Ibrutinib maintenance after frontline treatment in patients with mantle cell lymphoma

Maintenance rituximab in mantle cell lymphoma (MCL) has improved survival and supports exploration of maintenance with novel agents. We evaluated the safety and efficacy of ibrutinib maintenance (I-M) after induction in patients with treatment-naive MCL. Patients with MCL with complete response (CR) or partial response to frontline chemoimmunotherapy ± autologous stem cell transplantation (auto-SCT) received I-M 560 mg daily for up to 4 years. Primary objective was 3-year progression-free survival (PFS) rate from initiation of I-M. Minimal residual disease (MRD) assessments by next-generation sequencing (NGS) on peripheral blood were measured before I-M initiation and at 1, 6, and 18 to 24 months after initiation. Among 36 patients, the median age was 60 years (range, 46-90). For frontline treatment, 18 patients (50%) had consolidation with auto-SCT in CR1 before I-M. At median follow-up of 55.7 months, 17 patients (47%) completed full course I-M (median, 37.5 cycles; range, 2-52). The 3-year PFS and overall survival (OS) rates were 94% and 97%, respectively. With prior auto-SCT, 3-year PFS and OS rates were both 100%. The most common treatment-related adverse event with I-M was infection (n = 31; 86%), typically low grade; the most common grade 3/4 toxicities were hematologic. In 22 patients with MRD assessments, all were MRD negative after induction. Six became MRD positive on I-M, with 2 reverting to MRD-negative status with continued I-M, and all maintain radiographic CR with the exception of 1 with disease progression. I-M is feasible in MCL after frontline chemoimmunotherapy with manageable toxicities although significant. Changes in NGS-MRD were noted in limited patients during maintenance with few progression and survival events. This trial was registered at www.clinicaltrials.gov as #NCT02242097.