A Biologic Combination of Lenalidomide and Rituximab for Front-Line Therapy of Indolent B-Cell Non-Hodgkin's Lymphoma.

Abstract 1714 Poster Board I-740 Background Despite advances in therapy and a better understanding of the natural history of indolent non-Hodgkins lymphomas (NHL), the optimal treatment for newly diagnosed patients (pts) has not been determined. While several chemotherapy regimens have response rates approaching 90%, toxicity is common with standard genotoxic combinations, particularly with retreatment at relapse. Lenalidomide is approved for the treatment of relapsed/refractory multiple myeloma and myelodysplastic syndromes with del(5q) mutation. In pts with indolent relapsed or refractory NHL, treatment with lenalidomide resulted in durations of response lasting > 16.5 months (Witzig et al JCO in press). Rituximab has been shown to have clinical activity in indolent NHL, both as a single agent and in combination with chemotherapy. The aim of this phase II, single arm study is to evaluate the efficacy and safety of lenalidomide and rituximab in pts with untreated, stage III or IV, indolent NHL. Methods Previously untreated pts with indolent NHL and with measurable disease (>1.5 cm), were eligible for enrollment. For each 28-day cycle, pts received lenalidomide 20mg orally once daily on days 1-21 and rituximab 375mg/m2 intravenously on day 1, for up to 6 cycles of therapy. Response was assessed after 3 cycles and at the end of therapy using the International Working Group Response Criteria (Cheson et al 1999). Results At the time of this report, the planned accrual of 30 pts is complete. Response and adverse events are reported for the first 20 patients, which included 19 pts eligible for response assessment and 1 patient, who discontinued from study prior to response evaluation, secondary to leukocytoclastic vasculitis, which occurred during cycle 1. The median age was 55 yrs (range: 38-77) and 55% were male. The 20 currently evaluable patients include10 pts with follicular lymphoma, 8 pts with marginal zone lymphoma and 2 pts with small lymphocytic lymphoma. Of 19 pts eligible for response assessment, 18 completed 6 cycles of therapy and 1 pt, who was previously treated for Hodgkin's lymphoma, withdrew consent following cycle 3. The overall response rate was 84%, which included complete responses in 15 pts (79%; 58% CR/21% CRu) and 1 patient who achieved a partial response. An additional 3 pts (16%) remain with stable disease. By completion of 6 cycles of therapy, all 10 pts with follicular lymphoma achieved a complete response to therapy. No pt experienced progression of disease. The following grade 3/4 adverse events were reported; rash (6 pts), neutropenia (4 pts), myalgia (3 pts), neuropathy (1 pt), infection (1 pt), and fatigue (1 pt). Rashes, of all grades, occurred in 10 pts, which were mostly erythematous and transient, nonrecurring events. Response and toxicity assessment for the remaining 10 pts is ongoing and will be reported. Conclusion The biologic regimen of lenalidomide and rituximab as front line therapy produces excellent overall and complete response rates in pts with indolent B cell NHL. The combination was well tolerated with a manageable toxicity profile. Disclosures Fowler: Genentech: Honoraria, Speakers Bureau; BiogenIdec: Honoraria. Off Label Use: lenalidomide and rituximab for indolent B cell non-Hodgkin's lymphoma. McLaughlin:Genentech: Consultancy, Honoraria. Hagemeister:Genentech: Honoraria, Speakers Bureau; BiogenIdec: Honoraria, Speakers Bureau; Celgene: Consultancy. Kwak:Celgene: Research Funding. Samaniego:Celgene: Consultancy.