Potential Biomarkers of Therapeutic Response to ECP in Solid Organ Transplantation

One of the major hurdles in solid organ transplantation is graft rejection, which must be prevented with lifelong general immunosuppression. However, modern maintenance immunosuppression is accompanied by serious side effects, such as an increased risk of infection and malignancies. The search for alternative therapies specifically controlling allogeneic responses is fueling renewed interest in extracorporeal photopheresis (ECP). Despite guideline indications for ECP in cardiothoracic transplantation, potential applications in liver and kidney transplantation have not been adequately investigated. Presently, limited understanding of the pharmacodynamic effects of ECP and lack of consensus biomarkers are hindering the development of standardized multiparametric assays to assess patient responses. This review explores current knowledge about immune responses after ECP in transplant recipients and collates a set of biomarkers associated with favorable treatment responses.