Immunosuppression in liver transplantation: beyond calcineurin inhibitors.

Although calcineurin inhibitors (CNIs) remain the mainstay of immunosuppression in liver transplantation (LTX), their long-term toxicity significantly contributes to morbidity and mortality. The elucidation of mechanisms of alloimmunity and leukocyte migration have provided novel targets for immunosuppression development. The toxicities of these agents differ from that of the CNI and act additively or synergistically. CNI avoidance protocols in LTX have not been achieved routinely; however, pilot trials have begun to delineate the limitations and promises of such approaches. CNI-sparing protocols appear to be much more promising in balancing the early need for minimizing rejection while tapering doses and minimizing long-term toxicity.