Novel Investigational Regimen Combining Radiation Enhancing Agent With Ibritumomab Tiuxetan (Zevalin(R)) Produces High Rate of C

LUGANO, Switzerland, June 5 /PRNewswire-FirstCall/ -- At the 10th International Conference on Malignant Lymphoma in Lugano, Switzerland data were presented from a phase I/II investigator-sponsored clinical trial of Yttrium-90 Ibritumomab Tiuxetan (90Y-Zevalin) combined with the novel expanded porphyrin motexafin gadolinium (MGd). The greatest benefit of this investigational regimen was observed in rituximab-refractory follicular lymphoma patients, who experienced rapid responses and a high rate of durable complete responses (CR). In this subset of patients (n=14), 64 percent experienced a complete response with a median estimated time to progression (TTP) of 14 months. These results compare favorably to prior published data of single agent Zevalin in terms of CR and TTP. The investigators concluded that MGd given with Zevalin does not appear to increase hematologic or other toxicities. Cell Therapeutics, Inc. (CTI) (Nasdaq and MTA: CTIC) markets Zevalin in the United States. MGd is under development by Pharmacyclics, Inc.

"Zevalin is approved for relapsed follicular non-Hodgkin's lymphoma based on superior overall and complete response rates compared to rituximab, including rituximab-refractory follicular non-Hodgkin's lymphoma where Zevalin resulted in a 74 percent overall response rate with 15 percent complete and unconfirmed complete responses," said James A. Bianco, M.D., President and CEO of CTI. "The results of the study suggest that addition of MGd may enhance the effectiveness of radioimmunotherapy with Zevalin. Further studies using this combination in patients with follicular or diffuse large B-cell lymphoma are warranted."

About the Study

Of the 30 patients enrolled on this study, 28 are currently evaluable. All patients were rituximab-refractory. No dose limiting toxicity was seen. No grade 4 non-hematologic toxicities were seen. Hematologic toxicities included 29 percent grade 3/4 neutropenia, with 7 percent being grade 4, 46 percent grade 3 thrombocytopenia, and 18 percent grade 3 anemia.

For all patients (n=28), overall response and complete response rates were 57 percent and 46 percent, respectively. Median time to progression for these patients was 11 months and the two-year overall survival was estimated to be 76 percent. For rituximab-refractory follicular lymphoma patients (n=14), overall response and complete response rates were 86 percent and 64 percent, respectively. Median time to progression for this subset of patients was 14 months and the two-year overall survival was estimated to be 93 percent. Notably, responses to the MGd/Zevalin combination were seen within the first four weeks of treatment.

About Zevalin(R)

Zevalin(R) (Ibritumomab Tiuxetan) is a form of cancer therapy called radioimmunotherapy and is indicated as part of the Zevalin therapeutic regimen for treatment of relapsed or refractory, low-grade or follicular B-cell non-Hodgkin's lymphoma, including patients with rituximab refractory follicular NHL. It was approved by the FDA in February of 2002 as the first radioimmunotherapeutic agent for the treatment of NHL.

Rare deaths associated with an infusion reaction symptom complex have occurred within 24 hours of rituximab infusions. Yttrium-90 Zevalin administration results in severe and prolonged cytopenias in most patients. Severe cutaneous and mucocutaneous reactions have been reported. The most serious adverse reactions of the Zevalin therapeutic regimen were primarily hematologic, including neutropenia, thrombocytopenia, and anemia. Infusion-related toxicities were associated with pre-administration of rituximab. The risk of hematologic toxicity correlated with the degree of bone marrow involvement prior to Zevalin therapy. Myelodysplasia or acute myelogenous leukemia was observed in 2 percent of patients (8 to 34 months after treatment). Zevalin should only be used by health care professionals qualified by training and experience in the safe use of radionuclides.

Patients and healthcare professionals can visit http://www.zevalin.com for more information.

About Cell Therapeutics, Inc.

Headquartered in Seattle, CTI is a biopharmaceutical company committed to developing an integrated portfolio of oncology products. For additional information, please visit http://www.CellTherapeutics.com.

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This press release 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 Zevalin include risks associated with preclinical and clinical developments in the biopharmaceutical industry in general and with Zevalin in particular including, without limitation, the potential failure of Zevalin to prove safe and effective in combination with MGd for treatment of lymphoma, determinations by regulatory, patent and administrative governmental authorities, competitive factors, technological developments, costs of developing, producing and selling Zevalin, 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. Except as may be required by law, CTI does not intend to update or alter its forward-looking statements whether as a result of new information, future events, or otherwise.

SOURCE Cell Therapeutics, Inc.