This phase II trial investigated the safety and
efficacy of retreatment with rituximab (Rituxan) in patients with
low-grade or follicular non-Hodgkins lymphoma who relapsed
following a response to rituximab therapy. A total of 60 patients
received 375 mg/m² of rituximab every week × 4 doses
(intravenous [IV] infusion). Of the 60 patients, 5% had lymphomas
classified as International Working Formulation (IWF) A; 45%, IWF B;
47%, IWF C; and 3%, IWF D. All patients had received at least two
prior therapies and at least one prior course of rituximab.
Most adverse experiences were transient and grade 1 or 2. Significant
myelosuppression was not observed; hematologic toxicity was generally
mild and reversible. All patients remained CD20 positive, and none
developed human antichimeric antibody (HACA). The type, frequency,
and severity of adverse events were not apparently different from
those reported in other rituximab studies.
The overall response rate (ORR) in 57 evaluable patients was 40%.
Medians for time to progression (TTP) in responders and duration of
response (DR) have not been reached; Kaplan-Meier estimates are 16.7+
months (range, 3.7+ to 25.1 months) and 15.0+ months (range, 5.4 to
26.6 months), respectively, and are longer than the medians achieved
in these patients prior course of rituximab (TTP and DR of 12.4
and 9.8 months, respectively). Responses are ongoing in 6 of 23 responders.
CONCLUSION: This study shows that patients can be treated safely and
effectively with multiple courses of rituximab without induction of
human antichimeric antibody (HACA) and without the myelosuppression
common after multiple courses of chemotherapy. In this retreated
population, safety and efficacy were not apparently different than
are seen following initial rituximab exposure.