Robbins Geller Rudman & Dowd LLP announced that a class action has been commenced in the United States District Court for the District of Colorado on behalf of a proposed class of Allos Therapeutics, Inc. shareholders who held Allos common stock during the period beginning July 20, 2011 through and including the closing of the proposed acquisition of Allos by AMAG Pharmaceuticals, Inc.

If you wish to serve as lead plaintiff, you must move the Court no later than 60 days from today. If you wish to discuss this action or have any questions concerning this notice or your rights or interests, please contact plaintiffs’ counsel, Darren Robbins of Robbins Geller at 800/449-4900 or 619/231-1058, or via e-mail at djr@rgrdlaw.com. If you are a member of this class, you can view a copy of the complaint as filed or join this class action online at http://www.rgrdlaw.com/cases/allostherapeutics. Any member of the putative class may move the Court to serve as lead plaintiff through counsel of their choice, or may choose to do nothing and remain an absent class member.

The complaint charges Allos and its Board of Directors (the “Board”) with breaches of fiduciary duty and aiding and abetting breaches of fiduciary duty under state law and the Board and AMAG with violations of the Securities Exchange Act of 1934 (“1934 Act”). Allos is a biopharmaceutical company that engages in the development and commercialization of anti-cancer therapeutics.

The action arises from Allos and AMAG’s July 20, 2011 announcement that Allos had entered into a definitive merger agreement (the “Merger Agreement”) under which Allos would be acquired by AMAG in a transaction valued at approximately $260 million (the “Proposed Acquisition”). Under the terms of the Merger Agreement, Allos stockholders will receive a fixed ratio of 0.1282 shares of AMAG common stock for each share of Allos common stock held. The deal values Allos stock at $2.44 a share using AMAG’s prior closing price of $19.07. The complaint alleges that the Proposed Acquisition significantly undervalues Allos, as Allos shares traded as high as $4.21 as recently as January 12, 2011, and after the announcement of the Proposed Acquisition the price of AMAG common stock has fallen to $13.58 per share, giving the deal a real value of just $1.74 per Allos share.

The complaint further alleges that in an attempt to secure shareholder support for the Proposed Acquisition, on August 22, 2011, defendants issued a materially false and misleading Preliminary Joint Proxy/Prospectus on Form S-4 (the “Proxy”). The Proxy, which recommends that Allos shareholders vote in favor of the Proposed Acquisition, omits and/or misrepresents material information about the unfair sales process for the Company, conflicts of interest that corrupted the sales process, the unfair consideration offered in the Proposed Acquisition, and the actual intrinsic value of the Company on a stand-alone basis and as a merger partner for AMAG, in contravention of §§14(a) and 20(a) of the 1934 Act and/or defendants’ fiduciary duty of disclosure under state law.

Plaintiffs seek injunctive relief on behalf of all shareholders of Allos who held Allos common stock during the period beginning July 20, 2011 through and including the closing of the proposed acquisition of Allos by AMAG (the “Class”). The plaintiffs are represented by Robbins Geller, which has expertise in prosecuting investor class actions and extensive experience in actions involving financial fraud.

Robbins Geller, a 180-lawyer firm with offices in San Diego, San Francisco, New York, Boca Raton, Washington, D.C., Philadelphia and Atlanta, is active in major litigations pending in federal and state courts throughout the United States and has taken a leading role in many important actions on behalf of defrauded investors, consumers, and companies, as well as victims of human rights violations. The Robbins Geller Web site (http://www.rgrdlaw.com) has more information about the firm.