Relapse after Allogeneic Hematopoietic Cell Transplantation for Multiple Myeloma: Survival Outcomes and Factors Influencing Them

Many patients with multiple myeloma (MM) eventually relapse even after allogeneic hematopoietic cell transplantation (alloHCT) for curative intent. Over the past decade, outcomes for patients with MM have improved significantly with the availability of new therapies, including next-generation proteasome inhibitors, immunomodulatory agents, and, more recently, monoclonal antibodies. Although several published studies have evaluated the outcomes of alloHCT for MM, the data on survival outcomes in patients with MM experiencing disease relapse following alloHCT are limited. In addition, the predictors for postrelapse survival in these patients are not known. In this study, we examined the outcomes of a single-center cohort of 60 patients with MM who experienced relapse or progression after alloHCT. In addition, we evaluated the use of salvage regimens for treatment of relapsed MM and analyzed the predictors for improved postrelapse survival. After a median follow-up of 2.2 years from the time of relapse, the median duration of postrelapse survival was 1.8 years (95% confidence interval [CI], 1.2 to 5.0 years). Patients received a median of 3 lines of therapy (range, 0 to 10) for treatment of MM beyond the post-alloHCT relapse/progression. Multivariate analysis identified cytogenetic risk (standard risk versus high risk; hazard ratio [HR], .34; P = .01), time to relapse after alloHCT (>12 months versus ≤12 months: HR, .41; P = .04), and occurrence of acute graft-versus-host disease (GVHD) before relapse (GVHD versus no GVHD: HR, 2.89; P = .01) significantly affected postrelapse survival. These data illustrate that long-term myeloma control and survival is attainable in those relapsing/progressing after alloHCT and suggest that the synergism between novel therapies and the allogeneic immune platform is the key to improved survival in this high-risk patient population.