Time-Limited Bendamustine, Rituximab, and Venetoclax (BR-VR) in Untreated Chronic Lymphocytic Leukemia (CLL): High Rates of Undetectable Minimal Residual Disease Remissions

Background: Despite the efficacy of venetoclax (VEN) in frontline CLL, optimal combination regimens and duration of treatment remain unclear. We hypothesized that cytoreduction with bendamustine/rituximab (BR) induction followed by venetoclax/rituximab (VR) consolidation for a fixed 1-year duration would be associated with an increased rate of undetectable minimal residual disease (uMRD) compared to historical controls and a reduction in the risk of tumor lysis syndrome (TLS). Here we report updated data from a fully-enrolled ongoing phase 2 multicenter, US, single-arm, open-label study (NCT03609593) designed to assess the safety and efficacy of BR-VR in previously untreated CLL patients (pts). Methods: Previously untreated CLL/SLL pts ≥ 18 years requiring therapy per iwCLL criteria initially received 3 cycles of bendamustine 50-90 mg/m 2 daily for 2 days and rituximab 375 mg/m 2 every 28 days for 3 cycles. Following BR, VEN was initiated with a standard dose escalation from 20 mg to 400 mg daily over 5 weeks. This was followed by 6 cycles of VR with rituximab given monthly and 5 cycles of VEN alone (12 cycles of VEN in total). Additional eligibility included: ECOG PS ≤ 2, hemoglobin ≥8g/dL, ANC ≥1000/mm 3, and platelets ≥50,000/mm 3. Response was assessed by 2018 iwCLL criteria with uMRD testing by central flow cytometry at a level of