131 patients were enrolled between June 12, 2015, and Dec 6, 2018. The median age was 56 years (IQR 49–60). 58 (50%) of 117 patients had high Ki-67 (≥30%). 129 (98%, 95% CI 95–100) of 131 patients had an overall response in part A...Induction with ibrutinib–rituximab in the frontline treatment of young patients with mantle cell lymphoma is active and safe.