Efficacy and Feasibility of Dose/Schedule-Adjusted Rd-R Vs. Continuous Rd in Elderly and Intermediate-Fit Newly Diagnosed Multiple Myeloma (NDMM) Patients: RV-MM-PI-0752 Phase III Randomized Study

INTRODUCTION: Elderly patients with newly diagnosed multiple myeloma (NDMM) are highly heterogeneous and their outcome is influenced by many factors: beside age, also comorbidities, general physical fitness, and cognitive function play a crucial role. The IMWG frailty score combines age, functional status, and comorbidities, and it identifies fit, intermediate-fit and frail patients, with different risk of toxicity, treatment discontinuation, and mortality (Palumbo A et al. Blood 2015). Until now, evidence-based tailored treatments according to patients' frailty are still lacking. Therefore, this phase III study investigated the efficacy and feasibility of dose/schedule-adjusted lenalidomide-dexamethasone therapy followed by lenalidomide maintenance (Rd-R) versus continuous lenalidomide-dexamethasone (Rd) in elderly, intermediate-fit NDMM patients. METHODS: Intermediate-fit NDMM patients, with a total frailty score (age, Charlson Index, ADL and IADL) of 1 (http://www.myelomafrailtyscorecalculator.net/), were enrolled and randomized to receive Rd-R or continuous Rd. To better approximate a real-world older population, patients usually excluded from clinical trials or with abnormal laboratory values could be included in the trial. Rd-R treatment consisted of nine 28-day cycles of lenalidomide 25 mg/day for 21 days and dexamethasone 20 mg on days 1,8,15,22, followed by lenalidomide maintenance 10 mg/day for 21 days, until disease progression. Continuous Rd consisted of lenalidomide 25 mg/day for 21 days and dexamethasone 20 mg on days 1,8,15,22, until disease progression. The dose and schedule of continuous Rd was the one adopted in patients >75 years in the FIRST trial (Hulin C et al. JCO 2016). The primary endpoint was event-free survival (EFS), defined as progression or death for any cause or discontinuation of lenalidomide or occurrence of any hematological grade 4 or non-hematological grade 3-4 adverse events (AEs), including Secondary Primary Malignancies (SPMs), whichever came first. RESULTS: 199 patients (98 in Rd-R arm and 101 in continuous Rd arm) could be evaluated. Patients characteristics were well balanced between the 2 arms. Median age was 75 and 76 years (p=0.06); 47% in Rd-R vs 57% in continuous Rd were defined intermediate-fit for age (≥76 years), 53% vs 43% due to an impairment in Charlson Index, ADL or IADL (p=ns). In intention-to-treat analysis, after a median follow-up of 25 months, EFS was 9.3 vs 6.6 months (HR 0.72, 95% CI 0.52-0.99, p