Treatment of mantle-cell lymphoma with Rituximab (chimeric monoclonal anti-CD20 antibody): analysis of factors associated with response

BACKGROUND: A retrospective analysis was performed to delineate the factors associated with response, and to determine the duration of response, in 87 patients with CD20-positive mantle-cell lymphoma (MCL) treated with Rituximab (chimeric monoclonal anti-CD20 antibody) in two prior studies. PATIENTS AND METHODS: Patients with newly-diagnosed MCL (MCL1, n = 37), and previously-treated MCL (MCL2, n = 50), received single-agent Rituximab, in the context of two multicentre clinical studies using different schedules and doses, conducted in 1996 and 1997. A follow-up analysis was performed at the end of 1998, including all 81 patients who completed therapy. Statistical modeling of factors associated with response was performed using ordered logistic regression. The duration of complete (CR) and partial response (PR), and the time to disease progression (TTP), were also derived. RESULTS: The overall response rate (RR) was 34% (30 of 87) (81 evaluable patients, RR 37%; CR 14%), and was equivalent for MCL1 and MCL2. On univariate analysis, elevated LDH (P = 0.004); prior therapy with alkylating agents (P = 0.01) or fludarabine phosphate (P = 0.04); WHO performance status = 2 (P = 0.02); MCL2 refractory to last prior therapy (P = 0.04); and splenomegaly (P = 0.04), each at the time of treatment with Rituximab, were significantly associated with a lower RR. On multivariate analysis, only LDH (P = 0.007) and prior alkylating agents (P = 0.03) retained statistical significance. At a median follow-up of 1.4 years, the median TTP was 7 months. The median duration of response was one year, and was significantly longer for patients achieving CR vs. PR (P = 0.04). CONCLUSIONS: Rituximab is active in MCL, and can induce complete responses in a minority of patients. Elevated LDH at the time of therapy, and prior therapy with alkylating agents, are associated with a significantly lower RR. The duration of response of one year is similar to that previously reported in follicular lymphoma