The News

Phase II Studies of TRISENOX in Multiple Myeloma and Myelodysplastic Syndrome Yield Promising Results

19/05/2004

Data from two studies recently published in international scientific journals

May 19, 2004 Seattle—A study by A. Raza, M.D. of Rush Medical Center, published in Leukemia Research, concluded that the combination of TRISENOX® (arsenic trioxide) injection and thalidomide in patients with myelodysplastic syndrome (MDS) produced multilineage hematologic responses in 25 percent of patients studied. A separate study by M. Hussein, M.D. of the Cleveland Clinic Foundation, published in the British Journal of Haematology, showed that TRISENOX as a mono-therapy resulted in a clinical benefit to patients with relapsed or refractory multiple myeloma with objective responses in 33 percent of patients studied.
Cell Therapeutics, Inc. (CTI) (NASDAQ/Nuovo Mercato: CTIC) markets TRISENOX in the U.S. and Europe.

In the MDS study, 28 patients with a confirmed diagnosis of MDS were treated with the combination of TRISENOX and thalidomide. Seven patients responded including one complete hematologic and cytogenetic response. Two trilineage responses were seen in patients with inv(3), a chromosomal abnormality associated with overexpression of a gene called EVI1 that is associated with poor outcome in both MDS and acute myelogenous leukemia. Three of the five patients who had high pre-therapy EVI1 levels showed unexpectedly good responses. Responses were noted in both low- and high-risk MDS, but were particularly striking for the high-risk patients. The combination was generally well tolerated, fluid retention and myelosuppression being the major toxicities observed. All side effects were reversible once the drugs were discontinued.

“Results of this combination study appear to be different than the experience with thalidomide alone as the responses from the combination regimen are more commonly multi-lineage and more high-risk patients appear to be responding,” stated Raza. “This study has been followed by an ongoing single-agent study of TRISENOX and thalidomide to determine if TRISENOX is as effective as a single-agent.”

In the Hussein multiple myeloma study, 24 multiple myeloma patients, 16 of whom were refractory to previous regimens, were treated with single-agent TRISENOX. Responses, defined as reductions of 25 percent or more in serum M-protein levels, occurred in eight of 24 patients (33 percent). An additional six patients (25 percent) achieved stable disease. The median time to response was 67 days, with a median duration of response lasting 130 days. Therapy was generally well tolerated, with mostly mild to moderate adverse events. Neutropenia was the most commonly reported side effect, however it was not associated with neutropenic fever. Notably, renal function improved during treatment in the two patients with myeloma kidneys.

“The clinical efficacy and favorable toxicity profile of TRISENOX demonstrated in this study argue for the further evaluation of the drug in relapsed or refractory multiple myeloma using new dosing strategies and combining TRISENOX with ascorbic acid as well as with traditional therapeutic agents, such as melphalan and dexamethasone, or with non-traditional agents, such as bortezomid and thalidomide,” stated Hussein.

About Cell Therapeutics, Inc.
Based in Seattle, CTI is a biopharmaceutical company committed to developing an integrated portfolio of oncology products aimed at making cancer more treatable. For additional information or a copy of the full prescribing information for TRISENOX, please visit http://www.cticseattle.com/.

About TRISENOX®
TRISENOX® (arsenic trioxide) is marketed by CTI. TRISENOX was approved for marketing in 2000 by the U.S. Food and Drug Administration to treat patients with relapsed or refractory acute promyelocytic leukaemia (APL), a rare, life-threatening form of cancer of the blood. TRISENOX was granted marketing authorization from the European Commission in March 2002. APL, one of eight subtypes of acute myeloid leukemia (AML), represents 10-15 percent of the more than 20,000 patients diagnosed with AML each year. TRISENOX is currently being studied in more than 40 clinical and investigator-sponsored trials in a variety of cancers.

U.S. marketing approval for TRISENOX was granted based on results from a U.S. multicenter study in which 40 relapsed APL patients were treated with TRISENOX 0.15 mg/kg until bone marrow remission or a maximum of 60 days. Thirty-four patients (85 percent) achieved complete remission. When the results for these 40 patients were combined with those for the 12 patients in a pilot trial, an overall response rate of 87 percent was observed.

WARNING: TRISENOX should be administered under the supervision of a physician who is experienced in the management of patients with acute leukemia. Some patients with APL treated with TRISENOX have experienced APL differentiation syndrome – with symptoms similar to retinoic acid acute promyelocytic leukemia (RA-APL) syndrome. Arsenic trioxide can cause QT prolongation (which can lead to torsade de pointes) and complete atrioventricular block.

The most common adverse events associated with TRISENOX have been generally manageable, reversible and usually did not require interruption of therapy. These have included hypokalemia, hypermagnesemia, hyperglycemia and thrombocytopenia as reported in 13 percent of the patients (n=40). Abdominal pain, dyspnea, hypoxia, bone pain and neutropenia were reported in 10 percent of these patients, while arthralgia, febrile neutropenia and disseminated intravascular coagulation were reported in eight percent of patients.

This announcement includes forward-looking statements that involve a number of risks and uncertainties, the outcome of which could materially and/or adversely affect actual future results. Specifically, the risks and uncertainties that could affect the development of TRISENOX include risks associated with preclinical and clinical developments in the biopharmaceutical industry in general and with TRISENOX in particular including, without limitation, the potential failure of TRISENOX to prove safe and effective for treatment of cancers other than APL, determinations by regulatory, patent and administrative governmental authorities, competitive factors, technological developments, costs of developing, producing and selling TRISENOX, and the risk factors listed or described from time to time in the Company’s filings with the Securities and Exchange Commission including, without limitation, the Company’s most recent filings on Forms 10-K, 8-K, and 10-Q.

For further information please contact:
Investors
Cell Therapeutics, Inc.
Leah Grant
T: 206.282.7100 F: 206.272.4010
E: invest@ctiseattle.com
www.cticseattle.com/investors.htm
Media
Cell Therapeutics, Inc.
Candice Douglass
T: 206.272.4472 F: 206.272.4010
E: media@ctiseattle.com
www.cticseattle.com/media.htm
Cell Therapeutics, Inc. (Europe)
Karl Hanks
T: 39 026 103 5807 F: 39 026 103 5601
E: karl.hanks@ctimilano.com