The phase 2 GRIFFIN study of daratumumab plus lenalidomide/bortezomib/dexamethasone (D-RVd) for transplant-eligible, newly diagnosed multiple myeloma included a safety run-in phase followed by a randomized phase. The ongoing randomized phase has met its prespecified primary end point of an improved stringent complete response (sCR) rate after consolidation for D-RVd (reported elsewhere). Final analysis of the safety run-in cohort is reported herein and provides longer follow-up (median, 40.8 months) encompassing daratumumab plus lenalidomide (D-R) maintenance therapy. Patients in the safety run-in cohort (N 5 16) received 4 induction cycles (D-RVd), high-dose melphalan supported by autologous stem cell transplant, 2 consolidation cycles (D-RVd), and 24 months of maintenance (D-R). By the end of consolidation, all patients had responded, with a best response of sCR in 9 (56.3%) patients; 8 (50.0%) patients were minimal residual disease (MRD) negative (10?5 threshold). After maintenance, 15 (93.8%) patients had achieved a best response of sCR, and 13 (81.3%) patients were MRD (10?5) negative. Estimated 36-month progression-free and overall survival rates were 78.1% and 93.8%, respectively. One death from progressive disease occurred in the patient who did not achieve sCR. Observed safety profiles were consistent with daratumumab and RVd. With .3 years of median follow-up, D-RVd achieved durable responses that deepened with D-R maintenance. This study was registered at www.clinicaltrials.gov as #NCT02874742.