Phase 2, multicenter GIBB study of obinutuzumab plus bendamustine in previously untreated patients with chronic lymphocytic leukemia

The single-arm, multicenter, phase 2 GIBB study (NCT02320487) investigated bendamustine plus obinutuzumab (BG) in previously untreated CLL. Patients (N = 102) received six cycles of intravenous obinutuzumab (cycle [C] 1: 100 mg day 1/900 mg day 2, and 1000 mg days 8/15; C2–6 1000 mg day 1) plus bendamustine (C1 90 mg/m² days 2/3; C2–6 days 1/2). Complete response (CR), the primary endpoint, was 50%, overall response 89%. Estimated 2-year progression-free survival (PFS) and overall survival (OS) were 86% and 97%, respectively. Following initial minimal residual disease (MRD) negativity, median MRD negativity duration was 28.9 months. Undetectable MRD (<10⁻⁴) was observed in up to 83% of evaluable patients in peripheral blood (any time) and 59% in bone marrow at response evaluation. Most common grade 3/4 adverse events (AEs) were neutropenia (25%; 5% febrile) and infusion-related reactions (9%). BG proved clinically active in CLL with high response, MRD negativity, and survival rates, consistent with other first-line studies of anti-CD20 antibody/bendamustine combinations.