https://orcid.org/0000-0002-2756-7301
Key Points
Older age, donor type, and history of pre-HCT serious infection impact overall and event free survival following HCT for WAS.
Busulfan-based conditioning regimens were associated with higher platelet counts post-HCT.
Wiskott-Aldrich syndrome (WAS), an X-linked disorder characterized by immunodeficiency, thrombocytopenia, autoimmunity, and malignancy, can be effectively treated with allogeneic hematopoietic cell transplantation (HCT). Older age at HCT and mismatched donors are known to impact overall survival (OS). The influence of specific clinical manifestations or WAS variant class on OS and factors associated with event-free survival (EFS) remain incompletely defined. We analyzed outcomes of 308 patients with WAS who underwent HCT at 37 institutions of the Primary Immune Deficiency Treatment Consortium (PIDTC) from 1990-2018. With a median follow-up of 5.3 years, the 5-year OS and EFS were 87.2% and 79.7%, respectively. Age ≥5 years, donor type, and a pre-HCT history of severe infection had a negative impact on OS and EFS, whereas pre-HCT autoimmunity had no impact. Reduced intensity regimens were associated with lower T cell and myeloid donor chimerism, particularly when non-busulfan-based regimens were used. Low myeloid donor chimerism was associated with lower platelet counts. Mixed chimerism was not consistently associated with post-HCT autoimmunity. Patients with class I (exon 1-2 missense and intron 5 hotspot variants) and class II variants (all others) had similar pre-HCT clinical symptom severity and no difference in OS, EFS or platelet recovery post-HCT. In conclusion, our study showed excellent long-term OS and EFS following HCT for WAS, highlighting the importance of early HCT, before the development of severe infections. We confirmed that HCT using busulfan-based conditioning was associated with improved donor chimerism and platelet recovery. This study was registered at www.clinicaltrials.gov as #NCT02064933.
