A phase 1/1b study of rituximab, bendamustine, and ibrutinib in patients with untreated and relapsed/refractory non-Hodgkin lymphoma

Ibrutinib has single agent activity of 22% to 68% in relapsed B-cell non-Hodgkin lymphoma (NHL). This study evaluated the safety and efficacy of ibrutinib combined with rituximab (R) and bendamustine. Patients received R (375 mg/m(2)) on day 1, bendamustine (90 mg/m2) on days 1 and 2, and ibrutinib (280 or 560 mg) on days 1 to 28 every 28 days for 6 cycles followed by ibrutinib alone until progression. Forty-eight patients enrolled, including 12 patients with follicular lymphoma (FL), 16 with diffuse large B-cell lymphoma (DLCL), and 17 with mantle cell lymphoma (MCL). No dose-limiting toxicities were observed. Patients received a median of 8 cycles, with 26 completing 6 cycles and continuing ibrutinib alone in cycles 7 to 34. The overall response (OR) rate was 72%, with 52% complete responses (CRs). By histology, the OR rate was 94% (76% CR) in MCL, 37% (31% CR) in DLCL, and 90% (50% CR) in FL. Grade 3 to 4 toxicities included lymphopenia (77%), neutropenia (33%), thrombocytopenia (19%), and rash (25%). Median progression-free survival has not been reached (95% CI, 8.7 months to not reached). The recommended phase 2 dose of ibrutinib in combination with R-bendamustine in patients with NHL is 560 mg. The combination has promising efficacy, particularly in MCL and FL. This trial was registered at www.clinicaltrials.gov as #NCT01479842.