Belatacept: a novel biologic for maintenance immunosuppression after renal transplantation.

In the past decade, the availability of new immunosuppressive maintenance therapies for use in solid organ transplantation has remained limited. Patients and clinicians have relied on immunosuppressive drugs that require a significant amount of therapeutic monitoring and are associated with a variety of adverse effects that affect both quality of life and allograft function. Belatacept is an investigational intravenous biologic agent for long-term use in renal transplant recipients. The costimulatory pathway (signal 2) of T-cell activation and proliferation is produced by stimulation of the T-cell surface marker, CD28, and is essential to the immune system's cellular response and ability to recognize an allograft as foreign. Belatacept is a potent antagonist of B7-1 (CD80) and B7-2 (CD86) ligands present on antigen-presenting cells that are responsible for activation of CD28. Recent phase III trials describe various dosing strategies of belatacept versus a standard cyclosporine protocol in recipients of both living- and deceased-donor renal transplants, as well as in patients receiving kidneys transplanted from extended-criteria donors. Compared with cyclosporine, belatacept has been shown to be noninferior in both patient and allograft survival rates. However, the rate of biopsy-proven acute cellular rejection occurred more frequently in the belatacept groups. Also, compared with standard calcineurin-based regimens, the risk of posttransplant lymphoproliferative disorder is increased in patients receiving belatacept, with the greatest risk in transplant recipients who are Epstein-Barr virus seronegative before transplantation. However, this investigational immunosuppressive agent may avert common adverse effects experienced with standard immunosuppressive protocols including renal dysfunction, metabolic disorders, neurotoxicities, glucose abnormalities, and cosmetic effects. More data on the long-term risks of belatacept are needed to better define its role as immunosuppressive maintenance therapy. Aside from an increased risk of malignancy, belatacept's limited adverse-effect profile and convenient dosing strategy may make it an attractive option for immuno-suppressive maintenance for both the patient and clinician.