Continuous or Fixed-Duration Maintenance Therapy in Multiple Myeloma

BACKGROUND: Current treatment of newly diagnosed multiple myeloma involves lenalidomide maintenance therapy given until disease progression. The appropriate duration of maintenance therapy with lenalidomide has been unclear. METHODS: In this phase 3 trial, we enrolled patients with standard-risk newly diagnosed multiple myeloma who were not undergoing up-front autologous stem-cell transplantation. After induction treatment with a proteasome inhibitor-lenalidomide combination, patients were randomly assigned to receive indefinite-duration (continuous) lenalidomide or fixed-duration lenalidomide (for 2 years). The primary end point was overall survival; the trial had 80% power to detect a 50% increase in median survival (from 5 years to 7.5 years), with a two-sided alpha level of 5%, 395 patients undergoing randomization, and 204 deaths occurring during 9 years of follow-up. RESULTS: At the end of induction, 516 patients were randomly assigned to the indefinite-duration group (260 patients) or the fixed-duration group (256 patients). At a median follow-up of 86 months, overall survival did not differ significantly between the groups. With 80 deaths in each group, overall survival at 7 years was 68.6% in the indefinite-duration group and 69.0% in the fixed-duration group (difference, -0.4 percentage points; 95 confidence interval [CI], -9.0 to 8.3; P = 0.93). Progression-free survival at 7 years was 36.1% in the indefinite-duration group and 29.7% in the fixed-duration group (difference, 6.4 percentage points; 95% CI, -2.6 to 15.4). The 5-year cumulative incidence of second primary cancers, excluding nonmelanoma skin cancer, was 11.2% with indefinite-duration lenalidomide and 8.3% with fixed-duration lenalidomide. More adverse events occurred with indefinite-duration lenalidomide; the incidence of nonhematologic events of grade 3 or higher was 48.2% with indefinite-duration therapy and 31.5% with fixed-duration therapy. CONCLUSIONS: In this phase 3 trial involving patients with standard-risk newly diagnosed multiple myeloma who were not undergoing up-front autologous stem-cell transplantation, indefinite-duration maintenance therapy after induction therapy did not result in significantly longer overall survival than fixed-duration maintenance therapy. (Funded by the National Cancer Institute of the National Institutes of Health and Amgen; ENDURANCE ClinicalTrials.gov number, NCT01863550.).