SUBSCRIPTION AGREEMENT

Exhibit 10.2

SUBSCRIPTION AGREEMENT

GTC Biotherapeutics, Inc.

175 Crossing Boulevard

Framingham, MA 01702

The undersigned (the “Investor”) hereby confirms its agreement with you as follows:

1. This Subscription Agreement (this “Agreement”) is made as of the date set forth below between GTC Biotherapeutics, Inc., a Massachusetts corporation (the “Company”), and the Investor.

2. The Company has authorized the sale and issuance to certain investors of up to an aggregate of 12,000,000 units (the “Units”), each consisting of (i) one share (the “Share” and collectively the “Shares”) of its Common Stock, par value $0.01 per share (the “Common Stock”) and (ii) one warrant (the “Warrant” and collectively the “Warrants”) to purchase .65 Shares of Common Stock (and the fractional amount being the “Warrant Ratio”), in substantially the form attached hereto as Exhibit A, subject to adjustment by the Company’s Board of Directors, or a committee thereof, for a purchase price of $1.46125 per Unit (the “Purchase Price”). The shares issuable upon the exercise of the Warrants are referred to herein as the “Warrant Shares” and, together with the Units, the Shares and the Warrants, are referred to herein as the “Securities”.

3. The offering and sale of the Securities (the “Offering”) is being made pursuant to an effective Registration Statement on Form S-3 (including the Prospectus contained therein (the “Base Prospectus”) and the exhibits thereto and the documents incorporated therein by reference, the “Registration Statement”) filed by the Company with the Securities and Exchange Commission (the “Commission”), if applicable, certain preliminary prospectuses and/or “free writing prospectuses” (as that term is defined in Rule 405 under the Securities Act of 1933, as amended), that have or will be filed with the Commission and delivered to the Investor on or prior to the date hereof (the “Time of Sale Prospectus”), and a Prospectus Supplement (the “Prospectus Supplement”) containing certain supplemental information regarding the Shares and terms of the Offering that will be filed with the Commission and delivered, or otherwise made available, to the Investor along with the Company’s counterpart to this Agreement.

4. The Company and the Investor agree that the Investor will purchase from the Company and the Company will issue and sell to the Investor the Units as set forth below for the aggregate purchase price set forth below. The Units shall be purchased pursuant to the Terms and Conditions for Purchase of Units attached hereto as Annex I and incorporated herein by this reference as if fully set forth herein.

5. The manner of settlement of the Shares included in the Units and purchased by the Investor shall be determined by such Investor as follows (check one):

U.S. Bank

ABA No.: 091000022

Corporate Trust Services

Acct. No.: 173103321050

Ref: GTC Therapeutics Subscription Escrow

– OR –

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IT IS THE INVESTOR’S RESPONSIBILITY TO (A) MAKE THE NECESSARY WIRE TRANSFER OR CONFIRM THE PROPER ACCOUNT BALANCE IN A TIMELY MANNER AND (B) ARRANGE FOR SETTLEMENT BY WAY OF DWAC OR DVP IN A TIMELY MANNER. IF THE INVESTOR DOES NOT DELIVER THE AGGREGATE PURCHASE PRICE FOR THE UNITS OR DOES NOT MAKE PROPER ARRANGEMENTS FOR SETTLEMENT IN A TIMELY MANNER, THE SHARES AND WARRANTS MAY NOT BE DELIVERED AT CLOSING TO THE INVESTOR OR THE INVESTOR MAY BE EXCLUDED FROM THE CLOSING ALTOGETHER.

6. The executed Warrant shall be delivered in accordance with the terms thereof.

7. The Investor represents that, except as set forth below, (a) it has had no position, office or other material relationship within the past three years with the Company or persons known to it to be affiliates of the Company, (b) it is not a NASD member or an Associated Person (as such term is defined under the NASD Membership and Registration Rules Section 1011) as of the Closing, and (c) neither the Investor nor any group of Investors (as identified in a public filing made with the Commission) of which the Investor is a part in connection with the Offering of the Units, acquired, or obtained the right to acquire, 20% or more of the Common Stock (or securities convertible into or exercisable for Common Stock) or the voting power of the Company on a post-transaction basis. Exceptions:

(If no exceptions, write “none.” If left blank, response will be deemed to be “none.”)

8. The Investor represents that it has received the final Base Prospectus, dated July 7, 2006, which is a part of the Company’s Registration Statement, and any free writing prospectus, prior to or in connection with the receipt of this Agreement (collectively, the “Disclosure Package”) and the Prospectus Supplement along with the Company’s counterpart to this Agreement .

9. No offer by the Investor to buy Units will be accepted and no part of the Purchase Price will be delivered to the Company until the Company has accepted such offer by countersigning a copy of this Agreement, and any such offer may be withdrawn or revoked, without obligation or commitment of any kind, at any time prior to the Company (or a Placement Agent on behalf of the Company) sending (orally, in writing, or by electronic mail) notice of its acceptance of such offer. An indication of interest will involve no obligation or commitment of any kind until this Agreement is accepted and countersigned by or on behalf of the Company.

Number of Units:                     

Purchase Price Per Unit: $1.46125

Aggregate Purchase Price: $                    

Please confirm that the foregoing correctly sets forth the agreement between us by signing in the space provided below for that purpose.

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ANNEX I

TERMS AND CONDITIONS FOR PURCHASE OF UNITS

1. Authorization and Sale of the Units. Subject to the terms and conditions of this Agreement, the Company has authorized the sale of the Units, which consist of the Shares and the Warrants.

2. Agreement to Sell and Purchase the Units; Placement Agents.

2.1 At the Closing (as defined in Section 3.1), the Company will sell to the Investor, and the Investor will purchase from the Company, upon the terms and conditions set forth herein, the number of Units set forth on the last page of the Agreement to which these Terms and Conditions for Purchase of Units are attached as Annex I (the “Signature Page”) for the aggregate purchase price therefor set forth on the Signature Page.

2.2 The Company proposes to enter into substantially this same form of Subscription Agreement with certain other investors (the “Other Investors”) and expects to complete sales of Units to them. The Investor and the Other Investors are hereinafter sometimes collectively referred to as the “Investors,” and this Agreement and the Subscription Agreements executed by the Other Investors are hereinafter sometimes collectively referred to as the “Agreements.”

2.3 Investor acknowledges that the Company intends to pay C.E. Unterberg, Towbin, LLC, Rodman & Renshaw, LLC and Oppenheimer & Co. Inc. (together, the “Placement Agents”) a fee (the “Placement Fee”) in respect of the sale of Units to the Investor.

2.4 The Company has entered into a Placement Agent Agreement (the “Placement Agreement”) with the Placement Agents that contains certain representations and warranties, covenants, agreements and indemnities of the Company to the Placement Agents that may be relied upon by the Investor, which shall be a third party beneficiary thereof. As a condition to closing, the Company shall cause its counsel to issue to the Investor or to permit the Investor to rely on any legal opinions being issued to the Placement Agent in connection with the transactions contemplated hereby. A copy of the Placement Agreement is available upon request.

3. Closings and Delivery of the Units and Funds.

3.1 Closing. The completion of the purchase and sale of the Units (the “Closing”) will occur at a place and time (the “Closing Date”) to be specified by the Company and the Placement Agents, and of which the Investors will be notified in advance by the Placement Agents. At the Closing, (a) the Company will cause the Transfer Agent to deliver to the Investor the number of Shares (and Units) set forth on the Signature Page registered in the name of the Investor or, if so indicated on the Investor Questionnaire attached hereto as Exhibit B, in the name of a nominee designated by the Investor, (b) the Company shall cause to be delivered to the Investor a Warrant to purchase the number of whole Warrant Shares

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determined by multiplying the number of Shares (and Units) set forth on the signature page by the Warrant Ratio and rounding down to the nearest whole number and (c) the aggregate purchase price for the Units being purchased by the Investor will be delivered by or on behalf of the Investor to the Company.

3.2 (a) Conditions to the Company’s Obligations. The Company’s obligation to issue the Shares and the Warrants to the Investor will be subject to the receipt by the Company of the purchase price for the Units being purchased hereunder as set forth on the Signature Page and the accuracy of the representations and warranties made by the Investor and the fulfillment of those undertakings of the Investor to be fulfilled prior to the Closing Date.

(b) Conditions to the Investor’s Obligations. The Investor’s obligation to purchase the Units will be subject to the accuracy of the representations and warranties made by the Company and the fulfillment of those undertakings of the Company to be fulfilled prior to the Closing Date, including, without limitation, those contained in the Placement Agent Agreement (collectively, the “Company Closing Conditions”) , and to the condition that the Placement Agent shall not have: (1) terminated the Placement Agreement pursuant to the terms thereof or (2) determined that the conditions to the closing in the Placement Agreement have not been satisfied. The Investor’s obligations are expressly not conditioned on the purchase by any or all of the Other Investors of the Units that they have agreed to purchase from the Company.

3.3 Delivery of Funds.

(a) Delivery by Electronic Book-Entry at The Depository Trust Company. If the Investor elects to settle the Shares purchased by such Investor through delivery by electronic book-entry at DTC, no later than one (1) business day after the execution of this Agreement by the Investor and the Company, the Investor shall remit by wire transfer the amount of funds equal to the aggregate purchase price for the shares being purchased by the Investor to the following account designated by the Company and the Placement Agents pursuant to the terms of that certain Escrow Agreement (the “ Escrow Agreement”) dated as of July 18, 2006, by and among the Company, the Placement Agents and U.S. Bank National Association (the “Escrow Agent”):

U.S. Bank

ABA No.: 091000022

Corporate Trust Services

Acct. No.: 173103321050

Ref: GTC Therapeutics Subscription Escrow

Such funds shall be held in escrow until the Closing and delivered by the Escrow Agent on behalf of the Investors to the Company upon the satisfaction, in the sole judgment of the Placement Agents, of the Company Closing Conditions. The Placement Agents shall have no rights in or to any of the escrowed funds, unless the Placement Agents and the Escrow Agent are notified in writing by the Company in connection with the Closing that a portion of the escrowed funds shall be applied to the Placement Fee. The Company and the Investor agree to indemnify

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and hold the Escrow Agent harmless from and against any and all losses, costs, damages, expenses and claims (including, without limitation, court costs and reasonable attorneys fees) (“Losses”) arising under this Section 3.3 or otherwise with respect to the funds held in escrow pursuant hereto or arising under the Escrow Agreement, unless it is finally determined that such Losses resulted directly from the willful misconduct or gross negligence of the Escrow Agent. Anything in this Agreement to the contrary notwithstanding, in no event shall the Escrow Agent be liable for any special, indirect or consequential loss or damage of any kind whatsoever (including but not limited to lost profits), even if the Escrow Agent has been advised of the likelihood of such loss or damage and regardless of the form of action.

Investor shall also furnish to the Placement Agents a completed W-9 form (or, in the case of an Investor who is not a United States citizen or resident, a W-8 form).

(b) Delivery Versus Payment through The Depository Trust Company. If the Investor elects to settle the Shares purchased by such Investor by delivery versus payment through DTC, no later than one (1) business day after the execution of this Agreement by the Investor and the Company, the Investor shall confirm that the account or accounts at C.E. Unterberg, Towbin, LLC to be credited with the Shares being purchased by the Investor have a minimum balance equal to the aggregate purchase price for the Units being purchased by the Investor.

3.4 Delivery of Shares.

(a) Delivery by Electronic Book-Entry at The Depository Trust Company. If the Investor elects to settle the Shares purchased by such Investor through delivery by electronic book-entry at DTC, no later than one (1) business day after the execution of this Agreement by the Investor and the Company, the Investor shall direct the broker-dealer at which the account or accounts to be credited with the Shares being purchased by such Investor are maintained, which broker/dealer shall be a DTC participant, to set up a Deposit/Withdrawal at Custodian (“DWAC”) instructing American Stock Transfer & Trust Company, the Company’s transfer agent, to credit such account or accounts with the Shares by means of an electronic book-entry delivery. Such DWAC shall indicate the settlement date for the deposit of the Shares, which date shall be provided to the Investor by the Placement Agents. Simultaneously with the delivery to the Company by the Escrow Agent of the funds held in escrow pursuant to Section 3.3 above, the Company shall direct its transfer agent to credit the Investor’s account or accounts with the Shares pursuant to the information contained in the DWAC.

(b) Delivery Versus Payment through The Depository Trust Company. If the Investor elects to settle the Shares purchased by such Investor by delivery versus payment through DTC, no later than one (1) business day after the execution of this Agreement by the Investor and the Company, the Investor shall notify C.E. Unterberg, Towbin, LLC of the account or accounts at C.E. Unterberg, Towbin, LLC to be credited with the Shares being purchased by such Investor. On the Closing Date, the Company shall deliver the Shares to the Investor directly to the account(s) at C.E. Unterberg, Towbin, LLC identified by Investor and simultaneously therewith payment shall be made from such account(s) to the Company through DTC.

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4. Representations, Warranties and Covenants of the Investor.

4.1 The Investor represents and warrants to, and covenants with, the Company that (a) the Investor is knowledgeable, sophisticated and experienced in making, and is qualified to make decisions with respect to, investments in shares presenting an investment decision like that involved in the purchase of the Units, including investments in securities issued by the Company and investments in comparable companies, and has requested, received, reviewed and considered all information it deemed relevant in making an informed decision to purchase the Units, (b) the Investor has answered all questions on the Signature Page and the Investor Questionnaire for use in preparation of the Prospectus Supplement and the answers thereto are true and correct as of the date hereof and will be true and correct as of the Closing Date, and (c) the Investor, in connection with its decision to purchase the number of Units set forth on the Signature Page, is relying only upon the Disclosure Package, the documents incorporated by reference therein and the representations and warranties of the Company contained herein.

4.2 The Investor acknowledges, represents and agrees that no action has been or will be taken in any jurisdiction outside the United States by the Company or any Placement Agent that would permit an offering of the Units, or possession or distribution of offering materials in connection with the issue of the Units in any jurisdiction outside the United States where action for that purpose is required. Each Investor outside the United States will comply with all applicable laws and regulations in each foreign jurisdiction in which it purchases, offers, sells or delivers Units or has in its possession or distributes any offering material, in all cases at its own expense. The Placement Agents are not authorized to make and have not made any representation or use of any information in connection with the issue, placement, purchase and sale of the Units, except as set forth or incorporated by reference in the Disclosure Package or the Prospectus.

4.3 The Investor further represents and warrants to, and covenants with, the Company that (a) the Investor has full right, power, authority and capacity to enter into this Agreement and to consummate the transactions contemplated hereby and has taken all necessary action to authorize the execution, delivery and performance of this Agreement, and (b) this Agreement constitutes a valid and binding obligation of the Investor enforceable against the Investor in accordance with its terms, except as enforceability may be limited by applicable bankruptcy, insolvency, reorganization, moratorium or similar laws affecting creditors’ and contracting parties’ rights generally and except as enforceability may be subject to general principles of equity (regardless of whether such enforceability is considered in a proceeding in equity or at law) and except as the indemnification agreements of the Investors herein may be legally unenforceable.

4.4 The Investor understands that nothing in this Agreement or any other materials presented to the Investor in connection with the purchase and sale of the Shares constitutes legal, tax or investment advice. The Investor has consulted such legal, tax and investment advisors as it, in its sole discretion, has deemed necessary or appropriate in connection with its purchase of Units.

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4.5 The Investor represents, warrants and agrees that, since the earlier to occur of (i) the date on which the Placement Agents first contacted the Investor about the Offering and (ii) the date that is the tenth (10) trading day prior to the date of this Agreement, it has not engaged in any short selling of the Company’s securities, or established or increased any “put equivalent position” as defined in Rule 16(a)-1(h) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”) with respect to the Company’s securities.

5. Representations, Warranties and Covenants of the Company. The Company represents and warrants to, and agrees with, the Investor that:

5.1 The Company has prepared and filed in conformity with the requirements of the Securities Act of 1933, as amended (the “Securities Act”), and published rules and regulations thereunder (the “Rules and Regulations”) adopted by the Securities and Exchange Commission (the “Commission”) a “shelf” Registration Statement (as hereinafter defined) on Form S-3 as amended (No. 333-135054), which became effective on July 7, 2006 (the “Effective Date”), including a base prospectus relating to the Securities (the “Base Prospectus”), and such amendments and supplements thereto as may have been required to the date of this Agreement. The term “Registration Statement” as used in this Agreement means the registration statement (including all exhibits, financial schedules and all documents and information deemed to be a part of the Registration Statement pursuant to Rule 430A or 434(d) under the Securities Act), as amended or supplemented to the date of this Agreement, including the Base Prospectus. The Registration Statement is effective under the Securities Act and no stop order preventing or suspending the effectiveness of the Registration Statement or suspending or preventing the use of the Prospectus has been issued by the Commission and no proceedings for that purpose have been instituted or, to the knowledge of the Company, are threatened by the Commission. The Company, if required by the Rules and Regulations of the Commission, proposes to file the Prospectus (as defined below), with the Commission pursuant to Rule 424(b) of the Rules and Regulations. The term “Prospectus” as used in this Agreement means the Prospectus, in the form in which it is to be filed with the Commission pursuant to Rule 424(b) of the Rules and Regulations, or, if the Prospectus is not to be filed with the Commission pursuant to Rule 424(b), the Prospectus in the form included as part of the Registration Statement as of the Effective Date, except that if any revised prospectus or prospectus supplement shall be provided to the Placement Agents by the Company for use in connection with the offering and sale of the Units which differs from the Prospectus (whether or not such revised prospectus or prospectus supplement is required to be filed by the Company pursuant to Rule 424(b) of the Rules and Regulations), the term “Prospectus” shall refer to such revised prospectus or prospectus supplement, as the case may be, from and after the time it is first provided to the Placement Agents for such use. Any preliminary prospectus or prospectus subject to completion included in the Registration Statement or filed with the Commission pursuant to Rule 424 under the Securities Act is hereafter called a “Preliminary Prospectus.” Any reference herein to the Registration Statement, any Preliminary Prospectus or the Prospectus shall be deemed to refer to and include the documents incorporated by reference therein pursuant to Item 12 of Form S-3 which were filed under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), on or before the last to occur of the Effective Date, the date of the Preliminary Prospectus, or the date of the Prospectus, and any reference herein to the terms “amend,” “amendment,” or “supplement” with respect to the Registration Statement, any Preliminary Prospectus or the

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Prospectus shall be deemed to refer to and include (i) the filing of any document under the Exchange Act after the Effective Date, the date of such Preliminary Prospectus or the date of the Prospectus, as the case may be, which is incorporated by reference and (ii) any such document so filed, but excluding any documents or information furnished to the Commission under Item 2.02 or Item 7.01 of any Current Report on Form 8-K. If the Company has filed an abbreviated registration statement to register additional Securities pursuant to Rule 462(b) under the Rules (the “462(b) Registration Statement”), then any reference herein to the Registration Statement shall also be deemed to include such 462(b) Registration Statement.

5.2 As of the Applicable Time (as defined below) and as of the Closing Date, neither (i) the General Use Free Writing Prospectus (as defined below), if any, issued at or prior to the Applicable Time, and the Pricing Prospectus (as defined below) and the information included on Schedule B to the Placement Agent Agreement (the “Placement Agent Agreement”) by and among the Company and the Placement Agents of even date herewith (the “Pricing Information”), if any, all considered together (collectively, the “General Disclosure Package”), nor (ii) any individual Limited Use Free Writing Prospectus (as defined below), if any, when considered together with the General Disclosure Package, included or will include any untrue statement of a material fact or omitted or will omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided, however, that the Company makes no representations or warranties as to information contained in or omitted from any Issuer Free Writing Prospectus, in reliance upon, and in conformity with, written information furnished to the Company by the Placement Agents specifically for inclusion therein, which information the parties hereto agree is limited to the Placement Agents’ Information (as defined in Section 16 of the Placement Agent Agreement). As used in this Section 5.2 and elsewhere in this Agreement:

“Applicable Time” means 4:30 P.M., New York time, on the date of this Agreement.

“Pricing Prospectus” means the Preliminary Prospectus, if any, and the Base Prospectus, each as amended and supplemented as of immediately prior to the Applicable Time, including any document incorporated by reference therein and any prospectus supplement deemed to be a part thereof.

“Issuer Free Writing Prospectus” means any “issuer free writing prospectus,” as defined in Rule 433 under the Securities Act relating to the Securities in the form filed or required to be filed with the Commission or, if not required to be filed, in the form retained in the Company’s records pursuant to Rule 433(g) under the Securities Act.

“General Use Free Writing Prospectus” means any Issuer Free Writing Prospectus that is identified on Schedule A to the Placement Agent Ageement.

“Limited Use Free Writing Prospectuses” means any Issuer Free Writing Prospectus that is not a General Use Free Writing Prospectus.

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5.3 No order preventing or suspending the use of any Preliminary Prospectus, any Issuer Free Writing Prospectus or the Prospectus relating to the proposed offering of the Units has been issued by the Commission, and no proceeding for that purpose or pursuant to Section 8A of the Securities Act has been instituted or, to the knowledge of the Company, is threatened by the Commission, and each Preliminary Prospectus, if any, at the time of filing thereof, conformed in all material respects to the requirements of the Securities Act and the Rules and Regulations, and did not contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided, however, that the Company makes no representations or warranties as to information contained in or omitted from any Preliminary Prospectus, in reliance upon, and in conformity with, written information furnished to the Company by the Placement Agents specifically for inclusion therein, which information the parties hereto agree is limited to the Placement Agents’ Information (as defined in Section 16 of the Placement Agent Agreement).

5.4 At the time the Registration Statement and any amendments thereto became effective, at the date of this Agreement and at the Closing Date, the Registration Statement and any amendments thereto conformed and will conform in all material respects to the requirements of the Securities Act and the Rules and Regulations and at the effective time, at the date of this Agreement and at the Closing Date, did not and will not contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading; and the Pricing Prospectus and Prospectus and any amendments or supplements thereto, at time the Pricing Prospectus and Prospectus or any amendment or supplement thereto was issued and at the Closing Date, conformed and will conform in all material respects to the requirements of the Securities Act and the Rules and Regulations and did not and will not contain an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in light of the circumstances under which they were made, not misleading; provided, however, that the foregoing representations and warranties in this paragraph (d) shall not apply to information contained in or omitted from the Registration Statement or the Pricing Prospectus and Prospectus, or any amendment or supplement thereto, in reliance upon, and in conformity with, written information furnished to the Company by the Placement Agents specifically for inclusion therein, which information the parties hereto agree is limited to the Placement Agents’ Information (as defined in Section 16 of the Placement Agent Agreement).

5.5 Each Issuer Free Writing Prospectus, if any, as of its issue date and at all subsequent times through the completion of the public offer and sale of the Units or until any earlier date that the Company notified or notifies the Placement Agent as described in Section 4(e) of the Placement Agent Agreement, did not, does not and will not include any information that conflicted, conflicts or will conflict with the information contained in the Registration Statement, Pricing Prospectus or the Prospectus, including any document incorporated by reference therein and any prospectus supplement deemed to be a part thereof that has not been superseded or modified, or included or would include an untrue statement of a material fact or omitted or would omit to state a material fact required to be stated therein or necessary in order to make the statements therein, in the light of the circumstances prevailing at the subsequent time, not misleading. The foregoing sentence does not apply to statements in or omissions from

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any Issuer Free Writing Prospectus in reliance upon, and in conformity with, written information furnished to the Company by the Placement Agent specifically for inclusion therein, which information the parties hereto agree is limited to the Placement Agents’ Information (as defined in Section 16 of the Placement Agent Agreement).

5.6 The documents incorporated by reference in the Registration Statement, the Pricing Prospectus and the Prospectus, when they became effective or were filed with the Commission, as the case may be, conformed in all material respects to the requirements of the Securities Act or the Exchange Act, as applicable, and the rules and regulations of the Commission thereunder and none of such documents contained any untrue statement of a material fact or omitted to state any material fact required to be stated therein or necessary to make the statements therein, in light of the circumstances under which they were made, not misleading; and any further documents so filed and incorporated by reference in the Registration Statement, the Pricing Prospectus and the Prospectus, when such documents become effective or are filed with the Commission , as the case may be, will conform in all material respects to the requirements of the Securities Act or the Exchange Act, as applicable, and the rules and regulations of the Commission thereunder and will not contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein, in light of the circumstances under which they were made, not misleading.

5.7 The Company has not, directly or indirectly, distributed and will not distribute any offering material in connection with the offering and sale of the Units other than any Preliminary Prospectus, the Pricing Prospectus and the Prospectus and other materials, if any, permitted under the Securities Act and consistent with Section 4(b) of the Placement Agent Agreement. The Company will file with the Commission all Issuer Free Writing Prospectuses, if any, in the time and manner required under Rules 164(b)(2) and 433(d) under the Securities Act.

5.8 The Company has been duly organized and is validly existing as a corporation in good standing (or the equivalent thereof, if any) under the laws of its jurisdiction of incorporation, is duly qualified to do business and is in good standing (or the equivalent thereof, if any) as a foreign corporation in each jurisdiction in which its ownership or lease of property or the conduct of its businesses requires such qualification, and has all power and authority necessary to own or hold its properties and to conduct the businesses in which it is engaged, except where the failure to be so qualified and in good standing or have such power or authority would not have, individually or in the aggregate, a material adverse effect on the condition (financial or otherwise), results of operations, business, properties or prospects of the Company and its subsidiaries taken as a whole (a “Material Adverse Effect”).

5.9 The Shares to be issued and sold by the Company hereunder and under the Subscription Agreements and the Warrant Shares, which are issuable upon exercise of the Warrants, have been duly and validly authorized and, when issued and delivered against payment therefor as provided herein, will be duly and validly issued, fully paid and nonassessable and free of any preemptive or similar rights. The Securities conform to the descriptions thereof contained in the General Disclosure Package.

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5.10 The Company has an authorized capitalization as set forth in the General Disclosure Package. All of the issued and outstanding shares of capital stock of the Company have been duly and validly authorized and issued, are fully paid and non-assessable, have been issued in compliance with federal and state securities laws, and conform to the description thereof contained in the General Disclosure Package. None of the outstanding shares of Common Stock was issued in violation of any preemptive rights, rights of first refusal or other similar rights to subscribe for or purchase securities of the Company. There are no authorized or outstanding shares of capital stock, options, warrants, preemptive rights, rights of first refusal or other rights to purchase, or equity or debt securities convertible into or exchangeable or exercisable for, any capital stock of the Company or any of its subsidiaries other than those described in the General Disclosure Package. The description of the Company’s stock option, stock bonus and other stock plans or arrangements, and the options or other rights granted thereunder, as described in the General Disclosure Package, completely, accurately and fairly present the information required to be shown with respect to such plans, arrangements, options and rights.

5.11 The Company has the full right, power and authority to enter into this Agreement and the Warrant and to perform and to discharge its obligations hereunder and thereunder; and each of this Agreement and the Warrant has been duly authorized, executed and delivered by the Company, and constitutes a valid and binding obligation of the Company enforceable in accordance with its terms, except as limited by (i) applicable bankruptcy, insolvency, reorganization, moratorium and other laws of general application affecting the enforcement of creditors’ rights generally and (ii) general principles of equity, regardless of whether asserted in a proceeding at equity or law, and may be limited by federal or state securities laws and public policy considerations in respect thereof.

5.12 The execution, delivery and performance of this Agreement and the Warrant by the Company and the consummation of the transactions contemplated hereby and thereby will not conflict with or result in a breach or violation of any of the terms or provisions of, or constitute a default under, any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which the Company is a party or by which the Company is bound or to which any of the property or assets of the Company is subject, nor will such actions result in any violation of the provisions of the charter or by-laws of the Company or any statute, law, rule or regulation or any judgment, order or decree of any court or governmental agency or body having jurisdiction over the Company or any of its properties or assets, except for such breach, violation or default that, individually or in the aggregate, would not reasonably be expected to have a Material Adverse Effect.

5.13 No consent, approval, authorization, filing with or order of or registration with, any court or governmental agency or body is required in connection with the transactions contemplated herein, except such as have been obtained or made under the Securities Act or the Exchange Act and such as may be required under the securities, or blue sky, laws of any jurisdiction in connection with the offer and sale of the Units by the Company in the manner contemplated herein and in the General Disclosure Package.

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5.14 The financial statements, together with the related notes and schedules, of the Company included in the General Disclosure Package, or the Registration Statement or incorporated by reference therein, as the case may be, present fairly the financial condition, results of operations and cash flows of the Company and its consolidated subsidiaries and other consolidated entities as of the dates and for the periods indicated, comply in all material respects with the Securities Act and the Rules and Regulations thereunder, and have been prepared in conformity with generally accepted accounting principles applied on a consistent basis throughout the periods involved. No other financial statements or supporting schedules or exhibits are required by the Securities Act or the Rules and Regulations thereunder to be included in the General Disclosure Package or the Registration Statement or incorporated by reference therein, as the case may be.

5.15 Except as set forth in the General Disclosure Package there is no legal or governmental proceeding pending to which the Company is a party or of which any property or assets of the Company is the subject which is required to be described in the General Disclosure Package and is not described therein, or which, individually or in the aggregate, if determined adversely to the Company, would have a Material Adverse Effect or would prevent or adversely affect the ability of the Company to perform its obligations under this Agreement; and to the best of the Company’s knowledge, no such proceedings are threatened or contemplated by governmental authorities or threatened by others.

5.16 The Company has made all filings, applications and submissions required by, and possesses all approvals, licenses, certificates, certifications, clearances, consents, exemptions, marks, notifications, orders, permits and other authorizations issued by, the appropriate federal, state or foreign regulatory authorities (including, without limitation, the Food and Drug Administration of the U.S. Department of Health and Human Services (the “FDA”), and any other foreign, federal, state or local government or regulatory authorities performing functions similar to those performed by the FDA) necessary to conduct its businesses (collectively, “Permits”), except for such Permits which the failure to obtain would not have a Material Adverse Effect (the “Immaterial Permits”), and is in compliance in all material respects with the terms and conditions of all such Permits other than the Immaterial Permits (the “Required Permits”); all of such Required Permits held by the Company are valid and in full force and effect; there is no pending or, to the Company’s knowledge, threatened action, suit, claim or proceeding which may cause any such Required Permit to be limited, revoked, cancelled, suspended, modified or not renewed and the Company has not received any notice of proceedings relating to the limitation, revocation, cancellation, suspension, modification or non-renewal of any such Required Permit which, individually or in the aggregate, if the subject of an unfavorable decision, ruling or finding, would have a Material Adverse Effect, whether or not arising from transactions in the ordinary course of business, except as set forth in or contemplated by the General Disclosure Package.

5.17 The Company’s collaboration agreement with LEO Pharma A/S (“LEO”), which provides LEO with exclusive rights for the commercialization of ATryn in Europe, the Middle East and Canada, remains in full force and effect.

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6. Survival of Representations, Warranties and Agreements. Notwithstanding any investigation made by any party to this Agreement or by the Placement Agents, all covenants, agreements, representations and warranties made by the Company and the Investor herein will survive after the Closing.

7. Additional Issuances of Securities.

7.1 For purposes of this Section 7, the following definitions shall apply.

(a) “Approved Stock Plan” means any employee benefit plan which has been approved by the Board of Directors of the Company, pursuant to which the Company’s securities may be issued to any employee, officer or director for services provided to the Company.

(b) “Common Stock Equivalents” means, collectively, Options and Convertible Securities.

(c) “Convertible Securities” means any stock or securities (other than Options) convertible into or exercisable or exchangeable for Common Stock.

(d) “Excluded Securities” means Common Stock issued or issuable: (i) as a stock dividend to holders of Common Stock or upon any subdivision or combination of shares of Common Stock; (ii) in connection with any Approved Stock Plan; (iii) any securities issued to the seller as consideration for the acquisition of another entity by the Company by merger or share exchange (whereby the Company owns no less than 51% of the voting power of the surviving entity) or purchase of substantially all of such entity’s stock or assets; (iv) any securities issued in connection with a license, strategic partnership, joint venture or other similar agreement, provided that the purpose of such arrangement is not primarily the raising of capital; (v) upon exercise of warrants issued as a part of the issuance of straight debt securities (with no equity or equity-linked feature) issued to a financial institution or lender in connection with a bank loan, credit, lease, or other debt transaction with such financial institution or lender (where warrant coverage is not greater than 5%); (vi) upon conversion of any Options or Convertible Securities which are outstanding on the day immediately preceding the Closing Date, provided that the terms of such Options or Convertible Securities are not amended, modified or changed on or after the Closing Date; or (vii) in the event participation may, in the sole discretion of counsel to the Company based upon the written advice of Nasdaq, result in aggregation for the purposes of the Nasdaq shareholder approval rules.

(e) “Options” means any rights, warrants or options to subscribe for or purchase Common Stock or Convertible Securities.

(f) “Trading Day” means any day on which the Common Stock is traded on the Nasdaq Global Market, or, if the Nasdaq Global Market is not the principal trading market for the Common Stock, then on the principal securities exchange or securities market on which the Common Stock is then traded; provided that “Trading Day” shall not include any day on which the Common Stock is scheduled to trade on such exchange or market for less than 4.5 hours or any day that the Common Stock is suspended from trading during the final hour of trading on such exchange or market (or if such exchange or market does not designate in advance the closing time of trading on such exchange or market, then during the hour ending at 4:00 p.m., New York City Time).

7.2 From the date hereof until the date that is six months after the Closing Date (the “Trigger Date”), the Company will not, directly or indirectly, offer, sell, grant any option to purchase, or otherwise dispose of (or announce any offer, sale, grant or any option to purchase or other disposition of) any of its or its subsidiaries’ equity or equity equivalent securities, including without limitation any debt, preferred stock or other instrument or security that is, at any time during its life and under any circumstances, convertible into or exchangeable or exercisable for shares of Common Stock or Common Stock Equivalents (any such offer, sale, grant, disposition or announcement being referred to as a “Subsequent Placement”).

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7.3 From the Trigger Date until the fifteen (15) month anniversary of the Closing Date, the Company will not, directly or indirectly, effect any Subsequent Placement unless the Company shall have first complied with this Section 7.3.

(a) The Company shall deliver to each Investor an irrevocable written notice (the ”Offer Notice”) of any proposed or intended issuance or sale or exchange (the ”Offer”) of the securities being offered (the “Offered Securities”) in a Subsequent Placement, which Offer Notice shall (w) identify and describe the Offered Securities, (x) describe the price and other terms upon which they are to be issued, sold or exchanged, and the number or amount of the Offered Securities to be issued, sold or exchanged, (y) identify the persons or entities (if known) to which or with which the Offered Securities are to be offered, issued, sold or exchanged and (z) offer to issue and sell to or exchange with such Investors 20% of the Offered Securities, allocated among such Investors (a) based on such Investor’s pro rata portion of Common Stock purchased hereunder (the “Basic Amount”), and (b) with respect to each Investor that elects to purchase its Basic Amount, any additional portion of the Offered Securities attributable to the Basic Amounts of other Investors as such Investor shall indicate it will purchase or acquire should the other Investors subscribe for less than their Basic Amounts (the “Undersubscription Amount”).

(b) To accept an Offer, in whole or in part, such Investor must deliver a written notice to the Company prior to the end of the tenth (10^th) Business Day after such Investor’s receipt of the Offer Notice (the “Offer Period”), setting forth the portion of such Investor’s Basic Amount that such Investor elects to purchase and, if such Investor shall elect to purchase all of its Basic Amount, the Undersubscription Amount, if any, that such Investor elects to purchase (in either case, the “Notice of Acceptance”). If the Basic Amounts subscribed for by all eligible Investors are less than the total of all of the Basic Amounts, then each Investor who has set forth an Undersubscription Amount in its Notice of Acceptance shall be entitled to purchase, in addition to the Basic Amounts subscribed for, the Undersubscription Amount it has subscribed for; provided, however, that if the Undersubscription Amounts subscribed for exceed the difference between the total of all the Basic Amounts and the Basic Amounts subscribed for (the “Available Undersubscription Amount”), each Investor who has subscribed for any Undersubscription Amount shall be entitled to purchase only that portion of the Available Undersubscription Amount as the Basic Amount of such Investor bears to the total Basic Amounts of all eligible Investors that have subscribed for Undersubscription Amounts, subject to rounding by the Company to the extent its deems reasonably necessary.

(c) The Company shall have ten (10) business days from the expiration of the Offer Period above to offer, issue, sell or exchange all or any part of such Offered Securities as to which a Notice of Acceptance has not been given by the eligible Investors (the “Refused Securities”), but only to the offerees described in the Offer Notice (if so described therein) and only upon terms and conditions (including, without limitation, unit prices and interest rates) that are not more favorable to the acquiring person or persons or less favorable to the Company than those set forth in the Offer Notice.

(d) In the event the Company shall propose to sell less than all the Refused Securities (any such sale to be in the manner and on the terms specified in Section 7.3(c) above), then each Investor may, at its sole option and in its sole discretion, reduce the number or amount of the Offered Securities specified in its Notice of Acceptance to an amount that shall be not less than the number or amount of the Offered Securities that such Investor elected to purchase pursuant to Section 7.3(b) above multiplied by a fraction, (i) the numerator of which shall be the number or amount of Offered Securities the Company actually proposes to issue, sell or exchange (including Offered Securities to be issued or sold to Investors pursuant to Section 7.3(c) above prior to such reduction) and (ii) the denominator of which shall be the original amount of the Offered Securities. In the event that any Investor so elects to reduce the number or amount of Offered Securities specified in its Notice of Acceptance, the Company may not issue, sell or exchange more than the reduced number or amount of the Offered Securities unless and until such securities have again been offered to the Investors in accordance with Section 7.3(a) above.

(e) Upon the closing of the issuance, sale or exchange of all or less than all of the Refused Securities, the Investors shall acquire from the Company, and the Company shall issue to the Investors, the number or amount of Offered Securities specified in the Notices of Acceptance, as reduced pursuant to Section 7.3(d) above if the Investors have so elected, upon the terms and conditions specified in the Offer. Notwithstanding anything to the contrary contained in this Agreement, if the Company does not consummate the closing of the issuance, sale or exchange of all or less than all of the Refused Securities within ten (10) business days of the expiration of the Offer Period, the Company shall issue to the Investors the number or amount of Offered Securities specified in the Notices of Acceptance, as reduced pursuant to Section 7.3(d) above if the Investors have so elected, upon the terms and conditions specified in the Offer. The purchase by the Investors of any Offered Securities is subject in all cases to the preparation, execution and delivery by the Company and the Investors of a purchase agreement relating to such Offered Securities reasonably satisfactory in form and substance to the Investors and their respective counsel.

(f) Any Offered Securities not acquired by the Investors or other persons in accordance with Section 7.3(c) above may not be issued, sold or exchanged until they are again offered to the eligible Investors under the procedures specified in this Agreement.

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7.4 The restrictions contained in Sections 7.2 and 7.3 shall not apply in connection with the issuance of any Excluded Securities.

7.5 Notwithstanding anything to the contrary contained in this Section 7, in connection with any Subsequent Placement involving a public offering, the Company shall deliver the Offer Notice to the Investors on the later of (i) five (5) business days prior to the proposed pricing of the Subsequent Financing or (ii) the commencement of marketing of the Subsequent Financing, but in no event less than one (1) business day prior to the proposed pricing date of the Subsequent Financing, and the Offer Notice shall only be required to provide the reasonably anticipated transaction terms (but not pricing) and description of the Offered Securities.

8. From the date hereof until the 6 month anniversary of the Closing Date, the Company shall not issue, sell or exchange, agree or obligate itself to issue, sell or exchange, or reserve or set aside for issuance, sale or exchange any (i) shares of Common Stock, (ii) any other equity security of the Company, including without limitation, preferred shares, (iii) any debt security of the Company which by its terms is convertible into or exchangeable for any equity security of the Company, (iv) any security of the Company that is a combination of debt and equity, or (v) any option, warrant or other right to subscribe for, purchase or otherwise acquire any such equity security or any such debt security of the Company. The forgoing not withstanding, this shall not apply to: (a) Common Stock issued as a stock dividend to holders of Common Stock or upon any subdivision or combination of shares of Common Stock; (b) any capital stock or derivative thereof granted to an employee, director or consultant under a Company stock or stock option plan or as compensation for services; (c) any securities issued as consideration for the acquisition of another entity by the Company by merger or share exchange (whereby the Company owns no less than 51% of the voting power of the surviving entity) or purchase of substantially all of such entity’s stock or assets; (d) any securities issued in connection with a license, strategic partnership, joint venture or other similar agreement, provided that the purpose of such arrangement is not primarily the raising of capital; (e) straight debt securities (with no equity or equity-linked feature) issued to a financial institution or lender in connection with a bank loan, credit, lease, or other debt transaction with such financial institution or lender (where warrant coverage is not greater than 5%); (f) securities issuable upon the exercise or conversion of securities outstanding on the Closing Date; or (g) any securities the issuance of which is approved by a majority of the Investors.

9. Notices. All notices, requests, consents and other communications hereunder will be in writing, will be mailed (a) if within the domestic United States by first-class registered or certified airmail, or nationally recognized overnight express courier, postage prepaid, or by facsimile or (b) if delivered from outside the United States, by International Federal Express or facsimile, and will be deemed given (i) if delivered by first-class registered or certified mail domestic, three business days after so mailed, (ii) if delivered by nationally recognized overnight carrier, one business day after so mailed, (iii) if delivered by International Federal Express, two business days after so mailed and (iv) if delivered by facsimile, upon electric confirmation of receipt and will be delivered and addressed as follows:

(a) if to the Company, to:

GTC Biotherapeutics, Inc.

175 Crossing Boulevard

Framingham, MA 01702

Attention: President

Phone: (508)  ###-###-####

Telecopy: (508)  ###-###-####

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with copies to:

Edwards Angell Palmer & Dodge LLP

111 Huntington Avenue

Boston, MA 02199

Attention: Nathaniel S. Gardiner, Esq.

Phone: (617)  ###-###-####

Telecopy: (617)  ###-###-####

(b) if to the Investor, at its address on the Signature Page hereto, or at such other address or addresses as may have been furnished to the Company in writing.

10. Changes. This Agreement may not be modified or amended except pursuant to an instrument in writing signed by the Company and the Investor.

11. Headings. The headings of the various sections of this Agreement have been inserted for convenience of reference only and will not be deemed to be part of this Agreement.

12. Severability. In case any provision contained in this Agreement should be invalid, illegal or unenforceable in any respect, the validity, legality and enforceability of the remaining provisions contained herein will not in any way be affected or impaired thereby.

13. Governing Law. This Agreement will be governed by, and construed in accordance with, the internal laws of the State of New York, without giving effect to the principles of conflicts of law that would require the application of the laws of any other jurisdiction.

14. Counterparts. This Agreement may be executed in two or more counterparts, each of which will constitute an original, but all of which, when taken together, will constitute but one instrument, and will become effective when one or more counterparts have been signed by each party hereto and delivered to the other parties. The Company and the Investor acknowledge and agree that the Company shall deliver its counterpart to the Investor along with the Prospectus (or if no physical Prospectus is delivered, when an electronic version of the Prospectus is available to the Investor).

15. Confirmation of Sale. The Investor acknowledges and agrees that such Investor’s receipt of the Company’s counterpart to this Agreement, together with the Prospectus (or if the Prospectus is otherwise made available to the Investor), shall constitute written confirmation of the Company’s sale of Shares to such Investor.

16. Termination. In the event that the Placement Agreement is terminated by the Placement Agents pursuant to the terms thereof, this Agreement shall terminate without any further action on the part of the parties hereto.

The Company has filed a registration statement (Registration No. 333-135054, including a base prospectus) with the SEC for the offering to which this communication relates. Before you invest, you should read the base prospectus in that registration statement and other documents the Company has filed with the SEC for more complete information about the Company and this offering. You may get these documents for free by visiting EDGAR on the SEC Web site at www.sec.gov. Alternatively, the Company or any placement agent participating in the offering will arrange to send you the Base Prospectus if you request it by calling (212)  ###-###-####.

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EXHIBIT A

FORM OF WARRANT

[See Exhibit 4.1 hereto]

EXHIBIT B

GTC BIOTHERAPEUTICS, INC.

INVESTOR QUESTIONNAIRE

Pursuant to Section 3 of Annex I to the Agreement, please provide us with the following information: