Updated results of a phase I first-in-human study of the BCL-2 inhibitor ABT-199 (GDC-0199) in patients with relapsed/refractory non-Hodgkin lymphoma (NHL).

Abstract

8520 Background: BCL-2 is highly expressed in NHL, including mantle cell lymphoma (MCL), and is a promising therapeutic target as it is involved in NHL pathogenesis and mediates resistance to many cytotoxics. ABT-199 is a second generation inhibitor with 500-fold higher affinity for BCL-2 (Ki<0.10 nM) than BCL-XL (Ki=48 nM). Methods: Objectives of this Ph 1 dose-escalation study include evaluations of safety, pharmacokinetics and preliminary efficacy in patients (pts) with relapsed or refractory (R/R) NHL. A single oral dose (50-400 mg) was administered followed by 6 days off drug prior to the initiation of continuous once daily dosing. Due to concerns of potential tumor lysis syndrome (TLS), a 2 to 3 wk lead-in period with step-wise escalation to the target cohort dose was implemented. Dose cohorts up to 900 mg have been evaluated to date. Results: As of January 2013, 31 pts have been enrolled (median age 68 y (range 35-85); 20 males; median prior therapies 3 (range 1-7). 13 (42%) and 4 (13%) had bulky adenopathy (>5 and >10 cm, respectively). The most common AEs (≥15% of patients) were nausea (36%), diarrhea (26%), dyspepsia, vomiting, fatigue, pyrexia and cough (16% each). Gr 3/4 AEs occurring in >1 patient were anemia, neutropenia (4 pts each), and febrile neutropenia (2 pts). Two of 14 pts in cohort 5 experienced DLTs at the target dose of 600 mg: Gr 3 febrile neutropenia and Gr 4 neutropenia. Although Gr 3/4 thrombocytopenia was observed in 3 pts, it was not dose dependent. Gr 3 TLS was seen after the initial dose in 1 pt with very bulky MCL (>10 cm). With a median follow-up of 5 months (range 0.5-15), 17 have discontinued: 13 due to PD, 2 due to AEs and 2 who received a BMT. Of the 29 pts evaluable for efficacy, the overall best response rate was 55% with 1 DLBCL pt achieving a CR and 15 (52%) a PR (8/8 MCL, 3/3 Waldenstrom macroglobulinemia, 2/7 follicular lymphoma and 2/7 DLBCL pts). Conclusions: ABT-199 is highly active in R/R NHL, particularly in MCL. Additional dosing and scheduling modifications are currently being explored to optimize the efficacy/safety profile of this active new agent. ABT-199 warrants further single-agent and combination trials in NHL. Clinical trial information: NCT01328626.