Long Term Outcome of Lenalidomide-Dexamethasone (Rd) Vs Melphalan-Lenalidomide-Prednisone (MPR) Vs Cyclophosphamide-Prednisone-Lenalidomide (CPR) As Induction Followed By Lenalidomide-Prednisone (RP) Vs Lenalidomide (R) As Maintenance in a Community-Based Newly Diagnosed Myeloma Population: Updated Analysis of EMN01 Phase III Study

Introduction : Rd and MPR showed to be effective combinations in elderly newly diagnosed multiple myeloma (NDMM) patients (pts). Cyclophosphamide is a less toxic alkylating alternative agent. EMN01 is the first trial to formally compare these three different Lenalidomide-based combinations. Maintenance with Lenalidomide has been recently approved in patients eligible for autologous stem cell transplant (ASCT). Few data are available about the best combination as maintenance in patients not eligible for ASCT.

Methods : 662 pts with NDMM were randomized to receive 9 28-day cycles of Rd (lenalidomide 25 mg/day for 21 days; dexamethasone 40 mg on days 1,8,15 and 22 in pts 65-75 years old and 20 mg in those >75 years), MPR (lenalidomide 10 mg/day for 21 days; melphalan orally 0.18 mg/Kg for 4 days in pts 65-75 years old and 0.13 mg/Kg in >75 years pts; prednisone 1.5 mg/Kg for 4 days) or CPR (lenalidomide 25 mg/day for 21 days; cyclophosphamide orally 50 mg/day for 21 days in pts 65-75 years old and 50 mg every other day in >75 years pts; prednisone 25 mg every other day). After induction, pts were randomized to receive maintenance with lenalidomide alone (R; 10 mg/day for 21 days) or with prednisone (RP; R, 10 mg/day for 21 days and P, 25 mg every other day), until disease progression.

Results : Pts characteristics were well balanced in all groups; 217 pts in Rd, 217 in MPR and 220 in CPR arms could be evaluated. After a median follow-up of 63.7 months, median PFS was 23.2 months in MPR, 18.9 months in CPR and 18.6 months in Rd (MPR vs CPR p=0.02; MPR vs Rd p=0.08). Median overall survival (OS) was 79.9 months in MPR, 69.4 months in CPR and 68.1 months in Rd (MPR vs CPR p=0.98; MPR vs Rd p=0.64). The most common grade ≥3 adverse event (AEs) was neutropenia: 64% in MPR, 29% in CPR and 25% in Rd pts (p<0.0001). Grade ≥3 non hematologic AEs were similar among arms. At the end of induction, 402 pts were eligible for maintenance, 198 in the RP and 204 in the R groups. PFS from start of maintenance was 22.2 months in the RP group and 17.6 in the R group, with 20% reduced the risk of death/progression for pts receiving RP maintenance (HR 0.81, p=0.07; Figure 1). A subgroup analysis was performed to determine the consistency of RP vs R treatment effect in different subgroups using interaction terms between treatment and cytogenetic abnormalities, ISS, age, sex, induction treatment and response before maintenance (Figure 1). No difference in OS was observed (HR 1.02, p=0.93) but the OS analysis was limited by the low number of events. Median duration of maintenance was 23.0 months in RP pts and 20.5 months in R pts, 14% and 13% of pts discontinued due to AEs, in RP and R groups, respectively.

Conclusion : This phase III trial compared 2 different Lenalidomide-containing induction regimens and 2 different Lenalidomide-containing maintenance regimens in an elderly community-based NDMM population. MPR prolonged PFS by approximately 5 months, yet the higher incidence of hematologic toxicity should be carefully considered. The addition of low-dose prednisone to standard lenalidomide maintenance reduced the risk of death/progression by 20%, with a good safety profile. Updated results will be presented at the meeting.

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