Late Conversion to Belatacept After Kidney Transplantation: Outcome and Prognostic Factors.

BACKGROUND: Conversion to belatacept at a later point after kidney transplantation (KT) as a rescue therapy has been shown to be beneficiary in an increasing number of patients, but prognostic factors for a favorable outcome have never been investigated.

METHODS: The present study analyzed all KT patients after late conversion to belatacept in a single center regarding graft survival and changes in estimated glomerular filtration rate (eGFR), proteinuria, and mean fluorescence intensity (MFI) of donor-specific antibodies (DSA).

RESULTS: A total of 69 KT patients were converted to belatacept. eGFR increased from 28.9 ± 18.2 mL/min/1.73 m2 at time of conversion to 34.8 ± 20.1 mL/min/1.73 m2 after 18 months (P = .025). After conversion, 26/69 patients (37.7%) showed a sustained increase in eGFR of >5 mL/min/1.73 m2 after 12 months and were defined as responders. All other patients (43/69, 62.3%) were defined as nonresponders. In multivariate analysis, nonresponders presented with significantly higher proteinuria (552 ± 690 vs 165 ± 158 mg/L; P = .004) at the time of conversion. Changes of eGFR from before conversion and the time of conversion were similar in both subgroups (-5.7 ± 9.2 and 29.2 ± 17.3 mL/min/1.73 m2 in responders and -4.6 ± 10.7 and 28.7 ± 19.0 mL/min/1.73 m2 in nonresponders). HLA antibody panel reactivity did not change after conversion. DSA-MFI was higher in nonresponders (7,155 ± 6,785) than in responders (2,336 ± 2,173; P = .001). One patient (1/69, 1.4%) developed de novo DSA after conversion, and no antibody-mediated rejection was diagnosed within 1,540 treatment months.

CONCLUSIONS: Late conversion to belatacept is beneficiary for a subgroup of patients, with lower proteinuria at the time of conversion being an indicator for a favorable outcome.