The News

TRISENOX® Produces Hematologic Responses in 27 Percent of MDS Patients

14/06/2004

Responses seen in both high-risk and low-risk patients

June 14, 2004 Seattle and Bresso—At the 9th Congress of the European Hematology Association (EHA), on June 10, 2004, preliminary data were presented from a phase II study of TRISENOX® (arsenic trioxide) injection in myelodysplasia (MDS). The multicenter European study, led by Norbert Vey, M.D. of Institut Paoli-Calmettes in patients with both high-risk (HR) and low-risk (LR) MDS, showed that single-agent TRISENOX produced a defined hematologic response rate of 27 percent (nine of 39 LR, 18 of 62 HR). Encouragingly, nine of 48 patients (19 percent) who had single-lineage red blood cell transfusion dependence became transfusion independent after TRISENOX treatment. Median duration of response on the study was approximately four months (range 2-10 months). The full duration of these responses is not yet known as twenty patients were still responding at the time of data release. Cell Therapeutics, Inc. (CTI) (NASDAQ and Nuovo Mercato: CTIC) markets TRISENOX in the United States and Europe.

“These results establish the clinical activity of TRISENOX in MDS. Most notable were the high number of patients achieving transfusion independence. Given this positive activity in both low- and high-risk MDS patients and the good safety profile, TRISENOX is a prime candidate to investigate in combination therapy,” stated Vey.

The objectives of the study are to determine the safety and efficacy of single agent TRISENOX in patients with low-risk and high-risk disease. TRISENOX was administered at a dose of 0.3 mg/kg for five days in the first week and 0.25 mg/kg twice weekly thereafter. Responses were observed across all hematologic lineages in high-risk patients and included one complete response (CR). In low-risk patients, responses were seen in two lineages. In addition to the nine patients who became red blood cell transfusion independent, five others had their red blood cell transfusion requirements reduced by more than 50 percent. There were also a total of three of 38 patients (seven percent) who became platelet transfusion independent, with two others experiencing a reduction in transfusion dependence by 50 percent. Most treatment-related adverse events were mild to moderate with one reported case each of grade 4 thrombocytopenia, neutropenia and edema NOS.

 “This is the second largest study of TRISENOX in MDS to demonstrate a clinically beneficial response in platelet and neutrophil as well as red blood cell lineages in both high- and low-risk patients,” noted Jack W. Singer, M.D. and Chief Medical Officer at CTI. “With more than 180 patients treated in phase II studies, we are now planning investigational trials of TRISENOX in combination with the recently approved demethylating agent, 5 azacytidine. We believe treatment of MDS still has a significant unmet need and that TRISENOX may supplement the utility of 5 azacytidine and other experimental agents to improve the response rates and outcome for patients with MDS.”

About TRISENOX®
TRISENOX® (arsenic trioxide) is marketed by Cell Therapeutics, Inc. (CTI) (NASDAQ: CTIC). TRISENOX® was approved for marketing in 2000 by the U.S. Food and Drug Administration to treat patients with relapsed or refractory Acute Promyelocytic Leukemia (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 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 CR. 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 acute promyelocytic leukemia (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.

About Cell Therapeutics, Inc.
Headquartered 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 and a copy of the prescribing information for TRISENOX®, please visit www.cticseattle.com.

This announcement includes forward-looking statements about preliminary data from clinical trials 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 continued 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 MDS, the potential failure of clinical trials of TRISENOX® in MDS, 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.

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