Graft-versus-host disease (GVHD) is a major complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT), significantly affecting survival and quality of life. Acute GVHD (aGVHD) typically occurs within 100 days post-transplant, commonly involving skin, gastrointestinal tract, and liver. Chronic GVHD (cGVHD) can appear months to years later.
Despite prophylaxis with calcineurin inhibitors (e.g., cyclosporine or tacrolimus), methotrexate, mycophenolate mofetil, and post-transplant cyclophosphamide (PTCy), patients receiving haploidentical transplantation from parous female donors remain at high risk for moderate-to-severe aGVHD.
JAK1-dependent cytokine signaling (IL-6, IFN-γ) is central to GVHD pathogenesis. Selective JAK1 inhibition may attenuate T cell-mediated inflammation while preserving hematopoiesis. Ivarmacitinib (SHR0302) is a highly selective oral JAK1 inhibitor, showing favorable safety and preliminary efficacy in autoimmune and GVHD settings, making it a candidate for early GVHD prophylaxis.