First-line and maintenance treatment with rituximab for patients with indolent non-Hodgkin's lymphoma.

The chimeric human-mouse anti-CD20 monoclonal antibody rituximab has durable single-agent activity in patients with relapsed and refractory indolent non-Hodgkin's lymphoma. The focus of this report is a phase II trial evaluating the efficacy of single-agent rituximab as first-line therapy in patients with indolent lymphoma and scheduled maintenance treatment in prolonging duration of remission. Patients received a 4-week course of standard rituximab (375 mg/m(2) intravenously weekly x 4). Those achieving objective response or stable disease then received maintenance courses of standard rituximab every 6 months, for a maximum of four rituximab courses. Of 62 patients entered in the trial, 61% had follicular lymphoma while 39% had small lymphocytic lymphoma (SLL). At 6 weeks, 28 of 60 evaluable patients (47%) had an objective response. The response rate improved to 73% (37% complete response) following maintenance rituximab therapy and was similar in patients with follicular lymphoma and SLL (76% v 70%, respectively). Median progression-free survival for the entire group was 34 months. Single-agent therapy was well tolerated and maintenance rituximab was administered without grade 3/4 toxicity. Because of the higher activity of rituximab in this study compared with previous results in patients with relapsed or refractory SLL, a second phase II trial of identical design but limited to patients with SLL and chronic lymphocytic leukemia was initiated. Forty-four patients entered this second trial and, at present, 27 continue to receive maintenance courses of rituximab. The current response rate is 56% (8% complete responses). In summary, rituximab appears highly active as first-line single-agent therapy for indolent non-Hodgkin's lymphoma and responses may be improved with maintenance courses of rituximab. Results suggest a higher response rate to rituximab when used as first-line compared with second/third-line treatment, particularly in the subset of patients with SLL and chronic lymphocytic leukemia. Further follow-up will provide important information regarding the impact of first-line and maintenance rituximab on progression-free survival in patients with indolent non-Hodgkin's lymphoma.