MM-269: Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Multiple Myeloma

Abstract

Introduction: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is not standard of care in patients with multiple myeloma (MM), but it is a potential treatment option and associated with a high risk of severe complications. Aim: To study the effectiveness of allo-HSCT for young patients with MM. Materials and methods: From 2013 to 2018, eight patients (6 male, 2 female) with MM, aged from 27 to 55 years (median 39 years), underwent allo-HSCT. All patients had adverse prognostic factors. During the induction therapy, the patients received from 2 to 4 lines of therapy. Before the auto-HSCT, a VGPR was achieved in 1 patient, a PR in 4 patients and a progression of disease in 3 patients. Seven patients underwent a tandem auto/allo-HSCT and one patient underwent an allo-HSCT. In all cases, an HLA-identical sibling donor was used. Reduced intensity conditioning regimen (fludarabine + busulfan + ATG) was performed in all patients. Immunosuppressive therapy included cyclophosphamide at +3 and +4 days. Results: The duration of agranulocytosis ranged from 12 to 26 days (median 19 days) after allo-HSCT. Acute GVHD was developed in 62.5% of cases, of which severe GVHD was noted in 25% of patients. 5 patients achieved CR; 3 patients had a VGPR 5 months after allo-HSCT. All patients achieved 100% donor molecular chimerism. When observed for 15 to 79 months (median 51 months) after allo-HSCT, CR was achieved in 62.5% of the patients. One patient died due to complications of severe GVHD. In 2 cases, 12 and 19 months after allo-HSCT, against the background of 100% molecular chimerism, myeloma progression was observed. 6-year PFS was 75%, 6-year OS was 89%, with a median observation of 51 months. Conclusion: Allo-HSCT can be considered as an effective treatment for young patients with high-risk MM. 6-year PFS and 6-year OS were 75% and 89%, respectively. A stringent CR was achieved in 62.5% of patients. Myeloma progression was noted in 2 cases against the background of 100% donor bone marrow chimerism. Severe acute GVHD was observed in 25% of cases. The high frequency of GVHD requires close monitoring and timely treatment. The transplant-related mortality rate was 12.5%.