Historical Perspective of Allogeneic Hematopoietic Stem Cell Transplantation for Multiple Myeloma

Background: Advances in novel therapies have improved outcomes for multiple myeloma (MM) patients and the use of allo-SCT has decreased. Current guidelines no longer support allo-SCT as consolidation therapy for newly diagnosed MM, even in high-risk cases. Summary: Allo-SCT is now typically considered only within clinical trials for young, high-risk patients with relapsed or refractory MM (RRMM). It has not proven favorable despite its historical use. CAR T-cell therapy and bispecific antibodies have shown promise in treating triple- and penta-exposed/refractory MM, yet relapse remains common with poor survival rates. The efficacy of allo-SCT following BCMA-directed therapy and other new T-cell-directed therapies is unclear. Allo-SCT might be a viable option for eligible patients who relapse after these therapies, or where such options are unavailable. Advancements in reduced-intensity conditioning regimens have led to lower toxicity and transplant-related (TR) morbidity, lower graft-versus-host disease (GvHD), and TR mortality. Expanded use of alternative donors, like haploidentical donors, has yielded comparable outcomes. Better post-transplant GvHD regimens and maintenance strategies to prevent relapse have been developed. Key messages: This review analyzes available literature to better understand the safety, efficacy, and current role of allo-SCT in managing MM. Newer regimens are needed as routine use of allo-SCT cannot be recommended.