NEW YORK, Sept. 20 /PRNewswire-FirstCall/ -- Callisto Pharmaceuticals, Inc. (Amex: KAL; FWB: CA4), a developer of new drug treatments in the fight against cancer and gastrointestinal disorders and diseases, announced today that complete enrollment of its Phase II clinical trial of Atiprimod to treat low to intermediate grade neuroendocrine carcinoma (advanced carcinoid cancer) was accomplished ahead of schedule. The trial, designed to enroll 40 patients, presently has patients enrolled at seven clinical sites in the U.S., and was closed to further enrollment with the addition of the 40th patient. "This Atiprimod trial was initiated in November, 2006 and we are pleased with the tremendous pace of enrollment that we experienced," said Dr. Gary S. Jacob, Chief Executive Officer of Callisto. "We have patients who have now been on our drug for as long as 11 months, and we expect that by January of 2008 the bulk of patients will have been treated for 6 months or more on our drug. We anticipate at that time releasing interim data from the trial as well as planning for a meeting with FDA on the design of a registration trial." The primary objective of the Phase II clinical trial was to evaluate efficacy of Atiprimod in patients with low to intermediate grade neuroendocrine carcinoma who have metastatic or unresectable cancer and who have progression of their disease despite standard therapy (octreotide). Patients, after signing an informed consent, were required to complete two weeks of a symptoms diary to establish their symptoms baseline before commencing Atiprimod dosing. Efficacy evaluations include the measure of target lesions (per RECIST), and the quantization of symptom relief. Further details of this trial can be found at http://www.clinicaltrials.gov/. About Atiprimod Atiprimod is an orally bio-available small molecule drug that displays multiple mechanisms of action. The drug has been shown to be antiangiogenic, inhibit secretion of VEGF and IL-6, elicit an apoptotic response (programmed cellular death), and inhibit phosphorylation of key kinases involved in tumor progression and survival including Akt and STAT3. The drug is presently in two clinical trials: a Phase II trial in advanced carcinoid cancer patients, and a Phase I/IIa human clinical trial in relapsed or refractory multiple myeloma patients. Callisto earlier announced in June, 2006 interim data from a Phase I trial of Atiprimod in advanced cancer patients. The patients who were entered into this trial had growing tumors and symptoms that were no longer controlled by the standard therapies utilized. During treatment, three of the five advanced carcinoid patients had measurable tumor regressions and loss of many of the debilitating symptoms of this disease. About Carcinoid Cancer Carcinoid tumors, or carcinoids, originate in hormone-producing cells of the gastrointestinal (GI) tract, the respiratory tract, the hepatobiliary (liver) system and the reproductive glands. The most common site of origin is the GI tract, with tumors often developing in the rectum, and other sections of the small intestine. Approximately 7,000 cases of carcinoid cancer are diagnosed in the U.S. annually, with the number increasing over the past 20-30 years. Carcinoid tumors that metastasize to the liver have a poor prognosis. Traditionally, chemotherapy relieves symptoms in less than 30% of cases of metastatic carcinoid tumors, usually for less than 1 year. Carcinoid tumors typically produce a condition called "carcinoid syndrome" which is caused by the release of hormones by the tumors into the blood stream. The symptoms vary depending on which hormones are released by the tumors, but typically include diarrhea, facial flushing, wheezing, abdominal pain and valvular heart disease. About Callisto Pharmaceuticals, Inc. Callisto is a biopharmaceutical company focused on the development of new drugs to treat various forms of cancer and gastrointestinal diseases. Callisto's drug candidates in development currently include anti-cancer agents in clinical development, in addition to drugs in pre-clinical development for other significant health care markets, including gastrointestinal disorders. One of the Company's lead drug candidates, Atiprimod is presently in a Phase II clinical trial in advanced carcinoid cancer patients, a neuroendocrine tumor, and in a Phase I/IIa human clinical trial in relapsed or refractory multiple myeloma patients. Another anti-cancer drug, L-Annamycin, is being developed as a treatment for forms of relapsed or refractory acute leukemia, a currently incurable blood cancer. L-Annamycin is currently in a Phase I clinical trial in adult relapsed or refractory acute lymphocytic leukemia, and in a Phase I clinical trial in children and young adults with refractory or relapsed acute lymphocytic leukemia or acute myelogenous leukemia. L- Annamycin, a member of the anthracycline family of proven anti-cancer drugs, has a novel therapeutic profile, including potential activity against multi- drug resistant tumors and significantly reduced cardiotoxicity, or damage to the heart, compared to currently available drug alternatives. Callisto also has a proprietary drug Guanilib in preclinical development for gastro- intestinal disorders. Callisto has exclusive worldwide licenses from Genzyme Inc. and M.D. Anderson Cancer Center to develop, manufacture, use and sell Atiprimod and L-Annamycin, respectively. Callisto is also listed on the Frankfurt Stock Exchange under the ticker symbol CA4. More information is available at http://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, 2006, 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. CONTACT: Gary Jacob of Callisto Pharmaceuticals, Inc., +1-212-297-0010 DATASOURCE: Callisto Pharmaceuticals, Inc. CONTACT: Gary Jacob of Callisto Pharmaceuticals, Inc., +1-212-297-0010, Web site: http://www.callistopharma.com/ http://www.clinicaltrials.gov/

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