Pursuant to 17 CFR 240.24b-2, confidential information has been omitted in places marked [* * *] and has been filed separately with the Securities and Exchange Commission pursuant to a ConfidentialTreatment Application filed with the Commission.

Exhibit 10.39

Pursuant to 17 CFR 240.24b-2, confidential information has been omitted in places marked “[* * *]” and has been filed separately with the Securities and Exchange Commission pursuant to a Confidential Treatment Application filed with the Commission.

EXECUTION COPY

FIRST AMENDMENT TO THE DEVELOPMENT AND MARKETING AGREEMENT

This First Amendment (“Amendment”) to the Development and Marketing Agreement (“Agreement”) dated February 22, 2006, by and between Spectrum Pharmaceuticals, Inc. (“Spectrum”) and Par Pharmaceutical, Inc. (“Par”) is entered into and is effective as of November 10, 2006 (“First Amendment Effective Date”), hereinafter referred to as “Party” and, collectively, as “Parties.” Capitalized terms used but not defined herein shall have the meanings given them in the Agreement.

WHEREAS, on November 10, 2006, the Parties each hereby give their consent to Spectrum entering into, and Spectrum is entering into a Settlement Agreement, dated November 10, 2006 (the “Settlement Agreement”), with Glaxo Group Limited (“GSK”) to settle the Sumatriptan Litigation. Pursuant to the Settlement Agreement, Spectrum received the right to sell Spectrum Generic Sumatriptan Products and GSK Supplied Products (both as defined in the Settlement Agreement and the Supply and Distribution Agreement) in accordance with the terms of the Settlement Agreement;

WHEREAS, pursuant to the Settlement Agreement, Spectrum and Par hereby consent to, and GSK and Glaxo Wellcome Manufacturing PTE Limited and Par are entering into a Supply and Distribution Agreement, dated November 10, 2006 (the “Supply and Distribution Agreement”)(the Settlement Agreement and the Supply and Distribution Agreement are collectively referred to herein as the “GSK Agreements”) pursuant to which GSK agrees to supply the GSK Supplied Products to Par for distribution. Par agrees to purchase and distribute GSK Supplied Products on behalf of Spectrum in order to fulfill its obligations under the Agreement;

WHEREAS, the Parties wish the Agreement to apply only to GSK Supplied Products and the Spectrum Generic Sumatriptan Products, as defined in the GSK Agreements (collectively, the “GSK Sumatriptan Products”); and

WHEREAS, the Parties wish to amend certain terms of the Agreement to reflect the Settlement Agreement and Supply and Distribution Agreement and the elimination from the Agreement of all Products except the GSK Sumatriptan Products, among other changes, as set forth below.

NOW, THEREFORE, in consideration of the mutual covenants, promises and agreements set forth herein, the Parties hereby agree as follows:

Pursuant to 17 CFR 240.24b-2, confidential information has been omitted in places marked “[* * *]” and has been filed separately with the Securities and Exchange Commission pursuant to a Confidential Treatment Application filed with the Commission.

EXECUTION COPY

Pursuant to 17 CFR 240.24b-2, confidential information has been omitted in places marked “[* * *]” and has been filed separately with the Securities and Exchange Commission pursuant to a Confidential Treatment Application filed with the Commission.

EXECUTION COPY

“‘Products’ means GSK Sumatriptan Products and the products listed on Schedule 1.33, except for the injectable [* * *] presentation listed on Schedule 1.33 unless the Settlement Agreement and the Supply and Distribution Agreement are terminated in which case the injectable [* * *] presentation will be included.’”

“Territory” shall mean the United States of America (including the Commonwealth of Puerto Rico) its possessions and territories and U.S. military or U.S. government installations that are under the purview of the FDA.

“Product Claims” shall have the meaning given such term in the Supply and Distribution Agreement.

Pursuant to 17 CFR 240.24b-2, confidential information has been omitted in places marked “[* * *]” and has been filed separately with the Securities and Exchange Commission pursuant to a Confidential Treatment Application filed with the Commission.

EXECUTION COPY

License Grant. Spectrum hereby grants to Par an exclusive (even as to Spectrum) royalty free (other than as set forth in Article 7), irrevocable (subject to Article 14) license to market, promote, distribute, sell and have sold the Products in the Territory. To the extent permitted by the Supply and Distribution Agreement, the foregoing license shall include the right for Par to grant sublicenses and appoint sub-contractors to market, distribute and sell the Products within the Territory on Par’s behalf.

Notwithstanding the foregoing, where applicable, the Commercial Launch of the Product, and Par’s obligations in regard to such Commercial Launch, shall be subject to the applicable provisions set forth in the Supply and Distribution Agreement and the Settlement Agreement.

Notwithstanding the foregoing, recalls of the Product, and Par’s obligations in regard to such Recalls, shall be subject to Section 5.8(b) of the Supply and Distribution Agreement, as applicable. Without limiting the foregoing, Par shall promptly notify Spectrum of any Recalls which it may be necessary to conduct and consult with Spectrum as to how best to proceed.

Par shall permit Spectrum’s quality assurance representatives to inspect the manufacturing, distribution and storage facilities and all books and records of

Pursuant to 17 CFR 240.24b-2, confidential information has been omitted in places marked “[* * *]” and has been filed separately with the Securities and Exchange Commission pursuant to a Confidential Treatment Application filed with the Commission.

EXECUTION COPY

Par relating to the production of the Product at all times upon thirty (30) days prior written notice, during normal business hours and on a confidential basis; provided, however, that such inspections shall be limited to twice annually in the absence of a breach of this Agreement by Par. The foregoing obligation shall not apply with regard to GSK or GSK Supplied Products. Par will use commercially reasonable efforts to include Spectrum in any inspections of GSK facilities in connection with GSK Supplied Product, and if Par is unable to do so will provide a written report regarding the same to Spectrum.

Any intellectual property rights (including patents, patent applications, know-how, trade secrets, copyrights, trade dress, housemarks and trademarks) owned by either Party or its Affiliates prior to the Effective Date shall remain solely owned by such Party (or its Affiliates, as applicable). Each of the Parties shall not during the Term, or at any time thereafter, represent or assert that it is the owner of any such intellectual property rights of the other Party (or its Affiliates), whether or not such rights are registered. The Parties do not contemplate that any development activities will be performed under this Agreement, but in the event that any such activities should be conducted under this Agreement the intellectual property laws of the United States and the State of New York will govern the allocation of intellectual property rights among the Parties in any developments resulting from such activities.

“Notwithstanding the foregoing, Par shall have the right to disclose Confidential Information of Spectrum that it acquires under this Agreement to GSK, but only to the extent necessary for Par to comply with its obligations under the Supply and Distribution Agreement and only after receipt of prior written consent from Spectrum.”

Pursuant to 17 CFR 240.24b-2, confidential information has been omitted in places marked “[* * *]” and has been filed separately with the Securities and Exchange Commission pursuant to a Confidential Treatment Application filed with the Commission.

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“, except as may be set forth in the Settlement Agreement or Supply and Distribution Agreement” after “to any royalties or fees”.

First, move “, (i)” after “arising out of.”

Second, after “obligation of Par under this Agreement” add “or under the Supply and Distribution Agreement”

Third, strike “or” before “(iii).”

Fourth, add at the end of the paragraph: “or (iv) any Product Claims (as defined in the Supply and Distribution Agreement).”

12.6 “Indemnification Obligation for GSK Supplied Product.” With respect to any Product Claims or claims for indemnification by GSK under the Supply and Distribution Agreement, the obligation in respect of such claims shall [* * *].

“Notwithstanding the foregoing, Spectrum may assign, sell, transfer or otherwise convey its right to receive its share of the Net Profit under Section 7.1 of this Agreement to a Third Party.”

“, and the Settlement Agreement and the Supply and Distribution Agreement,” after “Confidentiality Agreement”.

Pursuant to 17 CFR 240.24b-2, confidential information has been omitted in places marked “[* * *]” and has been filed separately with the Securities and Exchange Commission pursuant to a Confidential Treatment Application filed with the Commission.

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[***]. In the event that there is a [***], Spectrum may [***], all [***] from the date [***] accordance with an [***] mutually agreed to by and among [***] shall also include [***].

GSK Agreement: In the event that Par recovers any damages, including [* * *], under the Supply and Distribution Agreement Par shall pay Spectrum [* * *] percent ([* * *]%) of such damages within [* * *] ([* * *]) days after recovering them.

Pursuant to 17 CFR 240.24b-2, confidential information has been omitted in places marked “[* * *]” and has been filed separately with the Securities and Exchange Commission pursuant to a Confidential Treatment Application filed with the Commission.

EXECUTION COPY

All amounts paid to GSK under the GSK agreements shall be included in the calculation of Net Profits.

51. Consistent with the representations, warranties and covenants made in this Amendment, the Settlement Agreement, the Supply & Distribution Agreement and the Stipulation of Dismissal, as of the Execution Date, Spectrum and each of its respective predecessors, successors, parents, subsidiaries, Affiliates, divisions, general partners, limited partners, and assigns (collectively, the “Spectrum Releasees”), fully, finally and forever release, relinquish, acquit, and discharge Par and each of its respective predecessors, successors, parents, subsidiaries, Affiliates, divisions, general partners, limited partners, and assigns, (collectively, the “Par Releasees”) of and from, and covenant not to sue, not to assign to any other entity a right to sue, and not to authorize any other entity to sue, any Par Releasee for, any and all claims, counterclaims, defenses, demands, causes of action, suits, damages, debts, liabilities, obligations, rights, and set-offs of any and all kind or description whatsoever, including costs, expenses, and attorneys’ fees (collectively, “Losses”), known or unknown, suspected or unsuspected, asserted or unasserted, in law or equity, on which no judgment has yet been rendered, from the beginning of the world to the Execution Date that could have been, are or could be asserted in connection with the obligations of the parties under the Agreement through the date of this Amendment, and in connection with the entering into of the GSK Agreements by either Party or that arise out of any claim, counterclaim, affirmative defense, act, transaction, series of transactions, fact, omission, or matter that could have been, is or was the subject matter of the District Court Case (collectively, “Acts”). Consistent with the representations, warranties and covenants made in this Amendment, the Settlement Agreement, the Supply & Distribution Agreement and the Stipulation of Dismissal, as of the Execution Date, Par and each of the other Par Releasees, fully, finally and forever release, relinquish, acquit, and discharge the Spectrum Releasees of and from, and covenant not to sue, not to assign to any other entity a right to sue, and not to authorize any other entity to sue, any Spectrum Releasee for, any and all Losses, known or unknown, suspected or unsuspected, asserted or unasserted, in law or equity, on which no judgment has yet been rendered, from the beginning of the world to the Execution Date that could have been, are or were asserted in the District Court Case, or that arise out of any Acts.

Except as provided herein, all other terms and conditions of the Agreement shall remain in full force and effect.

[Signature page to follow]

Pursuant to 17 CFR 240.24b-2, confidential information has been omitted in places marked “[* * *]” and has been filed separately with the Securities and Exchange Commission pursuant to a Confidential Treatment Application filed with the Commission.

EXECUTION COPY

[Signature Page to First Amendment to Development and Marketing Agreement]

IN WITNESS WHEREOF, the Parties hereto have executed this First Amendment to the Development and Marketing Agreement to be effective as of the First Amendment Effective Date.

SPECTRUM PHARMACEUTICALS, INC.

PAR PHARMACEUTICAL, INC.

Pursuant to 17 CFR 240.24b-2, confidential information has been omitted in places marked “[* * *]” and has been filed separately with the Securities and Exchange Commission pursuant to a Confidential Treatment Application filed with the Commission.

EXECUTION COPY

Schedule 1.33