Callisto Announces Appointment of Dr. Arthur Sytkowski as Clinical Trial Advisor and Medical Safety Monitor; Veteran Scientist and Harvard Professor to Guide Callisto's Expanding Clinical Programs for Atiprimod and L-Annamycin.

NEW YORK -- Callisto Pharmaceuticals, Inc. (AMEX:KAL) (FWB:CA4), a developer of new drug treatments in the fight against cancer and other major health threats, has announced that Dr. Arthur Sytkowski, Associate Professor of Medicine at Harvard University, has agreed to serve as Callisto's Clinical Trial Advisor and Medical Safety Monitor. Dr. Sytkowski will advise on Callisto's expanding clinical programs to develop its anticancer drugs Atiprimod and L-Annamycin.

Dr. Sytkowski brings to Callisto considerable experience with clinical development of cancer drugs from Phase I through Phase III, which he has gained through experience with a number of leading pharmaceutical and biotechnology companies.

"We are pleased to have someone of Dr. Sytkowski's depth of experience to oversee further development of our clinical trials and to help us move forward with Callisto's considerable clinical program," said Callisto Pharmaceuticals Executive Vice President Dr. Donald H. Picker. "Callisto has a very ambitious clinical plan for 2006, centered on our two drugs in the clinic, Atiprimod and L-Annamycin. Dr. Sytkowski will provide advice on drafting protocols, and on implementing and overseeing additional clinical trials."

Dr. Sytkowski is Director of the Laboratory for Cell and Molecular Biology, Division of Hematology and Oncology at Beth Israel Deaconess Medical Center, Harvard Medical School. Dr. Sytkowski, who is board certified in internal medicine, received his M.D. degree from the Medical College of Wisconsin, followed by an internship and medical residency at the Peter Bent Brigham Hospital and a hematology/oncology fellowship at the Boston Children's Hospital and the Dana Farber Cancer Institute, all at Harvard Medical School.

Dr. Sytkowski has been an Associate Professor of Medicine at Harvard Medical School since 1986, and a Staff Physician at Beth Israel Deaconess Medical Center, Boston. Dr. Sytkowski has been in active practice in the areas of internal medicine and of pediatric and adult oncology and hematology, and in the past 10 years has been an advisor to numerous companies on the design and execution of clinical trials.

About Callisto Pharmaceuticals, Inc.

Callisto is a biopharmaceutical company focused on the development of new drugs to treat various forms of cancer and other serious afflictions. Callisto's drug candidates in development currently include anti-cancer agents in clinical development, in addition to drugs for a range of other significant health care market segments, including biodefense. One of the Company's lead drug candidates, L-Annamycin, is being developed as a treatment for forms of relapsed leukemia, a currently incurable blood cancer. Callisto initiated a clinical trial of L-Annamycin in adult relapsed acute lymphocytic leukemia patients in 4Q 2005. L-Annamycin, a new compound from the anthracycline family of proven anti-cancer drugs, has a novel therapeutic profile, including activity against resistant diseases and significantly reduced cardiotoxicity, or damage to the heart, compared to currently available drug alternatives. Another anti-cancer drug, Atiprimod, is in development to treat relapsed multiple myeloma, a blood cancer. Atiprimod has entered Phase I/IIa human clinical trials in relapsed multiple myeloma patients. Callisto also has drugs in preclinical development for gastro-intestinal 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 L-Annamycin, respectively. For investor-specific information about Callisto, including recent news and stock price data, please visit http://www.trilogy-capital.com/tcp/callisto/. For an Investor Fact Sheet about Callisto, please visit http://www.trilogy-capital.com/tcp/callisto/factsheet.html. To view an informational presentation of the Company's development pipeline of drug candidates, visit http://www.trilogy-capital.com/tcp/callisto/powerpoint.html. Callisto is also listed on the Frankfurt Stock Exchange under the ticker symbol CA4. 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-K/A 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.