Allogeneic Hematopoietic Stem Cell Transplantation in Relapsed Refractory Multiple Myeloma.

Objectives: Allo-Hematopoietic Stem Cell Transplantation (HSCT) offers a curative option for relapsed and refractory multiple myeloma in younger aged and fit patients with high-risk cytogenetic properties.

Material and methods: This study retrospectively enrolled the medical data of 30 patients who had undergone allogeneic stem cell transplantation at the Gazi University Adult Stem Cell Transplant Unit between 2005 and 2020.

Results: Before allo-SCT, 6 (20.0%) patients were in complete remission; 8 (26.6%) had a partial response; 14 (46.6%) had progressive disease, and 2 (6.6%) had stable disease. Overall survival (OS) at 1, 2, 3, and 5 years post-transplant were 45%, 36.3%, 31.7%, and 22.7%, respectively; transplant-related mortality (TRM) was 25.0% at 100 days. While the 5-year OS was 11.7% in the group with less than PR according to the pre-transplant disease status, it was found to be statistically significant as 45.8% in the group with CR or PR (P = 0.001). TRM was significantly higher in patients with less than PR compared has CR or PR at pre-transplantation (100% vs. 43.7% P = 0.01). Like these findings, PFS was shorter in patients with less than PR compared has CR or PR at pre-transplantation (6.2 vs. 77.1 months, P = 0.01).

Conclusions: We found longer OS and PFS in patients with a complete response before allo-SCT. This shows that the depth of response before allogeneic stem cell transplantation is effective on 100-day TRM in multiple myeloma patients. Allo-HSCT may be a therapeutic option in MM patients who relapse/refractory after auto-SCT, particularly after achieving the least partial response.