Immune reconstitution rates and survival outcomes in patients with myeloid malignancies receiving matched unrelated donor allo-HCT

This retrospective bi-centric study included 252 patients with myeloid malignancies undergoing matched unrelated donor allo-HCT. The primary exposure was GVHD-prophylaxis using either anti-thymocyte globulin or post-transplant cyclophosphamide. Follow-up occurred at day +365 and month +18. The main results focused on immune reconstitution, overall survival, transplant-related mortality, and therapy-requiring acute or chronic GVHD. Safety and tolerability data were not reported. Funding or conflicts of interest were not reported.

By day +365, 16.7% of patients achieved immune reconstitution. Superior overall survival was associated with immune reconstitution, with a hazard ratio of 0.39 (95% CI 0.17–0.90; p=0.026). Lower transplant-related mortality was also associated with immune reconstitution, with a hazard ratio of 0.08 (95% CI 0.01–0.63; p=0.017). Delayed immune reconstitution was associated with therapy-requiring acute or chronic GVHD, with a hazard ratio of 0.31 (95% CI 0.20–0.48; p not reported).

Regarding factors influencing the probability of immune reconstitution by month +18, younger donor age and PTCy were associated with higher probability. The sHR for donor age was 0.97 (95% CI 0.94–1.00; p=0.037), and the sHR for PTCy was 0.49 (95% CI 0.27–0.84; p=0.01). The association between PTCy and immune reconstitution was attenuated after adjusting for therapy-requiring acute or chronic GVHD. Effects on immune reconstitution in matched unrelated donor allo-HCT remain incompletely defined.