Although initial therapy of mantle cell lymphoma (MCL) is not standardized, bendamustine plus rituximab (BR) is commonly used in older patients. Rituximab (R) maintenance after induction is often used. Thus, the open-label, randomized phase 2 ECOG-ACRIN Cancer Research Group E1411 trial was designed to test 2 questions: (1) does addition of bortezomib to BR induction (BVR) and/or (2) addition of lenalidomide to rituximab (LR) maintenance improve progression-free survival (PFS) in patients with treatment-naïve MCL? From 2012 to 2016, 373 previously untreated patients, 87% aged ≥ 60 years, were enrolled in this trial. At a median follow-up of 7.5 years, there is no difference in the median PFS of BR compared with BVR (5.5 vs 6.4 years; hazard ratio [HR], 0.90; 90% confidence interval [CI], 0.70-1.16). There were no unexpected additional toxicities with BVR treatment compared with BR, with no impact on total dose/duration of treatment received. Independent of the induction treatment, addition of lenalidomide did not significantly improve PFS, with median PFS in R vs LR (5.9 vs 7.2 years; HR, 0.84; 90% CI, 0.62-1.15). Most patients completed the planned 24 cycles of LR at the scheduled dose. In summary, adding bortezomib to BR induction does not prolong PFS in treatment-naïve MCL, and LR maintenance was not associated with longer PFS compared with R alone after BR. Nonetheless, the >5-year median PFS outcomes in this prospective cooperative group trial indicate the efficacy of BR followed by R maintenance as highly effective initial therapy for older patients with MCL. This trial was registered at www.clinicaltrials.gov as #NCT01415752.