Proliferation signal inhibitors in transplantation: questions at the cutting edge of everolimus therapy.

While advances in immunosuppressive therapy have allowed dramatic improvements in the control of acute allograft rejection, there is still a need to improve long-term graft and patient survival rates following renal and heart transplantation. Among the recognized threats to long-term organ survival are chronic allograft dysfunction in the form of chronic allograft nephropathy and cardiac allograft vasculopathy, with long-term patient morbidity and mortality further compromised by higher than normal rates of posttransplant cardiovascular disease, infection, and malignancy. A growing body of evidence finds that the selection and dosing of immunosuppressive therapies can have great influence on long-term transplantation outcomes. Early evidence suggests that the proliferation signal inhibitors (PSIs), everolimus and sirolimus, might offer effective immunosuppressive activity together with antiproliferative effects that may address some of the unmet needs in the long-term therapeutic management of the posttransplant patient. This review summarizes the emerging evidence for employing PSI-based immunosuppression to seek a balance between the goals of maximizing graft and patient survival, while minimizing the risks of adverse events and long-term complications. Based on the proceedings of an international gathering of nephrologists, cardiologists and surgeons at the inaugural PSI Forum meeting "Proliferation signal inhibitors in transplantation: questions at the cutting edge," this paper aims to provide both an evidence base and practical guidance for transplant physicians seeking to optimize their use of PSI treatment and highlights avenues of ongoing research into the clinical potential of this class of immunosuppressive therapy.