ALTH Allos Therapeutics, Inc. (MM)

Allos Therapeutics, Inc. (Nasdaq: ALTH) today announced that the Company will present data from an in vitro study examining the potency of pralatrexate in colon, breast, ovarian, lung, prostate, and head and neck cancer cell lines at the upcoming American Association for Cancer Research 100th Annual Meeting to be held in Denver, CO on April 18 - 22.

Presentation details are as follows: � Date/Time: Sunday, April 19, 2009, 1- 5 p.m. (Mountain) Session: Experimental and Molecular Therapeutics 5 Poster Title: Cytotoxicity of Pralatrexate, a Novel Synthetic Antifolate, in Human Cancer Cell Lines Abstract Number: 1686 Location: Hall B-F, Poster Section 33, Poster Number 6

About Pralatrexate

Pralatrexate is a novel targeted antifolate designed to accumulate preferentially in cancer cells. Based on preclinical studies, the Company believes that pralatrexate selectively enters cells expressing RFC-1, a protein that is over expressed on cancer cells compared to normal cells. Once inside cancer cells, pralatrexate is efficiently polyglutamylated, which leads to high intracellular drug retention. Polyglutamylated pralatrexate essentially becomes �trapped� inside cancer cells, making it less susceptible to efflux-based drug resistance. Acting on the folate pathway, pralatrexate interferes with DNA synthesis and triggers cancer cell death. The Company believes pralatrexate has the potential to be delivered as a single agent or in combination therapy regimens.

About Allos Therapeutics, Inc.

Allos Therapeutics is a biopharmaceutical company focused on developing and commercializing innovative small molecule drugs for the treatment of cancer. The Company�s lead product candidate, pralatrexate, is a novel targeted antifolate designed to accumulate preferentially in cancer cells. In February 2009, the Company announced the final results from PROPEL, the Company�s pivotal Phase 2 (PROPEL) trial of pralatrexate in patients with relapsed or refractory peripheral T-cell lymphoma (PTCL). The PROPEL trial was conducted under an agreement reached with the U.S. Food and Drug Administration under its special protocol assessment (SPA) process. Based on the results of the PROPEL trial, the Company submitted a New Drug Application to the U.S. Food and Drug Administration for pralatrexate for the treatment of relapsed or refractory PTCL in March 2009. The Company is also investigating pralatrexate in patients with non-small cell lung cancer, bladder cancer and a range of lymphoma sub-types. The Company currently retains exclusive worldwide rights to pralatrexate for all indications. For additional information, please visit www.allos.com.

Safe Harbor Statement

The anticipated presentation will contain forward-looking statements that involve significant risks and uncertainties. Additional information concerning these forward-looking statements and other factors that may cause actual results to differ materially from those anticipated in the forward-looking statements is contained in the "Risk Factors" section of the Company's Annual Report on Form 10-K for the year ended December 31, 2008 and in the Company's other periodic reports and filings with the Securities and Exchange Commission. The Company cautions investors not to place undue reliance on the forward-looking statements contained in the presentation. All forward-looking statements are based on information currently available to the Company on the date thereof, and the Company undertakes no obligation to revise or update these forward-looking statements to reflect events or circumstances after the date of this presentation, except as required by law.