SOURCE: Callisto Pharmaceuticals, Inc.

May 04, 2005 07:00 ET

Callisto Pharmaceuticals Announces Interim Status of Atiprimod Phase I/IIa Trial in Relapsed Multiple Myeloma Patients

NEW YORK, NY -- (MARKET WIRE) -- May 4, 2005 -- Callisto Pharmaceuticals, Inc. (AMEX: KAL), a biopharmaceutical company primarily focused on the development of drugs to treat cancer, today announced the interim status of its Phase I/IIa trial with Atiprimod in patients with multiple myeloma, entitled "An Open-Label Study of the Safety and Efficacy of Atiprimod Treatment for Patients with Refractory or Relapsed Multiple Myeloma."

The trial is currently underway at four clinical sites in the United States. Three patient cohorts have now completed dosing at 30, 60 and 90 mg, respectively, and a fourth dosing cohort is currently underway at 120 mg. No dose limiting toxicities have been observed, to date. A fifth dose cohort at 180 mg is anticipated to begin in the next 6-8 weeks. No additional clinical sites are anticipated for this trial, as a pronounced increase in patient accrual has occurred in the past few months.

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, 2004, 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.

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