SOURCE: Callisto Pharmaceuticals, Inc.

May 19, 2005 13:31 ET

Callisto Pharmaceuticals Announces Details of Upcoming Clinical Trial of Annamycin in Adult Relapsed/Refractory Acute Lymphoblastic Leukemia Patients

NEW YORK, NY -- (MARKET WIRE) -- May 19, 2005 -- Callisto Pharmaceuticals, Inc. (AMEX: KAL), a biopharmaceutical company primarily focused on the development of drugs to treat cancer, today announced further details of its planned trial of Annamycin in adults with relapsed/refractory acute lymphoblastic leukemia (ALL) patients planned to begin in mid-2005. The earlier Phase I trial of Annamycin performed in acute leukemia patients by a prior sponsor was recently subjected to a careful audit by Callisto of efficacy and safety data. Based on this review, the Company plans to include in the next trial with Annamycin in adult relapsed/refractory ALL patients an initial evaluation of a small number of patients (2 cohorts totaling approximately 6 patients) to reconfirm the initial safety data in a Phase I/IIa trial that will then be rolled into a larger Phase IIb trial.

"The trial we inherited from the prior sponsor has been carefully assessed and strongly supports moving rapidly into Phase II clinical trials in both ALL and AML patients," said Dr. Pamela Harris, Chief Medical Officer of Callisto Pharmaceuticals, Inc. "Because we did not sponsor, and, therefore, did not monitor patients, we believe the right course to take is to begin this next trial with a limited dose escalation trial of Annamycin in a small number of patients at doses below the previously determined maximum tolerated dose, and then immediately roll this study into a larger Phase II trial at a final fixed dose."

"The efficacy data from the earlier trial are particularly encouraging in that the two observed complete remissions were in patients whose disease had become resistant to other chemotherapeutic agents," said Dr. Donald Picker, Executive VP, Research and Development. "The plan for the next trial has involved a considerable amount of input from our consultants and from our Principal Investigators, Drs. Hagop Kantarjian and Michael Andreeff of the M.D. Anderson Cancer Center, and we are presently on schedule to get this trial underway in mid-2005."

About Callisto Pharmaceuticals, Inc.

Callisto is a biopharmaceutical company primarily focused on the development of drugs to treat cancer. 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 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

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