Acute kidney injury during ruxolitinib therapy in pediatric patients with graft-versus-host disease: incidence, associated factors, and histopathological findings in a retrospective cohort study

Ruxolitinib is a cornerstone treatment for steroid-refractory graft-versus-host disease (GVHD) following allogeneic hematopoietic stem cell transplantation (HSCT) in children, yet longitudinal data on kidney function during such therapy remain limited. We retrospectively analyzed 38 pediatric patients (0–18 years) receiving ruxolitinib for acute or chronic GVHD between January 2018 and December 2025, assessing kidney function at six timepoints from baseline to month 6. Mean serum creatinine rose from 0.34 ± 0.16 mg/dL at baseline to 0.50 ± 0.34 mg/dL at month 3 (p < 0.001) and remained mildly elevated at month 6 (0.48 ± 0.23 mg/dL; p < 0.001). Acute kidney injury (AKI) occurred in 7 patients (18.4%) at a median of 2.36 months after ruxolitinib initiation, with 4 (57.1%) progressing to acute kidney disease; biopsies excluded BK virus nephropathy. BK virus reactivation, BKV-related hemorrhagic cystitis, CMV reactivation, older age at transplantation, and higher baseline creatinine were significantly associated with AKI, whereas ruxolitinib dose was not. Post-transplant AKI in this setting appears multifactorial; controlled studies including a ruxolitinib-unexposed comparator group are needed to clarify the specific contribution of the drug.