Biological agents in kidney transplantation: belatacept is entering the field.

IMPORTANCE OF THE FIELD: Kidney transplantation is the best treatment for end-stage kidney-disease patients. However, despite major breakthroughs in the last decades, and the progresses made with immunosuppressants, the long-term results still need to be improved. This is related to the increased risk of cardiovascular mortality, de novo post-transplant malignancies, and chronic kidney disease within the allograft. The last is multifactorial and includes immunological and non-immunological factors. Amongst the last is the calcineurin inhibitor (CNI) (cyclosporine A (CsA) and tacrolimus)-related nephrotoxicity. Kidney-allograft function at 1-year post-transplantation is a good surrogate marker of long-term allograft survival. AREAS COVERED IN THIS REVIEW: Cytotoxic T-lymphocyte-associated antigen 4 (CTLA4)-Ig, a fusion protein, presents as abatacept, which conserves the natural structure of CTLA4, and belatacept, which has enhanced activity thanks to two amino-acid substitutions. Abatacept and belatacept block CD86-CD28 interaction, but belatacept blocks them more powerfully. Abatacept is already approved for the treatment of rheumatoid arthritis and is marketed as Orencia(®) (Bristol-Myers Squibb, Princeton, NJ, USA), whereas belatacept is not yet approved. Herein, we review the current data available on the use of belatacept in Phase II and III kidney-transplantation trials. Note, though, that data from belatacept Phase II liver transplantation trials are not yet available. WHAT THE READER WILL GAIN: The results show in de novo kidney transplant patients that as compared to CsA-treated patients, belatacept-treated patients showed: i) a significant better allograft function both at 1- and 2- year post-transplantation and ii) better cardiovascular and metabolic profiles. Regarding the safety data, Epstein-Barr virus (EBV) seronegative belatacept-treated patients experience more post-transplant lymphoproliferative disorders than the EBV seropositive belatacept-treated patients and the CsA-treated patients. TAKE HOME MESSAGE: CNIs are potent immunosuppressants but have some degree of nephrotoxicity. Therefore, it is important to have strong data showing that belatacept-based therapy is as efficient as CsA-based therapy, but displaying at both 1- and 2-year post-transplantation a better allograft function, which might translate in the long-term into longer allograft survival.