Callisto Pharmaceuticals Completes Enrollment of Phase II Trial of Atiprimod in Neuroendocrine Cancer

New York (ots/PRNewswire) -

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

Web site: http://www.callistopharma.com
http://www.clinicaltrials.gov

ots Originaltext: Callisto Pharmaceuticals. Inc.
Im Internet recherchierbar: http://www.presseportal.de

Contact:
Gary Jacob of Callisto Pharmaceuticals, Inc., +1-212-297-0010,
jacob@callistopharma.com