BEAT-BK: An Adaptive, Randomized Controlled Trial to Treat Polyomavirus Infections (BKPyV) in Kidney and Kidney-pancreas Transplantation Recipients (BEAT-BK) Study Protocol

Background: BK polyomavirus (BKPyV) is a common opportunistic infection in kidney transplant recipients, typically reactivating in the context of immunosuppression. Although asymptomatic in immunocompetent individuals, reactivation in transplant recipients can cause BKPyV-associated nephropathy (BKPyVAN), a leading cause of graft dysfunction and loss. BKPyV viremia affects approximately 10%-15% of transplant recipients, and once BKPyVAN is established, the risk of graft failure can exceed 50%. The current standard of care involves immunosuppression reduction to restore virus-specific immunity, but this approach increases the risk of acute and chronic rejection. Intravenous immunoglobulin (IVIg), which contains antiviral and immunomodulatory antibodies, has been proposed as an adjunctive therapy, although evidence supporting its efficacy remains limited to small observational studies. Methods: The BEAT-BK trial is a multicenter, adaptive, randomized controlled trial comparing standard immunosuppression reduction with or without IVIg in kidney and simultaneous pancreas-kidney transplant recipients with BKPyV viremia or biopsy-confirmed BKPyVAN. The trial will enroll participants aged 2 y and older, randomizing them 1:1 to receive standard care alone or in combination with a total IVIg dose of 2 g/kg for 8 wk. An adaptive Bayesian design will permit interim analyses with the potential for early trial success or futility. Results: The primary endpoint is a composite ordinal outcome at 12 wk, incorporating death, graft loss, estimated glomerular filtration rate decline, acute rejection, viral load, and degree of immunosuppression reduction. Secondary outcomes include viral clearance, development of BKPyVAN and donor-specific antibodies, infections, malignancy, quality of life, and cost-effectiveness. Conclusions: This trial will provide the first high-quality evidence on the role of IVIg in BKPyV management and inform clinical decision-making in posttransplant care.