Rituximab anti-CD20 monoclonal antibody therapy in non-Hodgkin's lymphoma:: Safety and efficacy of re-treatment

Purpose: This phase II trial investigated the safety and efficacy of re-treatment with rituximab, a chimeric anti-CD20 monoclonal antibody, in patients with low-grade or follicular non-Hodgkin's lymphoma who relapsed after a response to rituximab therapy. Patients and Methods: Fifty-eight patients were enrolled onto this study, and two were re-treated within the study. patients received an intravenous infusion of 375 mg/m(2) of rituximab weekly for 4 weeks. All patients had at least two prior therapies and had received at least one prior course of rituximab, with a median interval of 14.5 months between rituximab courses. Results: Mort adverse experiences (AEs) were transient grade 1 or 2 events occurring during the treatment period. Clinically significant myelosuppression was not observed; hematologic toxicity was generally mild and reversible, No patient developed human antichimeric antibodies after treatment, The type, frequency, and severity of AEs in this study were not apparently differ-ent from those reported in the phase III trial of rituximab, The overall response rate in 57 assessable patients was 40% (11% complete response and 30% partial responses), Median time to progression (TTP) in responders and median duration of response (DR) have not been reached, but Kaplan-Meier estimated medians are 17.8 months (range, 5.4+ to 26.6 months) and 16.3 months (range, 3.71+ to 25.1 months), respectively. These estimated medians are longer than the medians achieved in the patients' prior course of rituximab (TTP and DR of 12.4 and 9.8 months, respectively, P >.1) and in a previously reported phase III trial (TTP in responders and DR of 13.2 and 11.6 months, respectively). Responses are ongoing in seven of 23 responders. Conclusion: In this re-treatment population, safety and efficacy were not apparently different from those after initial rituximab exposure. (C) 2000 by American Society of Clinical Oncology.