Rituximab monoclonal antibody as initial systemic therapy for patients with low-grade non-Hodgkin lymphoma

Rituximab, a chimeric antibody that targets CD20(+) B cells, produces a 48% response rate in patients with refractory low-grade non-Hodgkin lymphoma. In this phase II trial, patients with low-grade non-Hodgkin lymphoma who ha d previously received no systemic therapy were treated with rituximab, 375 mg/m(2), administered by IV infusion for 4 consecutive weeks. Patients with objective response or stable disease received repeat 4-week courses of rit uximab at 6-month intervals. At the time of initial reevaluation at 6 weeks , 21 of 39 patients (54%) had objective response to treatment, and an addit ional 14 patients (36%) had stable disease or minor response. Response rate s were similar in patients with follicular and small lymphocytic (CLL-type) lymphoma (52% versus 57%, respectively). At present, follow-up is short an d only 13 patients have undergone a second course of rituximab treatment. H owever, 4 additional responses were documented either prior to the second c ourse of rituximab (2 patients) or following the second course (2 patients) and 4 patients improved from partial to complete response. The current res ponse rate is 64%, with 6 complete responses (15%), Treatment with rituxima b was well tolerated, with only 1 patient experiencing grade 3/4 infusion-r elated toxicity. Rituximab is well tolerated and highly active in patients with low-grade non-Hodgkin lymphoma previously untreated with systemic ther apy. Although further follow-up is required, the demonstration of minimal t oxicity and considerable activity of this new biologic agent represents an important beginning of more specific, less toxic treatment for this importa nt group of cancer patients. (C) 2000 by The American Society of Hematology .