Lenalidomide and Dexamethasone Alone Is Equivalent To Lenalidomide and Dexamethasone With Autologous Stem Cell Transplant In Newly Diagnosed Multiple Myeloma: Interim Study Results Of a Randomized Trial

The current standard of care for patients with newly diagnosed multiple myeloma (MM) aged less than 65 years is high-dose chemotherapy combined with autologous stem cell transplantation (ASCT) based on improved progression free survival (PFS) and overall survival (OS) compared with conventional chemotherapy. The introduction of novel agents, for example lenalidomide and bortezomib over the last decade, has substantially improved MM outcomes providing similar response rates to ASCT. As a consequence, the role of upfront ASCT has become more controversial. Therefore, this randomized clinical trial aims to determine the role of upfront ASCT in patients with newly diagnosed MM patients receiving lenalidomide and low-dose dexamethasone as induction therapy.

Patients enrolled into the study were aged ≥18 years with newly diagnosed MM, transplant eligible, and meeting CRAB criteria. Patients were randomized to receive 4 cycles of lenalidomide (25 mg days 1–21) plus low-dose dexamethasone (40 mg days 1, 8, 15, 22) followed by ASCT conditioned with 200 mg/m² melphalan (Arm A; LD+ASCT) or 8 cycles of lenalidomide plus low-dose dexamethasone (Arm B; LD alone). Both groups received lenalidomide maintenance therapy 10-15 mg for up to 2 years. Patients in both treatment arms received stem cell collection after 4 cycles of lenalidomide plus dexamethasone if at least a partial response was achieved. Patients with stable disease or progressive disease (PD) went off study. The primary objective was to compare the best response between patients treated with lenalidomide plus dexamethasone followed by ASCT and patients treated with lenalidomide plus dexamethasone alone. Secondary objectives were to compare the duration of response (DOR), PFS, and OS between the two treatment arms and to evaluate the secondary malignancies in both arms.

Fifty patients with newly diagnosed MM were randomized between February 2008 and May 2013, and 47 patients were eligible for evaluation in this interim analysis; 25 patients randomized to Arm A (LD+ASCT) and 22 patients randomized to Arm B (LD alone). Overall, patients had a median age of 61.6 years (range 48–75), 60% were male, 34% ISS Stage I, 49% ISS Stage II, 17% ISS Stage III. The data were analyzed according to the IMWG response criteria (Blood. 2011 May 5;117(18):4691-5). In an intention-to-treat analysis, there was a trend towards improved overall response rate (ORR) in patients receiving LD+ASCT (96%) compared with patients receiving LD alone (77%; p=0.08) (Table 1). After a median follow-up of 36.8 months (range 1.1–62.7), the median DOR was 13.9 months (95% confidence interval [CI] 4.0–34.1) in the LD+ASCT group compared with 21.2 months (95% CI 11.0–22.9) in the LD group. Overall, 18 patients have PD (10 patients in the LD+ASCT arm and 8 patients in LD arm), and 8 patients have died (4 patents in the LD+ASCT arm and 4 patients in the LD arm). Median PFS for LD+ASCT versus LD was 17.0 months (95% CI 15.5–not estimable) versus 25.2 months (95% CI 9.0–not estimable; p=0.94). Median OS for LD+ASCT versus LD was 57.6 months (95% CI 48.0–not estimable) versus not reached (p=0.94). Two patients in the LD alone arm developed a secondary malignancy, including 1 patient with myelodysplastic syndrome (MDS) 13 months after the start of therapy.

This interim analysis of an ongoing randomized clinical study comparing lenalidomide plus low-dose dexamethasone induction with and without upfront ASCT in patients with newly diagnosed MM suggests that addition of ASCT resulted in a trend towards improved ORR. This did not result in a significant difference in terms of PFS or OS between the two treatment arms. In contrast there was a trend of better DOR in the LD alone arm. The data show that LD alone can achieve similar results as LD+ASCT, however careful interpretation is required due to the low patient number and relatively short follow-up. The incidence of secondary malignancy was low, including the development of 1 MDS.