Pre-Transplant Rituximab Plus Bendamustine Leads to High Remission Rates in MCL

Administering rituximab plus bendamustine before autologous stem cell transplantation (ASCT) in transplant-eligible patients with mantle cell lymphoma (MCL) led to high rates of durable remission in a pooled analysis by Reid W. Merryman, MD, Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, et al (Blood Adv. 2020;4[5]:858-867).

“The addition of high-dose cytarabine to rituximab/bendamustine…induction could improve outcomes for transplant-eligible patients with [MCL],” explained Dr Merryman and colleagues, who pooled and analyzed data from 2 phase 2 trials and an off-trial cohort examining the use of 3 cycles of rituximab plus bendamustine and 3 cycles of rituximab plus high-dose cytarabine followed by ASCT in treatment-naïve, transplant-eligible patients with MCL.

The phase 2 clinical trials were led by Dana-Farber Cancer Institute (DFCI) and Washington University in St. Louis (WUSTL) and evaluated sequential and alternating cycles of rituximab plus bendamustine and rituximab plus high-dose cytarabine, respectively.

Dr Merryman et al also retrospectively identified patients treated with sequential rituximab plus bendamustine and rituximab plus high-dose cytarabine off trial at DFCI. In the DFCI trial, investigators evaluated minimal residual disease (MRD).

Ultimately, 88 patients (including 23 in the DFCI trial, 18 in the WUSTL trial, and 47 off-trial) were given rituximab plus bendamustine and rituximab plus high-dose cytarabine, with 92% completing induction and 84% undergoing consolidative ASCT.

Grade 3 or 4 lymphopenia (88%), thrombocytopenia (85%), neutropenia (83%), and febrile neutropenia (15%) were frequently observed adverse events among trial patients. Although no treatment-related deaths occurred during induction, 2 were reported after ASCT.

In 87 patients with evaluable responses, end-of-induction overall and complete response rates were 97% and 90%, respectively. With a median follow-up of 33 months, 3-year progression-free survival and overall survival rates were found to be 83% and 92%, respectively.

Furthermore, patients who underwent MRD testing had prolonged MRD-negativity after ASCT; MRD emergence occurred in only 1 patient whose disease subsequently relapsed.

“In our pooled analysis, [rituximab plus bendamustine] induction followed by ASCT was associated with high rates of durable remissions in transplant-eligible patients with MCL,” Dr Merryman and co-investigators concluded.—Hina Porcelli