Allo-HSCT: Unrelated, Haploidentical Donations May Yield Similar Outcomes

Stem cell transplantation
Both event-free and overall survival at 3 years were 96% for patients with transfusion-dependent thalassemia who underwent transplant.
No differences were noted in rates of grade 2 to 4 acute graft-versus-host disease, non-relapse mortality, or relapse risk.

Among patients older than 55 years undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT), relying on donations from a human leukocyte antigen (HLA)-matched unrelated donor (UD) or haploidentical donor (HaploD) may yield similar outcomes, according to research presented at the EHA 2022 Hybrid Congress.

The ideal scenario in allo-HSCT is the presence of a matched sibling donor, but such donors are not frequently available. It was, however, previously unclear whether using a UD or HaploD would yield superior outcomes among older patients.

The relative outcomes of these donations have important implications for the process of identifying potential donors. For this randomized phase 3 study (ClinicalTrials.gov Identifier: NCT02623309), researchers evaluated, in the case of unavailability of matched sibling donor, the relative safety and efficacy of allo-HSCT using HaploD or UD among patients older than 55 years. The study’s primary endpoint was chronic graft-vs-host disease-free relapse-free survival (GRFS).

Overall, 108 patients were enrolled and 106 patients were included in the analysis; 55 and 51 patients, respectively, were randomly assigned to the HaploD and UD groups. The median patient age was 65 years (range, 55-70), and 79% of patients had a myeloid malignancy.

The median follow-up was 27 months. In the analysis cohort, 73% of patients proceeded to transplant in both groups. The median time from randomization to transplantation was 76 days in the HaploD group vs 95 days in the UD group. Nine (16%) patients in the UD group and 11 (22%) patients in the HaploD group received an allo-HSCT donation from an individual in the HaploD and UD search groups, respectively.

Analysis of the intent-to-treat population showed that the 2-year GRFS rate was 29% in the HaploD group vs 37% in the UD group (P = .22); the 2-year progression-free survival (45% vs 49%; P = .56) and overall survival (50% vs 59%; P = .47) rates were also similar.

An overall analysis of 42 patients treated from a haploidentical donor and 35 patients from a UD confirmed that the primary endpoint was not significantly different (2-year GRFS, 40% vs 34%, respectively; P = .66).

No differences were noted in rates of grade 2 to 4 acute graft-versus-host disease, non-relapse mortality, or relapse risk.

Disclosures are not available for this presentation.

Reference

Harbi S, Boher J-M, Forcade E, et al. Randomized multicenter phase III study of haplo versus HLA-matched unrelated donor (UD) allogeneic hematopoietic stem cell transplantation (ALLO HSCT) for patients older than 55 years. Presented at EHA 2022; June 9-12, 2022. Abstract S236.

This article originally appeared on Hematology Advisor