Lenalidomide-Based Maintenance after Autologous Hematopoietic Stem Cell Transplantation for Patients with High-Risk Multiple Myeloma

Maintenance therapy with single-agent lenalidomide (Len) after autologous hematopoietic stem cell transplantation (autoHCT) for multiple myeloma (MM) is associated with improved progression-free survival (PFS). However, MM patients with high-risk chromosomal abnormalities (HRMMs) may need a more intense regimen. We hypothesized that adding another antimyeloma drug to Len maintenance would lead to improved outcomes. We conducted this retrospective single-center chart review analysis of adult HRMM patients who underwent autoHCT between 2008 and 2018, followed by Len-based maintenance therapy. High-risk cytogenetics were defined as del(17p), t(4;14), t(14;16), 1q21 gain or amplification by fluorescence in situ hybridization. We divided patients into those who received either single-agent Len maintenance (Len-only) or Len-based combinations (Len-combo). We compared nonrelapse mortality, day 100 and best post-transplantation responses, minimal residual disease status, PFS, and overall survival (OS) between the 2 groups. We also performed sensitivity analyses using inverse probability weights to correct for potential bias owing to nonrandomization of the 2 groups. A total of 231 patients with HRMM were included in our analysis, with a median age of 62.4 years (range, 33.5 to 79.9 years), and 55% were male. There were 153 patients in the Len-only group and 78 in the Len-combo group. Len-combo regimens were either doublets (Len with dexamethasone [dex] [n = 10], elotuzumab [n = 28], or ixazomib [n = 14]) or triplets (Len with bortezomib/dex [n = 10], ixazomib/dex [n = 10], or carfilzomib/dex [n = 6]). More patients in the Len-combo group had ≥2 high-risk cytogenetic abnormalities compared with the Len-only group (32% versus 12%: P < .001). The median duration of follow-up was 40.7 months in the Len-only group and 37.0 months in the Len-combo group. For all patients, the median PFS was 25.5 months, and the median OS was 82.6 months. There was no significant between-group difference in PFS (hazard ratio [HR] 1.01; 95% confidence interval [CI], .71-1.44; P = .94) or OS (HR, .84; 95% CI, .49 to 1.43; P = .52). However, for patients with high-risk cytogenetic abnormalities other than 1q+, there was a trend toward better PFS in the Len-combo group (HR, .59; 95% CI, .32 to 1.09; P = .09), but no difference in OS (HR, .79; 95% CI, .37 to 1.65; P = .53). In this single-center retrospective analysis, the use of Len-based combinations for post-transplantation maintenance was not associated with improved outcomes in HRMM patients; however, there was a trend toward improved PFS in patients with high-risk abnormalities other than 1q+.