Role of BK Virus CTLs in the Treatment of BK Virus–Associated Nephropathy in Kidney-Transplant and Hematopoietic Cell Transplant Recipients

Background: BK virus infection is a marker of poor immune recovery, especially after kidney or allogeneic cell transplantation. Because of the challenges associated with BK virus infection and the lack of effective treatments, there is a growing interest in novel approaches, such as adoptive cellular therapy, that aim to restore antiviral immunity and promote viral clearance. Methods: Our clinical trial assessed the feasibility, safety, and efficacy of administering third-party, BK virus-specific cytotoxic T lymphocytes (CTLs) used to treat allogeneic HCT patients and kidney transplant patients with biopsy-proven BK-virus nephropathy. Comprehensive clinical assessments and correlative studies were performed. Results: The study included six patients after kidney-transplantation and five HCT recipients. Viremia declined in most evaluable patients by Day 45 after BKCTL infusion. No new instances of graft-versus-host disease, kidney-transplant rejection, graft failure, or infusion-related toxicities were attributed to the treatment. Antiviral activity (as assessed by interferon-γ secretion) did not differ between infused BKV-CTLs given to kidney-transplant versus allogeneic SCT recipients. Conclusion: In this study, we longitudinally tracked the in vivo persistence of adoptively transferred BKV-CTLs and demonstrated their sustained functional activity. This therapy could be promising in KT and SCT patients with recent-onset BK-virus viremia. (Figure presented.).