Belatacept
Belatacept is a soluble fusion protein combining the human IgG1 Fc domain with the modified extracellular domain of cytotoxic T lymphocyte–associated antigen 4 (CTLA4). As a CD28 homolog it binds to CD80 and CD86 on the antigen-presenting cells, thus inhibiting CD28-mediated T cell co-stimulation and thereby selectively preventing the activation of T cells. Belatacept is approved for rejection prophylaxis in renal transplant recipients as an alternative to calcineurin inhibitors (CNI) and in combination with basiliximab, mycophenolate and glucocorticoids. Further clinical trials have tested alternative approaches like belatacept plus mTOR inhibitor, weaning of glucocorticoids and the replacement of basiliximab with alemtuzumab in a belatacept based regimen. A common finding in these studies is a somewhat increased incidence of acute rejections but the decline in renal function and other typical CNI related adverse effects has been avoided.