Four‐year follow‐up of a single arm, phase II clinical trial of ibrutinib with rituximab (IR) in patients with relapsed/refractory mantle cell lymphoma (MCL)

Summary Ibrutinib has shown significant activity in patients with relapsed or refractory mantle cell lymphoma ( RR ‐ MCL ). We report the long‐term outcome and safety profile of a single‐centre, single arm, open‐label, phase 2 study of RR ‐ MCL treated with IR . Overall, the median follow‐up time was 47 months (range 1–52 months), median duration on treatment was 16 months (range 1–53 months) and median number of treatment cycles was 17 (range 1–56). Twenty‐nine patients (58%) achieved complete remission and of these, 12 patients continue on study. Thirty‐eight patients discontinued treatment, 14 due to disease progression (2 transformed). Patients with blastoid morphology, high risk MCL International Prognostic Index score and high Ki67% had inferior survival. The commonest grade 1–2 toxicities were fatigue, diarrhoea, nausea, arthralgias and myalgias. None had long term toxicities. Median progression‐free survival was 43 months. Eighteen patients (36%) died (14 deaths were MCL ‐related). The median overall survival has not been reached. Treatment with IR can provide durable remissions in a subset of patients with RR ‐ MCL , especially those with low Ki67%. The possible benefit of adding other therapies in combination with IR in RR ‐ MCL is under exploration.