Cell Therapeutics CHOP-Zevalin Investigational Regimen Produces 95% Complete Remission and 75% Estimated Two Year Progression-Free Survival in Elderly Patients with Diffuse Large B-cell Lymphoma

03-25-2008

Cell Therapeutics, Inc. (CTI) today announced the publication, by two European institutions, of results of a limited phase II study of CHOP chemotherapy (cyclophosphamide, doxorubicin, vincristine, and prednisone) followed by administration of Zevalin(R) (Ibritumomab Tiuxetan) in elderly patients (60 years of age or older) with previously untreated diffuse large B-cell lymphoma (DLBCL). In this study, 20 previously untreated elderly patients were treated with a novel combination of six cycles of CHOP chemotherapy followed by Zevalin given six to ten weeks later. The study, which had an overall response rate (ORR) of 100 percent, including a 95 percent complete remission (CR) rate, indicated the efficacy, tolerability, and feasibility of this regimen for these patients. Results of the study were reported in the online edition of February 2008 Annals of Oncology. CTI acquired the U.S. rights to Zevalin in December, 2007.

"Although a small phase II experience, these results in elderly lymphoma patients treated with Zevalin following CHOP without rituximab demonstrate high rates of complete remissions and overall survival and are consistent with the potential to use Zevalin as consolidation therapy in aggressive lymphoma," noted Jack W. Singer, M.D., Chief Medical Officer of CTI. "We continue to be impressed with the high rate of conversion of partial to complete remissions following Zevalin consolidation irrespective of whether or not rituximab therapy is utilized. This publication demonstrates this in elderly patients with DLBCL while similar data in indolent lymphomas were reported at ASH 2007 from the Phase III FIT study. We are currently testing this clinically important potential of Zevalin consolidation in our ongoing phase III post-marketing commitment trial."

Details of the Study

The phase II trial, reported by P.L. Zinzani et. al. from the Institute of Hematology and Medical Oncology at the University of Bologna and the Department of Nuclear Medicine at S. Orsola-Malpighi Hospital in Bologna Italy, was a prospective, single-arm, open-label, non-randomized study combining CHOP chemotherapy (cyclophosphamide, doxorubicin, vincristine, and prednisone) plus Zevalin, which was conducted to evaluate the efficacy and safety of this regimen as first-line therapy in elderly (60 years of age or older) DLBCL patients. The ORR was 100 percent, including 95 percent CR and 5 percent partial remission (PR). Four (80 percent) of the five patients who achieved less than a CR with CHOP improved their remission status after receiving Zevalin. With a median follow-up of 15 months, the 2-year progression-free survival was estimated to be 75 percent, with a 2-year overall survival of 95 percent. The toxicity associated with Zevalin included severe (grade 3 or 4) hematologic toxicity in 12 of 20 patients; the most common severe side effects were neutropenia (12 patients) and thrombocytopenia (7 patients). Transfusions of platelets were given to one patient.

About Zevalin(R)

Zevalin(R) (Ibritumomab Tiuxetan) is a form of cancer therapy called radioimmunotherapy and is indicated for the treatment of patients with relapsed or refractory low-grade or follicular B-cell NHL, including patients with Rituximab-refractory 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 aimed at making cancer more treatable. For additional information, please visit http://www.cticseattle.com.

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 further studies in combination with CHOP for first-line treatment of elderly patients with diffuse large B-cell lymphoma or to be developed further in this combination for this indication, 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.

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