Biopsy-Proven T-Cell Mediated Rejection After Belatacept Rescue Conversion: A Multicenter Retrospective Study

After kidney transplantation, conversion to belatacept is a promising alternative in patients with poor graft function or intolerance to calcineurin inhibitors. The risk of acute rejection has not been well described under these conditions. Here we present a retrospective multicenter study investigating the occurrence of acute rejection after conversion in 901 patients (2011-2021). The incidence of cellular and humoral rejection was 5.2% and 0.9%, respectively. T-cell mediated rejection (TCMR) occurred after a median of 2.6 months after conversion. Out of 47 patients with TCMR, death-censored graft survival was 70.1%, 55.1% and 50.8% at 1 year, 3 years and 5 years post-rejection, respectively. Eight patients died after rejection, mainly from infectious diseases. We compared these 47 patients with a cohort of kidney transplant recipients who were converted to belatacept between 2011 and 2017 and did not develop rejection (n = 238). In multivariate analysis, shorter time between KT and conversion, and the absence of anti-thymocyte globulin induction after KT were associated with the occurrence of TCMR after belatacept conversion. The occurrence of rejection after conversion to belatacept appeared to be less frequent than with <i>de novo</i> use. Nevertheless, the risk of graft loss could be significant in patients with already low renal function.