Callisto Pharmaceuticals Receives Going Concern Qualification in 2005 Audit Report; Company Updates Cash Position Status and Recent Financing Activities.

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, announced today updated information with respect to the Company's cash position following its latest financing activities. In addition, in compliance with American Stock Exchange Rule 610(b), it also announced that the Company's independent registered public accountants included an explanatory paragraph in their opinion on the Company's financial statements included in the recently filed Form 10-K for the year ended December 31, 2005, relating to the Company's ability to continue as a going concern.

The Company ended 2005 with approximately $1.4 million in cash and cash equivalents. In addition, as previously announced, in February 2006, the Company increased its cash position through the successful completion of a financing totaling approximately $5.14 million in gross proceeds through a private placement involving common stock and warrants.

The Company also announced that it has closed on an additional $390,000 on the same terms as the February 2006 private placement bringing the year to date total gross proceeds to approximately $5.5 million. The Company continues to actively explore financing alternatives, including equity financings.

The Company's annual report on Form 10-K is available from the SEC's website at http://www.sec.gov or the "Investor Information" section of the Company's website at www.callistopharma.com.

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 other significant health care markets, including ulcerative colitis and biodefense. One of the Company's lead drug candidates, L-Annamycin, is being developed as a treatment for forms of relapsed acute 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, and advanced carcinoid cancer. Atiprimod is presently in Phase I/IIa human clinical trials in relapsed multiple myeloma patients, and advanced cancer patients, respectively. 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 for the year ended December 31, 2005, 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.