The purpose of this study is to determine the clinical benefit and characterize the safety profile of tabelecleucel for the treatment of Epstein-Barr virus-associated post-transplant lymphoproliferative disease (EBV+ PTLD) in the setting of (1) solid organ transplant (SOT) after failure of rituximab (SOT-R) and rituximab plus chemotherapy (SOT-R+C) or (2) allogeneic hematopoietic cell transplant (HCT) after failure of rituximab.