Introduction: The phase III RandomizEd, OpeN Label, Phase 3 Study of Carfilzomib Plus DExamethAsone Vs Bortezomib Plus DexamethasOne in Patients With Relapsed Multiple Myeloma (ENDEAVOR) trial showed significantly improved progression-free survival and overall survival (OS) with carfilzomib (56 mg/m) and dexamethasone (Kd56) versus bortezomib and Kd56 (Vd) in patients with relapsed or refractory multiple myeloma (RRMM). We report updated OS and safety data after 6 months of additional follow-up. Patients and Methods: Patients with RRMM (1-3 previous lines of therapy) were randomized 1:1 to Kd56 or Vd. Median OS was estimated using the Kaplan-Meier method; OS was compared between treatment groups using Cox proportional hazards models. Results: As of July 19, 2017, median follow-up was 44.3 months for Kd56 and 43.7 months for Vd. Median OS was 47.8 months (Kd56) versus 38.8 months (Vd; hazard ratio, 0.76; 95% confidence interval, 0.633-0.915). OS was longer with Kd56 versus Vd within age and cytogenetic subgroups, and according to number of previous lines of therapy, previous bortezomib exposure, previous lenalidomide exposure, and lenalidomide-refractory status. Exposure-adjusted incidences per 100 patient-years of adverse events (AEs) were 1352.07 for Kd56 and 1754.86 for Vd; for Grade ≥3 AEs, these values were 162.31 and 175.90. Conclusion: With median follow-up of approximately 44 months, clinically meaningful improvements in OS were observed with Kd56 versus Vd, including in all subgroups examined. The Kd56 safety profile was consistent with previous analyses. In this updated analysis of patients with relapsed/refractory multiple myeloma (RRMM) from the RandomizEd, OpeN Label, Phase 3 Study of Carfilzomib Plus DExamethAsone Vs Bortezomib Plus DexamethasOne in Patients With Relapsed Multiple Myeloma (ENDEAVOR) trial, clinically meaningful overall survival improvements continue to be observed with carfilzomib 56 mg/m and dexamethasone (Kd56; n = 464) versus bortezomib and dexamethasone (n = 465), including in key patient subgroups. With longer-term data, the favorable benefit-risk profile of Kd56 continues to support its use as a standard-of-care in RRMM.