A small step yet one giant leap for cGVHD biomarkers

In this issue ofBlood, Ng et al 1 have delineated 3 biologic subtypes of pediatric chronic graft-versus-host disease (cGVHD) with distinct immune and metabolomic signatures, outlining a cautious path toward biomarkerguided stratification and individualized therapy.cGVHD remains a major complication after allogeneic hematopoietic cell transplantation (HCT), contributing substantially to morbidity and nonrelapse mortality.The pathogenesis of cGVHD is complex and heterogeneous, and includes dysregulated innate and adaptive immunity and aberrant T-and B-cell interactions leading to end-organ damage with fibrosis, 2 complicating efforts to discover and validate mechanistically informative biomarkers to differentiate cases based on their underlying mechanisms.Despite extensive efforts to develop biomarkers for diagnosis, classification, treatment response, and prognosis of cGVHD, these endeavors have not yet succeeded. 3