and attorney in fact, to act for and in my behalf and stead to execute and file any such applications or records and to do all other lawfully permitted acts to further the application for, prosecution, issuance, maintenance or transfer of letters patent or registrations thereon with the same legal force and effect as if originally executed by me. I hereby waive and irrevocably quitclaim to the Company any and all claims, of any nature whatsoever, which I now or hereafter have for past, present or future infringement of any and all proprietary rights assigned to the Company.

3. Returning Company Documents. I agree that, at the time of termination of my employment with the Company for any reason. I will deliver to the Company (and will not keep in my possession, recreate or deliver to anyone else) any and all Confidential Information and all other documents, materials, information or property developed by me pursuant to my employment or otherwise belonging to the Company, its successors or assigns. I further agree that any property situated on the Company’s premises and owned by the Company, including disks and other storage media, filing cabinets or other work areas, is subject to inspection by Company personnel at any time with or without notice. In the event of the termination of my employment, I agree to sign and deliver the “Termination Certification” attached hereto as Exhibit B.

4. Disclosure of Agreement. During the Restricted Period (as defined below). I will disclose the existence of this Agreement to any prospective employer, partner, co-venturer, investor or lender prior to entering into an employ mint partnership or other business relationship with such person or entity; provided, however, the foregoing shall not, obligate me to disclose the existence of this Agreement when I am engaging in activities unrelated to the business of the Company.

5. Solicitation of Employees and Clients. I recognize and acknowledge that during my employment with the Company, I will have access to, learn, be provided with and, in some cases, prepare and create certain Confidential Information, all of which is of substantial value to the Company’s business. I further recognize that I will have substantial contacts with customers, clients, investors, consultants, contractors and strategic partners of the Company and hereby acknowledge a fiduciary relationship will exist between me and the Company by reason of my having received and been privy to client, customer and other proprietary information which would give me an unfair advantage in attracting the Company’s clients and customers or otherwise competing against the Company. In light of the foregoing, during the Employment Period and for a period of twenty four (24) months after the date of the termination of my employment for any reason (the “Restricted Period”), I shall not, without the prior written

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consent of the Company, directly or indirectly. either individually or on behalf of or through any other person. business, enterprise or entity (other than the Company), (i) solicit or induce, or in any manner attempt to solicit or induce, any person employed by, an agent of, or a service provider to, the Company to terminate such person’s employment, agency or service as the case may be, with the Company; or (ii) divert, or attempt to divert, any person, concern, or entity from doing business with the Company, or attempt to induce any such person, concern or entity to cease being a customer or supplier of the Company.

6. Non-Competition. I agree that , during the term of my relationship with the Company (whether as an employee, consultant or otherwise), and for a period of twelve (12) months immediately following the termination of my relationship with the Company for any reason, with or without cause (the “Non-Compete Period”), I will not, without the prior written consent of the Company, for myself or on behalf of any other person or entity, directly or indirectly, either as principal, agent, employee, consultant, representative or in any other capacity, own, manage, operate or control, or be connected or employed by, or otherwise associate in any manner with, or engage in any business which is in the Field of Interest within the United States.

7. Reasonableness of Restrictions. I recognize and acknowledge that the restrictions and limitations set forth in this Agreement, including such provisions set forth in Sections 5 and 6 above, are legitimate and fair in light of my access to Confidential Information, my substantial contacts with clients of the Company and the Company’s need to develop, market and sell its services and/or products. I further acknowledge that the restrictions and limitations set forth in this Agreement will, in no way interfere with my ability to earn a living following the termination of my employment with the Company and that my ability to earn a livelihood without violating such restrictions is a material condition to my employment with the Company.

8. Independence. Each of the rights enumerated above shall be independent of the others and shall be in addition to and not in lieu of any other rights and remedies available to the Company at law or in equity.

9. Severability. If any provision/s and/or covenant/s contained herein or any part of any of them is hereafter construed or adjudicated to he invalid or unenforceable, the same shall not affect the remainder of the provision/s and/or covenant/s or rights or remedies, which shall be given full effect without regard to the invalid or unenforceable portions. Additionally, in the event any provisions and/or covenants contained herein an held to be invalid or unenforceable because of the duration area, scope, activity and/or subject contemplated under such provision/s and/or covenant/s. I agree that the court making such determination shall have the power to reduce the applicable duration, area, scope, activity and/or subject to the maximum and/or broadest extent permissible by law and that, in its reduced form, said provision/s and/or covenant/s shall then be enforceable. I further acknowledge that in the event any provision/s and/or covenant/s contained herein or any part of any of them is hereafter construed or adjudicated to be invalid or unenforceable in any particular jurisdiction, then, any such invalidity or unenforceability shall not invalidate or render unenforceable such provision and/or covenant in any other jurisdiction.

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10. Injunctive Relief. I expressly acknowledge that any breach or threatened breach of any of the terms and/or conditions set forth in this Agreement may result in substantial, continuing and irreparable injury to the Company. Therefore, I hereby agree that, in addition to any other remedy that may be available to the Company, the Company may be entitled to injunctive relief, specific performance or other equitable relief by a court of appropriate jurisdiction in the event of any breach or threatened breach of the terms of this Agreement. Notwithstanding any other provision to the contrary, I acknowledge and agree that the Restricted Period or the Non-Compete Period, as applicable, shall be tolled during any period of violation of any of the covenants in Section 5 or Section 6 hereof and during any other period required for litigation during which the Company seeks to enforce such covenants against me if it is ultimately determined that I was in breach of such covenants.

11. General Provisions.

(a) Governing Law and Forum Selection. The validity, interpretation, construction and performance of this Agreement shall be governed by the laws of the United States of America and the Commonwealth of Pennsylvania, without giving effect to the principles of conflict of laws. I agree that any disputes that may arise from this Agreement shall be resolved in State or Federal courts located in the Commonwealth of Pennsylvania, exclusively, and consent to the jurisdiction of such courts.

(b) Notices. All notices or other communications given hereunder shall be in writing and shall be deemed effective upon delivery at the address of the party to be notified and shall be mailed by certified or registered mail, return receipt requested, delivered by courier, telecopied, or sent by other facsimile method (notices by telecopy or facsimile must be confirmed by next day courier delivery to be effective), addressed to the address specified below, or such other address as such party may subsequently notify the other party of in writing.

(c) Entire Agreement. This Agreement sets forth the entire agreement and understanding between the Company and me relating to the subject matter herein and merges all prior discussions between us. No modification or amendment to this Agreement, nor any waiver of any rights under this Agreement, will be effective unless in writing signed by the party to be charged. Any subsequent change or changes in my duties, obligations, rights or compensation will not affect the validity or scope of this Agreement.

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(d) Successors and Assigns. This Agreement will be binding upon my heirs, executors, administrators and other legal representatives and will be for the benefit of the Company, its successors, and its assigns.

(e) Fees and Expenses. I hereby agree that if the Company commences an action against me, by way of claim or counterclaim and including declaratory claims, in which it is preliminarily or finally determined that I have violated any provision of this Agreement, I agree to reimburse the Company for all cost and expenses incurred in such action, including but not limited to, the Company’s reasonable attorneys’ fees.

(f) Waiver. The Company’s waiver or failure to enforce the terms of this Agreement or any similar agreement in any one instance shall not constitute a waiver of its rights hereunder with respect to other violations of this Agreement.

(g) Survival. The provisions of this Agreement shall survive the termination of my relationship and employment with the Company and/or the assignment of this Agreement by the Company to any successor in interest or other assignee.

[Remainder of this page intentionally left blank]

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I, Tim Bertram, Ph.D., D.V.M have executed this Confidentiality, Non-Competition and Invention Assignment Agreement on the respective date set forth below:

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EXHIBIT A

LIST OF PRIOR INVENTIONS

AND ORIGINAL WORKS OF AUTHORSHIP

EXCLUDED FROM SECTION 2 OF THE AGREEMENT

Date: 28 July 04

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EXHIBIT B

TERMINATION CERTIFICATION

This is to certify that I do not have in my possession, nor have I failed to return, any devices, records, data, notes, reports, proposals, lists, correspondence, specifications, drawings, blueprints, sketches, materials, equipment or reproductions of any of the aforementioned items and any Confidential Information (as defined in the Company’s Confidentiality, Non-Competition and Invention Assignment Agreement signed by me; the “Agreement”) belonging to the Company.

I further certify that I have complied with all the terms of the Agreement, including the reporting of any inventions and original works of authorship, developments, concepts, improvements or trade secrets, whether or not patentable or registrable, under copyright or similar laws, conceived or made by me (solely or jointly with others) covered by the Agreement.

I further agree that, in compliance with the Agreement, I will preserve as confidential all trade secrets, confidential knowledge, data or other proprietary information relating to products, processes, know-how, designs, formulas, developmental or experimental work, computer programs, data bases, other original works of authorship, customer lists, business plans, financial information or other subject matter pertaining to any business of the Company or any of its employees, clients, consultants or licenses.

I further agree that for twenty four (24) months from this date, I will not hire any employees, of the Company and I will not solicit, induce, recruit or encourage any of the Company’s employees to leave their employment.

I further agree that for twelve (12) months from this date, I will refrain from engaging, in any capacity, in any business which is in the Field of Interest (as such term is defined in the Agreement) within the United States.

Date: 28 July 04

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Exhibit C

President and CEO

Tengion, Inc.

c/o Scheer & Company, Inc.

250 W. Main Street

Branford, CT 06405

I represent that to the best of my understanding, I am under no common law or contractual obligation that would be an impediment to my employment with Tengion, Inc. (the “Company”). I will not use or disclose any confidential, proprietary or trade secret information belonging to any former employer, in my employment with the Company.

I represent and warrant that I have not retained or copied any confidential, proprietary or trade secret information or property, in any form, belonging to any former employer, and that if I was in possession of any such information or property, I have returned it to my former employer(s).

I agree that, if at any time during my employment with the Company, I am at risk of using or disclosing any confidential, proprietary or trade secret information belonging to any former employer, I will immediately recuse myself from acting on the matter and advise the President and CEO of the Company, without revealing any protected information, the nature of my conflict; provided, however, that I will not be required to recuse myself in the event such disclosure is required by law or regulation or as a result of a response to a valid order of a court or another governmental body of the United States or any political subdivision thereof.

I understand that if any of the representations or warranties herein are intentionally false, or if I violate any of the terms of this memorandum, I will forfeit any unvested portion of the award of 260,000 shares of restricted stock and any other unvested stock incentives awarded or issued to me.

Dated: 28 July, 2004

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