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New Treatment Regimen May Improve Mantle Cell Lymphoma: Presented at ASH

By Mike Fillon

ATLANTA, GA -- December 14, 2005 -- A new study shows that chemotherapy paired with Y-ibritumomab tiuxetan (Zevalin) might improve outcomes for patients with mantle cell lymphoma (MCL).

This new regimen included treatment with Y-ibritumomab tiuxetan, a monoclonal antibody with an attached radioactive substance (yttrium), along with standard chemotherapy for MCL including fludarabine, cyclophosphamide, and mitoxantrone (FCM).

Results of the study were presented here December 11^th at the 47^th Annual Meeting of the American Society of Hematology (ASH).

Specifically, results of the study show that 75% of patients on this regimen shifted from a partial response (PR) to complete response (CR) with no palpable lymph nodes or measurable masses on computed tomograph. Also, the addition of Y-ibritumomab tiuxetan to FCM increased overall response rate (ORR) from 46% to 58%.

MCL is a non-Hodgkin's B-cell lymphoma sometimes called diffuse small-cleaved cell lymphoma, intermediate differentiation lymphoma or centrocytic lymphoma. MCL primarily strikes men over 50, who almost always present with advanced stage III or IV disease. Bone marrow involvement is seen in 60% to 90% of patients.

Lead researcher Wojciech Jurczak, MD, PhD, professor, department of hematology, Collegium Medicum Jagiellonian University, Cracow, Poland, said that historically, MCL has been resistant to current standard chemotherapeutic approaches.

Dr. Jurczak noted that conventional nonmyeloablative radioimmunotherapy (RIT) without prior fludarabine-based chemotherapy has been unsuccessful in MCL patients because tumor burdens were large and because of the sink phenomenon, which can limit the efficacy of radiofrequency ablation.

"These results indicate that fludarabine use prior to RIT may actually sensitize the tumor to the radiotoxic effects of RIT, thereby debulking tumor burden, which may enhance the therapeutic benefit," Dr. Jurczak said.

In his study, Dr. Jurczak and colleagues enrolled 26 patients, and 23 of them received this new regimen. To date, 20 patients have completed the entire protocol. Following treatment with Y-Ibritumomab tiuxetan, 80% achieved CR, with 3 others achieving a greater nonprogressive partial response after being treated with Y- Ibritumomab tiuxetan.

One patient achieved PR, progressing in 6 months. Dr. Jurczak said therapeutic response is being monitored at 6 weeks and 3 months followed by 3-month intervals for up to 2 years to assess time to progression.

In most patients, white blood cell and platelet counts decreased in the first 4 to 5 weeks after being treated with Y-Ibritumomab tiuxetan, with cytopenias lasting an average of 8 to 10 weeks.

Despite prolonged neutropenia and thrombocytopenia, adverse effects were manageable, Dr. Jurczak said. None of the patients developed serious, life-threatening infections, although 6 patients required hospitalization, including 4 for prolonged and recurrent conditions such as pneumonia.

Patients were treated with 3 to 6 3-week cycles of the current chemotherapy standard -- fludarabine, cyclophosphamide, and mitoxantrone and rituximab (FCM +/- R) -- to reduce the tumor burden.

Upon completion of the third cycle, tumor regression was assessed and patients achieving CR or PR were enrolled in the Y-Ibritumomab tiuxetan consolidation step; patients received 250 mg/m² of rituximab, followed by a second dose of rituximab and Y-Ibritumomab tiuxetan.


[Presentation title: Consolidation of Chemotherapy Response in Mantle Cell Lymphoma (MCL) Patients With 90Y-Ibritumomab Tiuxetan (90Y-Zevalin) Radioimmunotherapy (RIT). Abstract 2453]

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