Peripheral Blood Stem Cell Transplantation From Haploidentical and Unrelated Versus Related Donors for Acute Leukemia in Children, Adolescents and Young Adults (Caya): A Competing Risk Analysis Publisher



Rostami T¹ ; Rostami MR² ; Kiumarsi A¹ ; Kasaeian A³ ; Alijani N⁴ ; Fumani HK² ; Rad S² ; Babakhani D² ; Bahri T² ; Vaezi M² ; Barkhordar M² ; Mirhosseini SA² ; Mousavi SA² Show Affiliations
Source: Cellular Therapy and Transplantation Published:2022

Abstract

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only potentially curative treatment for acute leukemia. Various parameters have significant impact on the final results of HSCT, such as donor type, stem cell source, and the applied conditioning regimen. In the absence of HLA-matched related or unrelated donors, haploidentical donors present a possible alternative for the patients with indications for HSCT. The present single-center study compared the outcomes of HSCT from different donor types using a radiation-free MAC regimen. We compared the results of unmanipulated peripheral blood stem cell transplantation (PBSCT) from matched, or mismatched related, and unrelated donors with those from haploidentical donors in the children, adolescents and young adults (CAYA) treated for acute leukemia. Patients and methods In this retrospective study performed since 2014 to 2021, we have evaluated the clinical outcomes among CAYA patients with acute leukemia who underwent peripheral blood T cell-replete HSCT from haploidentical donors versus unrelated donors (including 10/10 or 9/10 HLAmatched), and versus related donors (including 10/10 or 9/10 HLA-matched). The myeloablative conditioning for HSCT was performed as irradiation-free regimen including busulfan and cyclophosphamide. GvHD prophylaxis was based on administration of cyclosporine A in all the patients, accomplished by rabbit anti-human thymocyte globulin in HSCT from unrelated and haploidentical donors, and post-transplant cyclophosphamide in cases of haploidentical donors. For statistical evaluation, an adjusted multivariable proportional hazard Cox and competing risk analyses were used. Results Median follow-up time period was 28.7 months (95% CI: 21.9-34.9). Three-year overall survival rate (OS) and GvHD-free/relapse-free survival (GFRFS) rate were 68.81% (95% CI: 60.08%-76.01%) and 44.19% (95% CI: 35.52%-52.49%), respectively. The patients who underwent HSCT from unrelated HLA-matched donors had the lowest OS and GFRFS compared to other donor types. The 3-year non-relapse mortality (NRM) in all patients was 7.84% (95% CI 4.36-12.62). Adjusted multivariable modeling of OS showed that the hazard of death in patients who had undergone HSCT from an unrelated donor, was 3.6 times more than for the patients who underwent HSCT from their haploidentical donors (P=0.05). Likewise, the hazard of NRM after HSCT from unrelated donors was 6 times more than with haploidentical donors (P=0.002). However, the relapse incidence was not significantly different between the two mentioned groups. Conclusions In this study, HSCT from haploidentical donors was associated with superior survival rates compared to HSCT from unrelated HLA-matched donors. Hence, haploidentical transplantation with peripheral blood stem cells could be a practical and valuable clinical option that offers a reasonable opportunity for the disease control in CAYA patients with acute leukemia requiring HSCT and lacking matched available donors. © 2022, Universitatsklinikum Hamburg - Eppendorf. All rights reserved.