Novel immunosuppressive agents in kidney transplantation

The last several decades have seen a substantial decrease in the prevalence of acute allograft rejection in kidney transplant recipients, while equivalent improvements in long-term graft function have not been realized. As a result, the primary focus of new immunosuppressive drug development has expanded to include ease of use, improved side effect profiles, and reduced nephrotoxicity in addition to the more traditional goal of improved short-term outcomes. A number of novel drugs are currently under investigation in Phase I, II, or III clinical trials primarily to replace the nephrotoxic but highly effective calcineurin inhibitors. ISA247 (voclosporine) is a cyclosporine (CsA) analog with reduced nephrotoxicity in Phase III study. AEB071 (sotrastaurin), a protein kinase C inhibitor, and CP-690550, a JAK3 inhibitor, are small molecules in Phase II studies. Everolimus is derived from the mTOR inhibitor sirolimus and is in Phase III study. Belatacept is a humanized antibody that inhibits T-cell costimulation and has shown encouraging results in multiple Phase II and III trials. Alefacept and Efaluzimab are humanized antibodies that inhibit T-cell adhesion and are in Phase I and II clinical trials. This article reviews the mechanisms of action as well as published and preliminary results of the Phase I-III clinical trials involving these novel immunosuppressive agents.