The approval was based on safety and efficacy results from Phase III studies, including the FIRST trial (MM-020/IFM 07-01), which evaluated continuous Revlimid in combination with dexamethasone (Rd Continuous) until disease progression versus melphalan, prednisone and thalidomide (MPT) for 18 months as the primary analysis, and a fixed duration of 18 cycles of Rd (Rd18) as a secondary analysis, in 1,623 newly diagnosed patients who were not candidates for stem cell transplant. PFS was significantly longer for patients receiving Rd Continuous (25.5 months) than for those treated with MPT (21.2 months). Median overall survival (OS) in the two groups was 58.9 months and 48.5 months, respectively based on a March 3, 2014 interim OS analysis. Patients in the Rd Continuous arm had a 25% reduction in the risk of death compared to patients in the MPT arm.