Allogeneic Stem Cell Transplantation in Relapsed/Refractory Multiple Myeloma Treatment: Is It Still Relevant?

Background: Despite offering an attractive option, the role of allogeneic stem cell transplantation (alloSCT) for treatment of multiple myeloma (MM) remains unclear. Methods: Recognizing the paucity of data in the Asian population, we retrospectively evaluated the outcomes of 24 patients (median age 52) undergoing alloSCT between April 2003 and November 2017. Results: The median time from diagnosis to alloSCT was 39.4 months. The majority of the patients (70.8%) underwent alloSCT followed by reduced intensity conditioning regimens after a median of five lines of therapy. Among 24 patients, 15 patients (62.5%) had a high-risk MM feature. The two-year relapse-free survival (RFS) and overall survival (OS) of the total patients were 29.2 ± 9.3% and 44.3 ± 10.3%, respectively. Patients who were treated with less chemotherapy lines (<5) before alloSCT had a prolonged RFS and OS. All patients (seven patients) who received a myeloablative conditioning regimen had high-risk features, but two out of seven patients showed long-term survival without lasting sequelae. Nine patients (37.5%) experienced non-relapse mortality (NRM) within one year after alloSCT (the one-year cumulative incidence of NRM was 38.3 ± 10.1%). Conclusion: AlloSCT can still be implemented as effective salvage option in the treatment of relapsed/refractory high-risk MM. The optimal timing of alloSCT remains to be determined.