Safety and efficacy of acalabrutinib plus bendamustine and rituximab in patients with treatment-naive or relapsed / refractory mantle cell lymphoma: phase Ib trial

This multicenter, open-label, phase Ib study (ACE-LY-106) assessed the safety and efficacy of acalabrutinib, bendamustine, and rituximab (ABR) in treatment-naïve (TN) and relapsed or refractory (R/R) mantle cell lymphoma (MCL). Patients received acalabrutinib from cycle 1 until disease progression or treatment discontinuation, bendamustine on days 1 and 2 of each cycle for up to 6 cycles, and rituximab on day 1 of each cycle for 6 cycles, continuing every other cycle from cycle 8 for 12 additional doses (TN cohort). Eighteen patients enrolled in the TN cohort and 20 in the R/R cohort. Median duration of exposure to acalabrutinib was 34.0 and 14.6 months in the TN and R/R cohorts, respectively. No new safety risks were identified, and most adverse events (AE) were grades 1 or 2. Thirteen patients from the TN cohort (72.2%) and 17 patients from the R/R cohort (85.0%) reported grade 3-4 AE, most commonly neutropenia (TN: 38.9%; R/R: 50.0%). AE leading to death were pneumonitis (N=1, TN cohort), COVID-19, and cerebrospinal meningitis (N=1 each, R/R cohort). Overall response was 94.4% and 85.0% in the TN and R/R cohorts, respectively; complete response rates were 77.8% and 70.0%, respectively. After a median follow-up of 47.6 months, median progression-free survival (PFS) and overall survival (OS) were not reached in the TN cohort. After a median follow-up of 20.4 months, median PFS was 28.6 months and OS was not reached in the R/R cohort. Results indicate that ABR was safe and efficacious, supporting further study in patients with TN MCL.