Clinical research has shown that the recurrence of Mantle Cell Lymphoma, a variant of malignant lymphoma, can be reduced by almost 50% in patients who receive maintenance treatment with the antibody rituximab (Rituxan?, Genentech / Biogen Idec). These results were presented by Hanneke Kluin-Nelemans, M.D. from the University Medical Center of Groningen, The Netherlands at the 16th Congress of the European Hematology Association in London.

Mantle cell lymphoma, an aggressive and fast-growing type of B-cell non-Hodgkin lymphoma representing a variant of malignant lymphoma, characteristically affects people above 60 years. Multiple lymph nodes, bone marrow, spleen, and blood are often involved. Treatment consists of 6-8 chemotherapy cycles combined with the antibody rituximab. Despite this, only half of the patients show a complete response, and almost all responding patients have a recurrence of the disease within a few years. Therefore, the outcome is poor, with half of the patients above the age of 60 dying from the disease within 3-5 years.

Maintenance therapy with rituximab
Commenting on the trial results Kluin-Nelemans noted ?We wanted to find out whether recurrence of the disease could be postponed and thereby survival could be prolonged. To this end, we introduced maintenance therapy with rituximab, one injection every 2 months, beginning after successful initial chemotherapy.?

Rituximab vs. interferon-alpha
Within the European Mantle Cell Lymphoma Network, a very large group of 560 elderly patients (median age 70 years) from 8 different countries, all with extensive mantle cell lymphoma were treated. Patients received two different initial chemotherapy regimens combined with rituximab. Then, 288 patients who showed a response were randomized and treated with either rituximab (one injection per 2 months), or interferon-alpha (one injection per week). Maintenance therapy was continued until progression or recurrence of the lymphoma.

Limiting the risk of lymphoma progression
Data from 248 patients treated with maintenance therapy are available. It appeared that maintenance therapy with rituximab could reduce the risk of lymphoma progression by 46% resulting in 57% of patients being in remission (without disease symptoms or signs) 4 years later, in comparison to 26% treated with interferon. It is too early to reliably determine whether this will translate into an improvement in survival. So far, at 4 years after start of first therapy, 77% of the patients on rituximab were alive, versus 62% of the patients on interferon. Patients who had been successfully treated initially with the so-called R-CHOP regimen (a combination of Rituximab, Cyclophosphamide, Doxorubicin Hydrochloride (Hydroxydaunomycin), Vincristine Sulfate (Oncovin) and Prednisone) did extremely well with 87% surviving at 4 years.

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Rituximab was better tolerated than interferon. 34% of patients without disease signs or symptoms, stopped the maintenance therapy because of side effects or other reasons in the rituximab group versus 80% in the interferon group. Rituximab had some ? generally very mild ? suppression effect on white blood cell production. Serious infections were seen in only 7%.

Based on the outcome of the study, the researchers concluded that the addition of rituximab maintenance treatment to elderly patients with mantle cell lymphoma who respond upon initial standard chemotherapy almost doubles the chance of remission 4 years from start of treatment. Therapy is safe and well tolerated in the large majority of patients.

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