Callisto Pharmaceuticals Announces Dr. Moshe Talpaz to Join Scientific Advisory Board.

Business Editors/Health/Medical Writers

NEW YORK--(BUSINESS WIRE)--Oct. 21, 2003

Callisto Pharmaceuticals, Inc. (OTCBB: CLSP) announced that Dr. Moshe Talpaz, Chairman of the Department of Bioimmunotherapy of The University of Texas M. D. Anderson Cancer Center has become a member of Callisto's Scientific Advisory Board.

Dr. Talpaz, well known for his role in the clinical development of Gleevec, is an internationally-recognized authority on leukemia and blood cancers. Dr. Talpaz continues to be involved in the clinical development of numerous cancer drugs, and has been a pioneer in developing currently accepted treatment protocols especially in the leukemia area. "I am pleased to be working with Callisto on the clinical development of Atiprimod which represents a new non-classical therapeutic approach to the treatment of multiple myeloma. This drug tackles key cellular signals that drive this terrible disease" says Dr. Talpaz. "We at Callisto are delighted to have someone of Dr. Talpaz's experience and stature on our Scientific Advisory Board. Dr. Talpaz brings a world of knowledge in designing and running clinical trials, something that will be pivotal to us as we move forward with our lead drug candidate, Atiprimod, into the clinic." says Dr. Gary S. Jacob, CEO of Callisto Pharmaceuticals, Inc.

About Callisto Pharmaceuticals, Inc.

Callisto is a biopharmaceutical company primarily focused on the development of drugs to treat multiple myeloma, other cancers and osteolytic bone disease. Callisto's lead drug candidate, Atiprimod, is a small-molecule, orally available drug with antiproliferative and antiangiogenic activity. Atiprimod successfully completed Phase I clinical trials in rheumatoid arthritis patients and Callisto filed an IND on September 23, 2003 with the U.S. Food and Drug Administration on Atiprimod to enter a Phase I/IIa clinical trial in multiple myeloma patients. The drug is also being explored as an agent to treat osteolytic bone disease. In addition, Callisto has programs focused on the development of an analog of the human intestinal hormone, uroguanylin, to treat colon cancer, and drugs to protect against staphylococcal and streptococcal bioweapons, as a protection against the devastating effects of toxic shock syndrome. Callisto has two operating subsidiaries, Callisto Research Labs, LLC and Synergy Pharmaceuticals Inc.

Included in this release are "forward-looking: statements. Such statements are indicated by words such as "expect," "should," "anticipate" and similar words indicating uncertainty in facts and figures. Although Callisto believes that the expectations reflected in such forward-looking statements are reasonable, it can give no assurance that such expectations reflected in such forward-looking statements will prove to have been correct. Callisto's actual results could differ materially from those anticipated in the forward-looking statements as a result of various factors.