A recent study determined relative contributions of human leukocyte antigen (HLA)-matching and donor relatedness to graft-related outcomes for patients with beta thalassemia major. Results were presented at the 60th American Society of Hematology (ASH) Annual Meeting in San Diego, California.

A total of 1110 patients received transplanted grafts from an HLA-matched relative (61%), an HLA-matched unrelated donor (23%), an HLA-mismatched unrelated donor (9%), or an HLA-mismatched relative (7%). At transplantation, the median patient age was 6 years (range: < 1-25), and the study had a median follow-up time of 48 months (range: 3-193).

Compared with transplants from HLA-matched siblings, grafts from mismatched relatives showed an overall mortality hazard ratio (HR) of 3.03 (P <.001) and a treatment failure HR of 2.75 (P <.001). HLA-matched unrelated donor grafts showed an overall mortality HR of 1.13 (P =.67) and a treatment failure HR of 1.25 (P =.39). HLA-mismatched unrelated donor grafts showed an overall mortality HR of 1.56 (P =.16) and a treatment failure HR of 1.60 (P =.08).

Graft-versus-host-disease risks were significantly higher with grafts from all other donor categories than with those from HLA-matched siblings.

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At 5 years after transplant, the rate of graft failure was highest for patients aged 16 to 25 years (23%) and was lowest for patients 6 years of age and younger (8%; P =.01). Five-year overall and disease-free survival probabilities were negatively associated with patient age.

The authors concluded that for patients with beta thalassemia major, transplant grafts should come from HLA-matched siblings or HLA-matched unrelated donors, with mismatched related donor grafts carrying a higher risk of treatment failure and mortality, and with patients aged 6 years and younger showing better outcomes.

Reference

1. Li C, Mathews V, George B, et al. Related and unrelated donor transplantation for β thalassemia major: results of an international survey. Oral presentation at: 60th ASH Annual Meeting and Exposition; December 1-4, 2018; San Diego, CA. Abstract 308.