Single-Agent Ibrutinib for Rituximab-Refractory Waldenström Macroglobulinemia: Final Analysis of the Substudy of the Phase III InnovateTM Trial
Judith Trotman, Christian Buske, Alessandra Tedeschi, Jeffrey Matous, D. Blair Macdonald, Constantine S. Tam, Olivier Tournilhac, Shuo Ma, Steven P. Treon, Albert Oriol, Jerry Ping, Eva M. Briso, Israel Arango‐Hisijara, Meletios Α. Dimopoulos
Abstract
PURPOSE: The first report from the open-label substudy of the phase III iNNOVATE study (PCYC-1127; NCT02165397) demonstrated that single-agent ibrutinib was efficacious and well tolerated in patients with heavily pretreated, rituximab-refractory Waldenström macroglobulinemia. Results from the final analysis are now reported. PATIENTS AND METHODS: = 31) who failed to achieve at least a minor response (MR) or who relapsed <12 months after their last rituximab-containing therapy. Endpoints included progression-free survival (PFS) and overall response rate (ORR; MR or better) per independent review committee, hemoglobin improvement, overall survival (OS), and safety; serum IgM was also assessed. RESULTS: subtypes, median PFS was 18 months and not reached, respectively. In all patients, ORR was 87%; responses deepened over time with major response (≥ partial response) rates increasing from 61% at 6 months to 77% at 60 months. Median OS was not reached. Seventeen of 21 patients (81%) with baseline hemoglobin ≤11.0 g/dL had sustained hemoglobin improvement. Improvements in serum IgM levels were sustained, reaching a maximum median change of -37 g/L at 54 months. Ibrutinib maintained a manageable safety profile, with no new safety signals identified. There were no events of major hemorrhage or atrial fibrillation. CONCLUSIONS: In the final analysis from iNNOVATE, single-agent ibrutinib continued to show sustained efficacy in patients with heavily pretreated, rituximab-refractory Waldenström macroglobulinemia.