Post-transplant lymphoproliferative disorder: Update on treatment and novel therapies.

Post-transplant lymphoproliferative disorder (PTLD) is rare and heterogeneous lymphoid proliferations that occur as a result of immunosuppression following solid organ transplant (SOT) and haematopoietic stem cell transplant (HSCT) with the majority being driven by EBV. Although some histologies are similar to lymphoid neoplasms seen in immunocompetent patients, treatment of PTLD may be different due to difference in pathobiology and higher risk of treatment complications. The most common treatment approach in SOT PTLD after failing immunosuppression reduction (RIS) takes into consideration a risk-stratified sequential algorithm with rituximab +/- chemotherapy based on phase 2 studies. In HSCT PTLD, RIS alone and chemotherapy are usually ineffective making rituximab +/- RIS as the gold standard of frontline treatment. In this review, we give an update on the treatment of PTLD beyond RIS. We highlight the most recent studies that attempted to incorporate more aggressive chemotherapy regimens and novel treatments into the traditional risk-stratified sequential approach. We also discuss the role of EBV-cytotoxic T lymphocytes in treatment of EBV-driven PTLD. Other novel agents with potential role in PTLD will be discussed in addition to the challenges that could arise with chimeric antigen receptor T-cell therapy and immune checkpoint inhibitors in this population.