Observational study of lenalidomide in patients with mantle cell lymphoma who relapsed/progressed after or were refractory/intolerant to ibrutinib (MCL-004)

Background: The observational MCL-004 study evaluated outcomes in patients with relapsed/refractory mantle cell lymphoma who received lenalidomide-based therapy after ibrutinib failure or intolerance. Methods: The primary endpoint was investigator-assessed overall response rate based on the 2007 International Working Group criteria. Results: Of 58 enrolled patients (median age, 71 years; range, 50-89), 13 received lenalidomide monotherapy, 11 lenalidomide plus rituximab, and 34 lenalidomide plus other treatment. Most patients (88%) had received ≥ 3 prior therapies (median 4; range, 1-13). Median time from last dose of ibrutinib to the start of lenalidomide was 1.3 weeks (range, 0.1-21.7); 45% of patients had partial responses or better to prior ibrutinib. Primary reasons for ibrutinib discontinuation were lack of efficacy (88%) and ibrutinib toxicity (9%). After a median of two cycles (range, 0-11) of lenalidomide-based treatment, 17 patients responded (8 complete responses, 9 partial responses), for a 29% overall response rate (95% confidence interval, 18-43%) and a median duration of response of 20 weeks (95% confidence interval, 2.9 to not available). Overall response rate to lenalidomide-based therapy was similar for patients with relapsed/progressive disease after previous response to ibrutinib (i.e., ≥PR) versus ibrutinib-refractory (i.e., ≤SD) patients (30 versus 32%, respectively). The most common all-grade treatment-emergent adverse events after lenalidomide-containing therapy (n = 58) were fatigue (38%) and cough, dizziness, dyspnea, nausea, and peripheral edema (19% each). At data cutoff, 28 patients have died, primarily due to mantle cell lymphoma. Conclusion: Lenalidomide-based treatment showed clinical activity, with no unexpected toxicities, in patients with relapsed/refractory mantle cell lymphoma who previously failed ibrutinib therapy. Trial registration: Clinicaltrials.gov identifier NCT02341781.