NEW YORK, NY–(MARKET WIRE)–Nov 12, 2003 — Callisto Pharmaceuticals, Inc., (OTC BB: CLSP) today announced that a poster entitled Atiprimod is a Novel Anti-Angiogenic and Anti-Cancer Drug Candidate will be presented at the Conference on Molecular Targets and Cancer Therapeutics in Boston, November 17-20, 2003. The conference, sponsored by the American Association for Cancer Research, the National Cancer Institute and the European Organization for Research and Treatment of Cancer, is being held at the Hynes Convention Center. Callisto’s poster, abstract number B29, will be presented at 12:30-1:30 p.m. and 5:30-6:30 p.m. in Hall C-D, Session B by Dr. Kunwar Shailubhai, Executive Vice President, Research & Development.
Atiprimod is Callisto’s lead drug candidate for multiple myeloma. Callisto recently filed an IND on Atiprimod for clinical evaluation in multiple myeloma patients, and a Phase I/IIa clinical trial is expected to begin shortly. According to Dr. Shailubhai, Atiprimod has unique properties, centering on its ability to inhibit angiogenesis and proliferation of cancer cells, as well as its ability to inhibit production of vascular endothelial growth factor (VEGF) and Interleukin-6 (IL-6), two essential factors for tumor growth and metastasis in multiple myeloma and other solid tumors.

About Callisto Pharmaceuticals, Inc.

Callisto is a biopharmaceutical company primarily focused on the development of drugs to treat multiple myeloma, other cancers and osteolytic bone disease. Callisto’s lead drug candidate, Atiprimod, is a small-molecule, orally available drug with antiproliferative and antiangiogenic activity. Callisto’s second anticancer program is focused on the development of an analog of the human intestinal hormone, uroguanylin, to treat colon cancer. Callisto has two operating subsidiaries, Callisto Research Labs, LLC and Synergy Pharmaceuticals Inc.

Included in this release are “forward-looking: statements. 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 have been correct. Callisto’s actual results could differ materially from those anticipated in the forward-looking statements as a result of various factors.