This open-label, single-arm clinical trial will assess the safety and efficacy of BK virus-specific CTLs isolated from whole blood or leukapheresis products. The BK virus -specific CTLs will be generated automatically by the CliniMACS Prodigy using the CliniMACS Cytokine Capture System (IFNgamma) after incubation with MACS GMP PepTivator Peptide Pools of BKV VP1 and BKV LT.

