Management of Post-Transplant Steroid-Resistant Graft-versus-Host Disease with Ruxolitinib in a High-Risk NUP98-NSD1–Positive Acute Myeloid Leukaemia: A Case Report

Abstract

Background: Steroid-resistant chronic graft-versus-host disease (cGVHD) after allogeneic haematopoietic stem cell transplantation is difficult to manage in young children because evidence on age-specific ruxolitinib dosing and safety remains limited. Case Presentation: A 7-year-old girl with high-risk acute myeloid leukaemia harbouring NUP98-NSD1 and FLT3-ITD underwent haploidentical peripheral blood stem cell transplantation after achieving complete remission with undetectable measurable residual disease. Seven months after transplantation, she developed biopsy-confirmed, moderate cGVHD involving the skin and oral mucosa. Symptoms progressed despite prednisolone and tacrolimus, with recurrent flares during corticosteroid tapering. Ruxolitinib was initiated at 5 mg twice daily, guided by age-stratified paediatric dosing, together with low-dose prednisolone. Voriconazole was discontinued before treatment because of the anticipated pharmacokinetic interaction. Skin and oral manifestations improved markedly within three weeks, and prednisolone was withdrawn within two months. Ruxolitinib was subsequently reduced, tapered, and discontinued without recurrence of cGVHD. Haematological, renal, and hepatic parameters remained clinically stable, and no significant cytopenias, hepatotoxicity, opportunistic infections, or viral reactivation occurred. Bone marrow assessments confirmed continuing morphological remission, undetectable measurable residual disease, undetectable NUP98-NSD1 and FLT3-ITD transcripts, and 100% donor chimerism. Conclusion: This case demonstrates a favourable clinical response to carefully monitored, age-adjusted ruxolitinib in a child younger than 12 years with steroid-resistant cGVHD, while emphasising the need for continued long-term surveillance.