A multicenter phase II study of bendamustine with rituximab in patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL).

Abstract

8023 Background: Effective salvage therapies are needed in patients (pts) with relapsed/refractory DLBCL after R-CHOP. Therapy with bendamustine plus rituximab (B-R) was well tolerated and effective in the preceding phase I study in relapsed/refractory aggressive B-cell non-Hodgkin lymphoma, including DLBCL. This phase II study assessed the efficacy and safety of B-R in pts with relapsed/refractory DLBCL. Methods: Pts with histologically confirmed DLBCL (excluding transformed disease) and 1-3 prior therapies received rituximab 375 mg/m2 IV on day 1 and bendamustine 120 mg/m2 IV on days 2 and 3 of each 21-day cycle, for up to 6 cycles. Recovery of neutrophil count to ≥1,000/mm3 and platelet count to ≥75,000/mm3 were required prior to the start of each cycle; treatment delays >2 weeks resulted in discontinuation. The primary endpoint was overall response rate (ORR); secondary endpoints included complete response (CR) rate, progression-free survival (PFS), and safety. Results: A total of 63 pts were enrolled; data from 59 pts were available. Median age was 67 (range, 36-75) years with 37 pts over 65 years. The majority of pts (64.4%) had 1 prior therapy; 57 pts (96.6%) were previously treated with rituximab-containing combination chemotherapy and 8 (13.6%) had prior auto-PBSCT. Pts received a median of 4 (range, 1-6) treatment cycles. Sixteen (27.1%) pts completed 6 treatment cycles; most common reasons for early discontinuation were disease progression (n=15) and failure to meet criteria to start the next cycle (n=13). Among 59 pts evaluable for response, ORR was 62.7% with a 37.3% CR rate. The median PFS was 200 days (95% CI, 109-410). Most common grade 3/4 adverse events (AEs) included CD4 lymphocytes decreased (66.1%), neutropenia (54.2%), and thrombocytopenia (10.2%). Four (6.8%) pts discontinued due to serious AEs (cytomegalovirus infection, infection, pneumonia, and pneumonia/respiratory failure). Conclusions: B-R demonstrated promising activity in pts with relapsed/refractory DLBCL. Toxicity was primarily hematologic and generally manageable. These results suggest that B-R is a promising salvage regimen for pts with relapsed/refractory DLBCL after R-CHOP.