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=0.04), in Rd-R versus continuous Rd, respectively (Figure 1).

Best response rates were not significantly different between the 2 groups: ≥PR rates were 73% vs 63%, and ≥VGPR rates were 43% vs 35% in the Rd-R vs Rd continuous group, respectively (p=ns).

No difference in progression-free survival (PFS) and overall survival (OS) was observed. Median PFS was 18.3 vs 15.5 months (HR 0.93, 95% CI 0.64-1.34, p=ns) (Figure 1), 18 month-OS was 85% versus 81% (HR 0.73, 95% CI 0.40-1.33, p=ns).

Adverse events accounting for EFS (any hematologic grade 4, non-hematologic grade 3-4) were less frequent in the Rd-R group (30% vs 39%) than in the continuous Rd group (p=ns). The most frequent adverse events were neutropenia, infection and skin reactions (less than 10% in each arm). After 9 treatment cycles, these adverse events were less frequent in Rd-R vs continuous Rd group (3% vs 7%, p=ns).

Lenalidomide dose reduction after 9 treatment cycles was required in 1% of Rd-R patients and 21% of continuous Rd patients (p =0.06). Dexamethasone dose reduction was required in 17% vs 29% of patients, respectively (p=0.06).

CONCLUSION: This is the first prospective randomized phase III trial specifically designed for real-life intermediate-fit NDMM patients. A dose/schedule-adjusted Rd-R treatment was more feasible compared to full dose continuous Rd treatment in elderly intermediate-fit NDMM patients, with no negative impact but rather a comparable outcome. These results confirm the need for an appropriate definition of patient frailty, and pave the way to a frailty-adjusted treatment approach to better balance efficacy and safety in elderly NDMM patients.

Figure 1.

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Figure 1.

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