Callisto Details Clinical Research Progress on Proprietary Anti-Cancer Drugs and Strategic Initiatives for 2006; Expected Start of Pediatric Trial of L-Annamycin to Treat Children with Leukemia Among Goals Noted in Investor Presentation.

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 the availability of an investor presentation outlining the Company's recent clinical and strategic initiatives in development of two new drugs to treat serious hematological cancers, as well as to develop a proprietary breakthrough first-in-class drug for gastro-intestinal disease for which the Company recently received a patent allowance.

Dr. Gary S. Jacob, Callisto CEO and Chief Scientific Officer, outlined the recent milestones and development goals for the Company's two lead anti-cancer drugs, L-Annamycin and Atiprimod. He also discussed the Company's strategic goals to accelerate pre-clinical development of a proprietary next-generation drug for colon cancer and gastro-intestinal disease called SP304 into the 2006 calendar year.

Dr. Jacob detailed the Company's achievements and goals in an investor presentation delivered December 3 at the Southern California Investment Association's "National Investment Conference" in Irvine, CA.

In an achievement unusual for a Company of its size and stage, Callisto has already advanced two of its anti-cancer drugs L-Annamycin and Atiprimod to clinical trials.

L-Annamycin is being developed to treat patients with relapsed forms of the two major types of acute relapsed leukemias. Among the drug's unique therapeutic benefits is an ability to attack cancers resistant to other available drugs. Callisto recently announced the milestone launch of a clinical trial on L-Annamycin in adult patients with acute lymphocytic leukemia. The trial is being conducted at The University of Texas M.D. Anderson Cancer Center, one of the world's preeminent institutions for cancer research and treatment.

Atiprimod, which the Company is developing as a treatment for the blood cancer multiple myeloma, has demonstrated very significant therapeutic activity in recent pre-clinical animal model research. Three scientific abstracts covering both clinical and preclinical results on Atiprimod will be presented at the upcoming Dec. 10-13 American Society of Hematology (ASH) conference in Atlanta, GA. In particular, two of these abstracts, covering the clinical and animal model data, were chosen for high-profile oral presentations at the conference. These will be presented by researchers from both M.D. Anderson Cancer Center and the Dana-Farber Cancer Institute, two leading cancer research institutions.

Specific points made by Dr. Jacob in his presentation include the following:

L-Annamycin - Clinical Trials:

--Initiate in 4Q 2005 an open-label single-agent clinical trial of Annamycin in adult relapsed ALL patients.

--Commence a single agent trial of liposomal Annamycin in pediatric relapsed ALL patients.

--Commence a combination trial of liposomal Annamycin in combination with Ara-C in adult relapsed AML patients.

--Callisto plans to provide interim results on the first wave of Annamycin clinical trials as these data come available in 2006.

Atiprimod -- Invited Talks and Presentations:

--Up-to-date clinical results on Atiprimod trial. Dr. Michael Wang (PI - M.D. Anderson Cancer Center) presents at 5pm Sunday, Dec. 11 in session entitled: "Multiple Myeloma: Novel Therapeutic Approaches"

--Animal and pre-clinical data on Atiprimod. Dr. Paola Neri (Dana-Farber Cancer Institute) presents at 8am Monday, Dec. 12 in session entitled: "Multiple Myeloma: Novel Therapy."

--Atiprimod abstract by M.D. Anderson group describing activity against leukemia cells and potential to treat myelodisplastic syndrome. (Poster presentation.)

SP304 - Proprietary Drug for Gastro-Intestinal Disease and Colon Cancer:

--Plan to accelerate preclinical development of this innovative therapy with the intention of filing an investigational drug (IND) application in late 2006.

The complete presentation given by Dr. Jacob at the SCIA meeting can be viewed online at http://www.trilogy-capital.com/tcp/callisto/powerpoint.html.

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 relapsed acute lymphoblastic 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 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 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.