Lenalidomide plus high-dose dexamethasone provides improved overall survival compared to high-dose dexamethasone alone for relapsed or refractory multiple myeloma (MM): Results of a North American phase III study (MM-009)

Abstract

7521 Background: Lenalidomide is a novel, orally administered, immunomodulatory drug (IMiD) that has single-agent activity against MM and additive effects when combined with dexamethasone (Dex). Methods: In this phase 3, multicenter, double-blind trial, 354 patients (pts)with relapsed or refractory MM were treated with Dex 40 mg daily on days 1–4, 9–12, 17–20 every 28 days and were randomized to receive either lenalidomide (Len) 25 mg daily orally on days 1–21 every 28 days or placebo. Beginning with cycle 5, Dex was reduced to 40 mg daily on days 1–4 only, every 28 days. Patients were stratified with respect to B2M (≤ 2.5 vs. > 2.5 mg/mL), prior stem cell transplant (none vs. ≥ 1), and number of prior regimens (1 vs > 1). The treatment arms were well balanced for prognostic features. Results: The overall response rate was greater with Len-Dex than with Dex-placebo (59.4% vs. 21.1%; p < 0.001). Complete responses were achieved in 12.9% of pts treated with Len-Dex and 0.6% of pts treated with Dex-placebo. The median time to progression (TTP) for pts treated with Len-Dex was 11.1 months compared to 4.7 months for pts treated with Dex-placebo (p < 0.000001). Median overall survival was higher with Len-Dex (not reached) compared to Dex-placebo (24 months) (hazard ratio 1.76, p = .0125). Grade 3–4 neutropenia was more frequent with combination therapy than with Dex-placebo (24% vs. 3.5%), however ≥ grade 3 infections were similar in both groups. Thromboembolic events occurred in 15% of pts treated with Len-Dex and in 3.5% of pts treated with Dex-placebo. Atrial fibrillation occurred in 8 pts and CHF developed in 4 pts treated with Len-Dex. Conclusions: Considering the ease of oral administration, higher response rate, longer time to progression and overall survival benefit, the combination of lenalidomide-dexamethasone may very well represent the treatment of choice for early refractory or relapsing multiple myeloma. The relatively infrequent side effects should not detract from these improvements, but the use of prophylactic antithrombotic therapy should be considered for patients treated with the combination of lenalidomide and dexamethasone. [Table: see text]