Rituximab/bendamustine and rituximab/cytarabine induction therapy for transplant-eligible mantle cell lymphoma

The addition of high-dose cytarabine to rituximab/bendamustine (RB) induction could improve outcomes for transplant-eligible patients with mantle cell lymphoma (MCL). We conducted a pooled analysis of 2 phase 2 trials and an off-trial cohort each testing 3 cycles of RB and 3 cycles of rituximab/high-dose cytarabine (RC) followed by autologous stem cell transplantation (ASCT) among untreated, transplant-eligible patients with MCL. Dana-Farber Cancer Institute (DFCI) and Washington University in St. Louis (WUSTL) led separate phase 2 trials testing sequential and alternating cycles of RB/RC, respectively. Patients treated at DFCI with sequential RB/RC off trial were retrospectively identified. Minimal residual disease (MRD) was assessed in the DFCI trial. A total of 88 patients (23 DFCI trial, 18 WUSTL trial, and 47 off trial) received RB/RC; 92% of patients completed induction, and 84% underwent planned consolidative ASCT. Grade 3 or 4 adverse events among trial patients included lymphopenia (88%), thrombocytopenia (85%), neutropenia (83%), and febrile neutropenia (15%). There were no treatment-related deaths during induction and 2 following ASCT. Among 87 response-evaluable patients, the end-of-induction overall and complete response rates were 97% and 90%, respectively. After a median follow-up of 33 months, 3-year progression-free survival and overall survival were 83% and 92%, respectively. Patients undergoing MRD testing experienced prolonged MRD negativity after ASCT with emergence of MRD occurring in only 1 patient who subsequently relapsed. RB/RC followed by ASCT achieves high rates of durable remissions in transplant-eligible patients with MCL. These trials were registered at www.clinicaltrials.gov as #NCT01661881 (DFCI trial) and #NCT02728531 (WUSTL trial).