Single-Center Outcomes of Conversion to Belatacept in Kidney Transplant Recipients.

Belatacept (Bt) conversion is associated with increased rejection risk in kidney transplant patients (KTxP). The study included patients who underwent kidney transplant and were converted to Bt. Induction was given, followed by maintenance with a calcineurin inhibitor (CNI), antimetabolite, and steroid. CNI was tapered post-Bt based on patient risk. Patients were divided into three cohorts: rejection prior to conversion (RP), no rejection (NR), and rejection after conversion (RA). The primary outcome was biopsy-proven acute rejection (BPAR) at 1 year post conversion. Secondary outcomes included change in estimated glomerular filtration rate (eGFR) and 12-month patient and graft survival. Concordance with dd-cfDNA, MMDx, and eplet matching was analyzed for each BPAR incidence. Out of 69 patients included in the study, 10.1% had BPAR post conversion. RP patients' eGFR was lower at 12 months post conversion, median 23 mL/min (IQR 16-45) compared to NR and RA patients, 44 mL/min (31-66) and 39 mL/min (34-50) respectively. Dd-cfDNA was elevated prior to biopsy in all RA biopsies. Histopathologic findings differed from MMDx reports 75% of the time. Rejection prior to Bt conversion is associated with lower eGFR, whereas rejection after Bt conversion maintains an eFGR similar to those without rejection. Bt conversion should be considered safe and effective.