Distinct biological subtypes of chronic GVHD after pediatric hematopoietic cell transplantation

Chronic graft-versus-host-disease (cGVHD) is the primary nonrelapse limitation to a successful hematopoietic cell transplantation and is largely treated as a single biological entity. We hypothesized that there exist different biological subtypes of cGVHD. Using the Applied Biomarkers of Late Effects of Childhood Cancer (ABLE) network database, which is derived from the largest pediatric cGVHD cohort worldwide, we applied clustering analysis to subtype patients with cGVHD from the ABLE1.0 and 2.0 studies (51 patients with cGVHD and 158 with non-cGVHD). We found 3 distinct cGVHD subtypes: cGVHD-1 was characterized by an effector memory T-cell, cytotoxic natural killer cell, and early precursor B-cell predominant pattern; cGVHD-2 was phosphatidylcholine, cytokine, and plasma cell predominant; and cGVHD-3 had more naïve CD4⁺T cells and naïve regulatory T cells, had later onset, and was the only subtype with measurable T-cell receptor excision circles. We partially replicated these subtypes using metabolomic data from a separate pediatric cohort of the Children’s Oncology Group trial ASCT0031 (33 patients with cGVHD and 39 with non-cGVHD). Furthermore, cGVHD-1 was associated with serotherapy (predominantly antithymocyte globulin) exposure, and cGVHD-3 was associated with receiving peripheral blood stem cells from donors, total body irradiation, and no previous acute GVHD. cGVHD-2 was associated with liver involvement and cGVHD-2 and -3 with de novo cGVHD. Overall, none of the subtypes were closely associated with organ involvement. Contrasting each subtype against patients with non-cGVHD, the 3 subtypes shared common markers, all of which were used in our previous cGVHD diagnostic classifier. These findings suggest the presence of distinct biological subtypes of cGVHD that may help guide therapeutic strategies.