Agreement and Plan of Merger

On January 25, 2012, Micromet, Inc., a Delaware corporation ("Micromet"), entered into an Agreement and Plan of Merger (the "Merger Agreement") with Amgen Inc., a Delaware corporation ("Amgen") and Armstrong Acquisition, Corp., a Delaware corporation and a wholly owned subsidiary of Amgen ("Purchaser"). The board of directors of Micromet has unanimously (i) determined that the Merger Agreement and the transactions contemplated by the Merger Agreement are advisable, fair to, and in the best interests of Micromet and its stockholders,
(ii) approved and declared advisable the Merger Agreement, the Offer (as defined below), the Merger (as defined below) and the transactions contemplated thereby in accordance with the requirements of Delaware law and (iii) resolved to recommend that the stockholders of Micromet accept the Offer and tender their shares to Purchaser pursuant to the Offer (as defined below), and, to the extent required under applicable law, adopt the Merger Agreement.

Pursuant to the terms of the Merger Agreement, and on the terms and subject to the conditions thereof, among other things, Purchaser will commence a cash tender offer (the "Offer") to acquire all of the outstanding shares of common stock of Micromet, par value $0.00004 per share (together with the associated preferred share purchase rights, the "Shares"), at a price of $11.00 per share in cash (the "Offer Price"), without interest and less any required withholding taxes.

Purchaser's obligation to accept for payment and pay for Shares tendered in the Offer is subject to certain conditions, including, among other things, (i) that there shall not have been validly tendered and not validly withdrawn prior to the expiration date of the Offer that number of Shares that, when added to the Shares then beneficially owned by Amgen and its Subsidiaries, would represent one Share more than one-half (1/2) of the sum of (a) all Shares then outstanding plus (b) all Shares issuable upon the exercise, conversion or exchange of any options, warrants or other rights to acquire Shares then outstanding (other than any Shares issuable pursuant to the Top-Up Option, as defined below) regardless of whether or not then vested (the "Minimum Condition") and (ii) the expiration or termination of any applicable waiting period under any applicable antitrust law, including the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended. The consummation of the Offer is not subject to any financing condition.

Following the completion of the Offer and subject to the satisfaction or waiver of certain conditions set forth in the Merger Agreement, including, if required, receipt of approval by the stockholders of Micromet, Purchaser will merge with and into Micromet, with Micromet surviving as a wholly owned subsidiary of Amgen (the "Merger"). At the effective time of the Merger (the "Effective Time"), the Shares not purchased pursuant to the Offer (other than shares held by Micromet, Amgen, Purchaser, any subsidiary of Amgen or by stockholders of Micromet who have perfected their statutory rights of appraisal under Delaware law) will be converted into the right to receive an amount in cash equal to the Offer Price, without interest, and less any required withholding taxes. At the Effective Time, each outstanding option to purchase Shares issued pursuant to Micromet's equity incentive plans (collectively, the "Options") that is vested will be cashed out for the spread between the Offer Price and the exercise price of the applicable Option. At the Effective Time, each unvested Option will continue to vest in accordance with the existing vesting schedule (subject to a pro rata adjustment to the vesting schedules for partially accelerated vested options) and continued employment requirements, and such Options will cashed out as they vest based on the spread between the Offer Price and the exercise price of such unvested Option. All Options that are still unvested as of December 15, 2012 will vest as of that date and will be cashed out based on the spread between the Offer Price and the exercise price or the applicable Option. Options held by non-employee members of the board of directors of Micromet will be

Pursuant to the Merger Agreement, Micromet granted to Amgen and Purchaser an option (the "Top-Up Option") to purchase from Micromet, at a price per Share equal to the Offer Price, the number of newly-issued Shares equal to the lesser of (i) the number of Shares that, when added to the number of Shares owned by Amgen and its subsidiaries at the time of exercise of the Top-Up Option, constitutes one Share more than 90% of the number of Shares that would be outstanding immediately after the issuance of all Shares subject to the Top-Up Option on a fully diluted basis or (ii) the aggregate number of Shares that Micromet is authorized to issue under its certificate of incorporation but that are not issued and outstanding (and are not subscribed for or otherwise committed to be issued) at the time of exercise of the Top-Up Option; provided, however, that the Top-Up Option will not be exercisable unless immediately after such exercise and the issuance of Shares, Amgen and Purchaser will hold, in the aggregate, one Share more than 90% of the then outstanding Shares.

Following the completion of the Offer, if Parent and Purchaser own at least 90% of the then-outstanding Shares, the Merger will be consummated pursuant to the short-form merger procedures under Section 253 of the Delaware General Corporation Law. Following the completion of the Offer, if Parent and Purchaser hold less than 90% of the Shares then outstanding then the stockholders of Micromet holding a majority of the outstanding Shares must approve the Merger and adopt the Merger Agreement prior to consummating the Merger. In this event, Micromet has agreed to call and convene a stockholder meeting to obtain such approval.

The Merger Agreement includes representations and warranties and covenants of the parties customary for a transaction of this nature. Until the earlier of the termination of the Merger Agreement and the Effective Time, Micromet has agreed to operate its business and the business of its subsidiaries in the ordinary course and has agreed to certain other operating covenants, as set forth more fully in the Merger Agreement. Micromet has also agreed not to solicit or initiate discussions with any third party regarding acquisition proposals, which include potential licensing and collaboration transactions with Micromet.

. . .

As described above, Micromet and AST have entered into the Rights Amendment. The material terms of this transaction are described in Item 1.01, under the heading of "Amendment to Rights Agreement" above and are incorporated herein by reference.

As described above, Micromet, Amgen and each of Dr. Fagerberg and Dr. Baeuerle have entered into an Employment Amendment. The material terms of these transactions are described in Item 1.01, under the heading of "Amendment to Employment Agreements" above and are incorporated herein by reference.

On January 26, 2012, Micromet and Amgen issued a joint press release announcing the execution of the Merger Agreement. A copy of the press release was previously furnished by Micromet on a Schedule 14D-9C, filed with the SEC on January 26, 2012, and is hereby incorporated by reference.

(d) Exhibits

 2.1    Agreement and Plan of Merger, dated as of January 25, 2012, by and among
        Micromet, Inc., Amgen Inc. and Armstrong Acquisition Corp.*

 2.2    Form of Tender and Support Agreement, dated January 25, 2012, by and among
        Amgen Inc., Armstrong Acquisition Corp. and certain stockholders of
        Micromet, Inc.

 4.1    Second Amendment to Rights Agreement, dated as of January 25, 2012, by and
        between Micromet, Inc. and American Stock Transfer & Trust Company, LLC.

10.1    Amendment to Executive Employment Agreement, dated as of January 25, 2012,
        by and among Micromet, Inc., Amgen Inc. and Dr. Jan Fagerberg.

10.2    Amendment to Executive Employment Agreement, dated as of January 25, 2012,
        by and among Micromet, Inc., Amgen Inc. and Prof. Dr. Patrick A. Baeuerle.

99.1    Press Release issued January 25, 2012 (incorporated by reference to the
        Schedule 14D-9C filed by Micromet, Inc. on January 25, 2012).

* Schedules omitted pursuant to Item 601(b)(2) of Regulation S-K. Micromet agrees to furnish supplementally a copy of such schedules, or any section thereof, to the SEC upon request.

Important Information and Where To Find It

The Offer described in this communication has not yet commenced, and this communication is neither an offer to purchase nor a solicitation of an offer to sell any shares of the common stock of Micromet or any other securities. On the commencement date of the Offer, a tender offer statement on Schedule TO, including an offer to purchase, a letter of transmittal and related documents, will be filed with the United States Securities and Exchange Commission ("SEC"). The offer to purchase shares of

Safe Harbor for Forward-Looking Statements

Statements in this report that relate to future results and events are forward-looking statements based on Micromet's current expectations regarding the Offer and other transactions contemplated by the Merger Agreement. Actual results and events in future periods may differ materially from those expressed or implied by these forward-looking statements because of a number of risks, uncertainties and other factors. There can be no assurances that a transaction will be consummated. Other risks, uncertainties and assumptions include the risk that Micromet may not satisfy one or more closing conditions, including because a material adverse event outside the control of Micromet occurs; that the Merger Agreement may be terminated; the impact of the current economic environment; risks related to Micromet's ongoing development activities and clinical trials; and other risks that are described in Micromet's most recent Form 10-Q for the quarter ended September 30, 2011. Micromet undertakes no obligation to update these forward-looking statements except to the extent otherwise required by law.