Successful treatment of severe, refractory polyomavirus disease with partially HLA-matched donor-derived BKPyV-specific T cells in a pediatric kidney recipient.

BK polyomavirus-associated nephropathy is a significant therapeutic challenge in kidney transplant recipients, often leading to allograft dysfunction. We report on a 12-year-old male kidney transplant recipient with severe, biopsy-proven BK polyomavirus-associated nephropathy and concurrent JC polyomavirus (JCPyV)-associated neurological symptoms. Due to failure of standard therapy, adoptive transfer of partially HLA-matched, BK polyomavirus-specific T cells from the kidney donor was administered as rescue therapy. The intervention induced a rapid decline in both BK polyomavirus (BKPyV) and JCPyV viral loads. This virological response was accompanied by the resolution of neurological symptoms and stabilization of allograft function. This case indicates that donor-derived BK polyomavirus-specific T cells represent a viable therapeutic modality for severe, refractory polyomavirus disease.