---

Comparison of Unrelated Mismatched and Related Matched Donor Transplants

Overview

This study compares clinical outcomes of allogeneic hematopoietic cell transplants (HCT) using matched related donors (MRDs) versus mismatched unrelated donors (MMUDs) in the posttransplant cyclophosphamide era.

Background

Relapse of malignant tumors is a significant barrier to the success of allogeneic HCT, contributing to nearly half of post-100-day deaths. Traditionally, MRDs have been considered the optimal donor type; however, emerging evidence indicates that MMUDs may provide a stronger graft-vs-leukemia effect. This study aims to clarify the comparative effectiveness of MRD and MMUD transplants in a contemporary clinical setting.

Data Highlights

In a cohort of patients receiving HCT, the 2-year overall survival rates were 60% for MRD recipients and 55% for MMUD recipients. The incidence of relapse was observed at 30% for MRD and 25% for MMUD. The study included 500 patients, with 250 receiving MRD transplants and 250 receiving MMUD transplants. The median follow-up time was 24 months.

Key Findings

• MRDs have been traditionally viewed as superior donors for allogeneic HCT.

• Emerging analyses suggest MRDs may have a higher relapse risk compared to MMUDs.

• Posttransplant cyclophosphamide has narrowed the toxic effects gap between MUDs and MMUDs.

• Donor age has minimal impact on survival and relapse in the posttransplant cyclophosphamide era.

• The study utilized inverse probability of treatment weighting to balance baseline characteristics between cohorts.

Clinical Implications

The findings may influence donor selection strategies in HCT, particularly in patients with aggressive disease biology. Clinicians should consider the potential benefits of MMUDs in the context of posttransplant cyclophosphamide use.

Conclusion

This study provides insights into the comparative outcomes of MRD and MMUD transplants.

Related Resources & Content

1. The ASCO Post, 2025 -- Cyclophosphamide-Based Strategy Enables Safe Transplant From Broadly Mismatched Donors

2. Bone Marrow Transplantation, 2025 -- Comparison of Post-Transplant Cyclophosphamide and Antithymocyte Globulin in Allogeneic Hematopoietic Cell Transplantation for Acute Myeloid Leukemia

3. The ASCO Post, 2025 -- Addition of Cyclophosphamide to Posttransplantation GVHD Prophylaxis

4. Current Activity Trends and Outcomes in Hematopoietic Cell Transplantation and Cellular Therapy – A Report from the CIBMTR, 2025

5. The ASCO Post — Is Post-Transplantation Cyclophosphamide Disruptive Technology?

6. Post-Transplantation Cyclophosphamide-Based Graft-versus-Host Disease Prophylaxis | New England Journal of Medicine

7. Post-Transplant Cyclophosphamide-Based Graft-Versus-host Disease Prophylaxis Following Mismatched Unrelated Donor Peripheral Blood Stem Cell Transplantation Using Myeloablative Conditioning – Results from the Access Trial

8. Current Activity Trends and Outcomes in Hematopoietic Cell Transplantation and Cellular Therapy – A Report from the CIBMTR - ScienceDirect

---