Predictors of inferior clinical outcome in patients with standard-risk multiple myeloma

Introduction: Outcome of patients with standard-risk (SR) multiple myeloma (MM) has improved; however, subsets of patients do worse than expected. We sought to identify the factors associated with inferior outcome. Methods: We evaluated 51 patients with SR MM that received upfront autologous hematopoietic stem cell transplantation (auto-HCT) after induction and had a progression-free survival (PFS) of ≤18 months. Results: The median age of patients was 61 yr. Forty-one (80%) patients received induction with immunomodulatory drugs, proteosome inhibitors, or combination of both. The overall response rate (ORR) after auto-HCT was 96% (stringent complete response 23%, complete response 10%, very good partial response 22%, and partial response 39%). The median PFS was 7.8, and median overall survival (OS) was 56.3 months. On univariate analysis, concurrent light-chain amyloidosis (AL) was associated with inferior PFS [hematological response (HR); 2.51, 95% CI; 0.64–10.58, P = 0.03] and occurrence of soft tissue plasmacytoma was associated with a significantly shorter OS (HR: 3.05, 95% CI: 0.57–16.29, P = 0.02). Conclusion: Our analysis suggests that concurrent AL and soft tissue plasmacytoma were associated with shorter PFS and OS, respectively. Heterogeneity in clinical outcome of SR MM merits better tools for prognostication, such as gene expression profiling and minimal residual disease assessment to identify high-risk patients.