Interim results from a dose-escalation study of the BCL-2 inhibitor venetoclax (ABT-199/GDC-0199) plus bendamustine (B) and rituximab (R) in patients (pts) with relapsed/refractory (R/R) Non-Hodgkin's Lymphoma (NHL).

8535 Background: Venetoclax (VEN) is a selective, potent, orally bioavailable BCL-2 inhibitor that has shown single agent activity in R/R NHL. The current study evaluates VEN with BR, an active regimen widely used for NHL. Methods: Objectives were safety, PK, preliminary efficacy, MTD, and recommended Phase 2 dose. Dose escalation (DE) used a 3+3 design on a 28 day (d) cycle (C) with 3 VEN (50–400 mg) schedules: 3, 7, and 28 d/C. The BR regimen was 6 C: B (2 d/C, 90mg/m2) and R (1 d/C, 375mg/m2). DLTs for DE were assessed during C1. Responses were first assessed on C3 d1. Pts who completed VEN + BR with continued tolerability and without disease progression could continue VEN monotherapy up to 2 yrs. Results: As of 1/9/15, 33 were treated: 20 (61%) FL, 10 (30%) DLBCL, and 3 (9%) MZL. Median age was 62 (29-90) yrs. All had prior R or R-combination, of which 32 (97%) had R-based chemotherapy and 8 (24%) had prior B or BR. 16 (48%) pts are active; 17 discontinued (12 PD, 2 AE, 1 each withdrew consent, non-co...