Callisto Pharmaceuticals Announces New Clinical Trial of Atiprimod in Patients with Advanced Cancer

NEW YORK, NY – March 15, 2005 – Callisto Pharmaceuticals, Inc. (AMEX: KAL), a biopharmaceutical company primarily focused on the development of drugs to treat cancer and osteolytic bone disease, announced today a second clinical trial of Atiprimod, its lead drug presently in a Phase I/IIa trial in relapsed multiple myeloma patients.

The new trial entitled: "An Open Label Study of the Safety and Efficacy of Atiprimod Treatment for Patients with Advanced Cancer" is designed to assist in finding the maximum tolerated dose (MTD) of Atiprimod in advanced cancer patients and to assess the drug’s activity in solid tumors and hematologic malignancies. The trial protocol received IRB approval on Feb. 22, 2005 at the University of Texas M. D. Anderson Cancer Center with Dr. Razelle Kurzrock as the Principal Investigator. Site initiation was completed on March 3, 2005, and patient screening and dosing is anticipated to begin this month.

"We are pleased to see Atiprimod move forward into this trial in advanced cancer patients," said Dr. Donald Picker, Executive Vice President, Research and Development. "The trial will enable us to evaluate Atiprimod’s safety profile in a second cohort of cancer patients, providing additional clinical information and an expanded patient base."


About Callisto Pharmaceuticals, Inc.

Callisto is a biopharmaceutical company focused on the development of drugs to treat cancer and osteolytic bone disease. Callisto has two lead drugs in clinical development, Annamycin to treat relapsed leukemia, and Atiprimod to treat relapsed multiple myeloma. Callisto intends to initiate a Phase IIb clinical trial of Annamycin in relapsed acute lymphoblastic leukemia patients in mid 2005. Annamycin, a drug from the anthracycline family, has a novel therapeutic profile, including activity against resistant diseases and significantly reduced cardiotoxicity. Callisto’s second drug, Atiprimod, is in a Phase I/IIa clinical trial in relapsed multiple myeloma patients, and is a small-molecule, orally available drug with antiproliferative and antiangiogenic activity. Callisto also has drugs in preclinical development for melanoma, gastrointestinal inflammation, and a program focused on the development of a drug to protect against staphylococcus and streptococcus biowarfare agents. Callisto has exclusive worldwide licenses from AnorMED Inc. and M.D. Anderson Cancer Center to develop, manufacture, use and sell Atiprimod and Annamycin, respectively. For additional information, visit www.callistopharma.com.


Forward-Looking Statements

Certain statements made in this press release are forward-looking. 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 be correct. As discussed in the Callisto Pharmaceuticals Annual Report on Form 10-KSB for the year ended December 31, 2003,and other periodic reports, as filed with the Securities and Exchange Commission, actual results could differ materially from those projected in the forward-looking statements as a result of the following factors, among others: uncertainties associated with product development, the risk that products that appeared promising in early clinical trials do not demonstrate efficacy in larger-scale clinical trials, the risk that Callisto will not obtain approval to market its products, the risks associated with dependence upon key personnel and the need for additional financing.



For More Information:

Investor Relations:
Marty Tullio or Mark Tullio
McCloud Communications, LLC
949.553.9748
marty@McCloudCommunications.com
mark@McCloudCommunications.com

Company Contact:
Dan D’Agostino
Callisto Pharmaceuticals, Inc.
212.297.0010 x227
dagostino@callistopharma.com


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