Late-onset Acute and Chronic Graft-Versus-Host Disease in Children: Clinical features and Response to Therapy.

While acute graft-versus-host disease (aGVHD) and chronic GVHD (cGVHD) are known causes of morbidity and mortality after allogeneic hematopoietic cell transplantation (HCT), the syndrome of late acute GVHD is less well understood, particularly in children. We aimed to characterize the clinical features and response to therapy of late aGVHD and cGVHD by retrospectively reviewing 573 consecutive patients aged <18 years old who underwent their first allogeneic HCT at the University of Minnesota. We included patients with de novo late aGVHD (i.e., the first occurrence of aGVHD at >day 100 after HCT) and cGVHD. We retrospectively scored cGVHD cases based on the 2014 guidelines by the National Institute of Health. At 3 years, 9 (2%) patients developed late aGVHD, 16 (3%) overlap cGVHD, and 7 (1%) classic cGVHD. No cases with joint or genital cGVHD were observed. The overall response to therapy at 6 months was 78% (95%CI: 40-97) after late aGVHD and 43% (95%CI: 23-66%) after cGVHD. Higher non-relapse mortality from day +100 was shown in those with cGVHD but not with late aGVHD as compared to those without neither of the types of GVHD (hazard ratio [95% confidence interval], 3.6 [1.3-10.0] and 1.6 [0.2-11.7], respectively). In summary, we described variable organ involvement and treatment response between late aGVHD and cGVHD in a single-center pediatric cohort. Future research is required to investigate the risks and clinical features of late aGVHD and cGVHD in larger cohorts to better understand how to tailor even more effective GVHD preventive and therapeutic approaches in children.