Outcomes of Autologous Stem Cell Transplantation in Patients with Ultra-High-Risk Multiple Myeloma

Multiple myeloma (MM) patients with high-risk cytogenetic abnormalities have inferior survival outcomes and are underrepresented in clinical trials. There is scarce data on MM patients with more than one high-risk cytogenetic aberration (ie, ultra- high-risk MM). This study was conducted to evaluate outcomes of newly diagnosed MM patients with ultra-high-risk MM who underwent autologous hematopoietic stem cell transplantation (autoHCT). We conducted a retrospective single-center chart review analysis of adult patients with ultra-high-risk MM who underwent autoHCT between 2008 and 2018 at MD Anderson Cancer Center. High-risk cytogenetics were defined as del(17p), t(4;14), t(14;16), or 1q21 gain or amplification (1q+) by fluorescence in situ hybridization. Primary endpoints were progression-free survival (PFS) and overall survival (OS). Seventy-nine patients with two or more high-risk cytogenetic abnormalities were included in our analysis. The median age of 61 years (range, 33.5 to 76.5 years), and 57% were female. Sixty-seven patients had two high-risk cytogenetic abnormalities, and 12 patients had three high-risk cytogenetic abnormalities. The most common combinations of high-risk abnormalities were [1q+, t(4:14)] (n = 25; 32%) and [1q+, del17p] (n = 21; 27%). The majority of patients received either bortezomib, lenalidomide, and dexamethasone (48%) or carfilzomib, lenalidomide, and dexamethasone (16%) as induction therapy. Prior to autoHCT, 52 patients (66%) achieved a very good partial response or better (≥VGPR), whereas 23 patients (29%) achieved minimal residual disease (MRD)-negative ≥VGPR. Fifty-six patients (71%) received post-transplantation maintenance therapy. Thirty-six patients (46%) achieved MRD-negative ≥VGPR at day +100 after autoHCT, and 40 patients (51%) did so at best post-transplantation response. With a median follow-up in surviving patients of 38.3 months (range, 11.9 to 104.8 months), the median PFS and OS in the entire cohort were 22.9 months and 71.5 months, respectively. For the subset of patients with three HR abnormalities, the median PFS was 15.6 months and median OS was 28.0 months. In multivariate analysis, achieving MRD-negative ≥VGPR prior to autoHCT was associated with improved PFS (hazard ratio [HR], .42; P = .045), whereas male sex (HR, .15; P = .009) and achieving MRD-negative ≥VGPR post-autoHCT (HR, .27; P = .026) were associated with improved OS. In conclusion, patients with ultra-high-risk MM have a median PFS of <24 months with the current standard of care that includes consolidation with autoHCT. These patients may benefit from earlier use of newer treatment modalities, such as chimeric antigen receptor T cell therapy and bispecific antibodies.