Abatacept (trade name Orencia, Bristol-Myers-Squibb), a fusion protein of a Fc fragment (human IgG1 isotype) and the extracellular domain of CTLA-4, can be used to extend graft survival while limiting the toxicity generated by standard immune suppressing regimens, such as calcineurin inhibitors. Abatacept binds to CD80 (B7-1) with more avidity than to CD86 (B7-2). Abatacept inhibits the costimulation of T cells. Abatacept differs from belatacept (trade name Nulojix) by only 2 amino acids.The CTLA-4 protein is important for T-cell costimulation and selectively blocks the process of T-cell activation.
