ANX Mast Therapeutics, Inc.

ADVENTRX Pharmaceuticals, Inc. (AMEX:ANX) today announced that it has completed approximately 25% of the planned enrollment in its European Union (EU)-based CoFactor(TM) Phase IIb clinical trial for the treatment of metastatic colorectal cancer. The Company began dosing patients in this trial in May 2005. CoFactor is ADVENTRX's biomodulator designed to enhance the effects and reduce associated toxicity of the widely used cancer drug, 5-fluorouracil (5-FU). The Phase IIb clinical trial is a multi-center, open label, randomized study to evaluate the safety and efficacy of CoFactor and 5-FU versus leucovorin and 5-FU in first-line treatment for metastatic colorectal cancer. Approximately 300 patients in this study will be randomized to receive either CoFactor plus 5-FU, or leucovorin plus 5-FU. To date 21 clinical sites have been opened for patient enrollment in the United Kingdom, India, Serbia, Poland and Romania. The Company plans to open an additional nine clinical sites for patient enrollment by the end of October 2005. "We are delighted by the rate of patient enrollment in this trial, which has so far exceeded our expectations," said Evan M. Levine, president and CEO of ADVENTRX Pharmaceuticals. "We believe this trial will further establish CoFactor's favorable safety and efficacy profile in a direct comparison to leucovorin. As we continue to move our CoFactor clinical programs forward, we remain confident in our ability to achieve our goal of commercialization." ADVENTRX is also completing its US-based Phase II CoFactor trial (COFU) in metastatic colorectal cancer and expects to report follow-up study data, including a third-party assessment of efficacy data, from this trial in the first quarter of 2006. Additionally, the Company is currently recruiting clinical sites for a US-based pivotal Phase III trial in the same indication, and plans to begin dosing patients in the first quarter of 2006. About CoFactor CoFactor (ANX-510) is a folate-based biomodulator drug developed to enhance the activity and reduce associated toxicity of the widely used cancer chemotherapeutic 5-FU. In comparison to leucovorin, CoFactor creates more stable binding of the active form of 5-FU, FdUMP, to the target enzyme, thymidylate synthase (TS). CoFactor bypasses the chemical pathway required by leucovorin to deliver the active form of folate, allowing 5-FU to work more effectively. This improves 5-FU performance and lowers toxicity. More information on CoFactor can be found at http://www.adventrx.com/products/antic_cofactor.htm. About ADVENTRX ADVENTRX Pharmaceuticals is a biopharmaceutical research and development company focused on introducing new technologies for anticancer and antiviral treatments that improve the performance and safety of existing drugs, by addressing significant problems such as drug metabolism, toxicity, bioavailability and resistance. More information can be found on the Company's Web site at www.adventrx.com. Forward-Looking Statement This press release contains forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. Such statements are made based on management's current expectations and beliefs. Actual results may vary from those currently anticipated based upon a number of factors, including uncertainties inherent in the drug development process, the timing and success of clinical trials, the validity of research results, and the receipt of necessary approvals from the US Food and Drug Administration (FDA) and other regulatory agencies. For a discussion of such risks and uncertainties, which could cause actual results to differ from those contained in the forward-looking statements, see "Risk Factors" in the Company's last quarterly report on Form 10-Q, as well as other reports that the Company files from time to time with the Securities and Exchange Commission. All forward-looking statements are qualified in their entirety by this cautionary statement. The Company undertakes no obligation to release publicly any revisions, which may be made to reflect events or circumstances after the date hereof.