Comparison of outcomes after human leukocyte antigen-matched and haploidentical hematopoietic stem-cell transplantation for multiple myeloma.

BACKGROUND: Allogeneic stem-cell transplantation (SCT) is a well-established immunotherapeutic strategy for multiple myeloma (MM) with a potent and often sustained graft-vs.-myeloma effect. This multicenter investigation aimed to analyze the complications and survival of haploidentical SCT in patients with MM, and compare the main outcomes with matched-related donors (MRDs). METHODS: Haploidentical and MRD SCT was identified from a cohort of 97 patients with MM who received a myeloablative transplantation in 13 hospitals from May 2001 to December 2017. A matched-pair analysis was designed. For each haplo recipient, the recipients were randomly selected from the MRD group and were matched according to the following criteria: year of the hematopoietic SCT (±2 years), disease status at transplantation, and the length of follow-up. RESULTS: Seventy cases received MRD and 27 received haploidentical transplantation. The two groups showed no significant differences regarding age, gender, cytogenetic risk, and diagnostic stage. The cumulative incidences of non-relapse mortality (NRM) at 1 and 3 years based on donor type were 20.5% (95% confidence interval [CI], 10.90-30.10%) and 24.2% (95% CI, 13.81-34.59%) for the MRD group and 16.80% (95% CI, 1.71-31.89%) and 28.70% (95% CI, 8.71-48.69%) for the haplo group, respectively. Cumulative incidence of NRM did not differ significantly between the two groups (χ = 0.031, P = 0.861). The cumulative incidences of progression-free survival (PFS) and 1 year and 3 years by type of donors were 59.8% (95% CI, 48.24-71.36%) and 45.4% (95% CI, 33.44-57.36%), and 65.6% (95% CI, 47.18-84.02%) and 26.8% (95% CI, 7.59-46. 01%) for MRD and haploidentical donor, respectively. Cumulative incidence of PFS did not differ significantly between the two groups (χ = 0.182, P = 0.670). In multivariate analyses, no statistically significant differences were observed between haploidentical and MRD for relapse, NRM, PFS, and overall survival. There were no statistically differences on main outcomes after haploidentical and MRD. CONCLUSION: Haploidentical SCT could be performed safely and feasibly for patients with MM in need.