P1772CONVERSION TO BELATACEPT IMPROVES RENAL GRAFT FUNCTION OF PATIENTS WITH SEVERE HISTOLOGICAL AND FUNCTIONAL INVOLVEMENT. LONG-TERM UNICENTRIC EXPERIENCE

Background and Aims Belatacept selectively blocks the costimulation signal of T cells. Its use, both de novo and in conversion, is associated with a better renal graft function compared to the regimens that include a calcineurin inhibitor (CNI). We expose our experience with belatacept as a rescue therapy in patients who present moderate-severe dysfunction after renal transplantation and compare the evolution with those patients who received the contralateral kidney graft without change to belatacept. Method Adult kidney transplanted patients, with graft dysfunction and renal biopsy with CNI toxicity or chronic vascular lesions who are changed from CNI to belatacept were included. Efficacy (creatinine, proteinuria, TFGe, acute rejection tested by biopsy, anti HLA) and safety (adverse events, tumors or infections) variables were recorded before and after the change. Results 11 patients were included. The change to belatacept was made at a median of 13 months from the transplant (range 1-62 months) and the duration of the treatment ranged between 6 and 74 months. Renal function improved from a mean creatinine of 3.04±1.34 mg/dl before the change to 1.9±0.3 mg/dl at 6 and 12 months after conversion (p = 0.016), being the last average creatinine (December 2019) of 1.7±0.3 mg/dl. Belatacept was withdrawn in one case, at one year, due to the development of specific donor antibodies without evidence of acute rejection. There were no cases of post-transplant lymphoproliferative syndrome. Two patients developed VBK replication controlled with immunosuppression modification and three patients developed CMV infection controlled with valganciclovir. There was no episode of acute rejection after conversion. In 5 cases the contralateral kidney graft was not implanted, while in 6 cases it was implanted in another recipient who was not given belatacept and was taken on CNI therapy. The last average creatinine (December 2019) of patients without belatacept was 3.3±1.6 mg/dl vs. 1.6±0.2 mg/dl in patients with belatacept (p = 0.03). Conclusion The change to belatacept improves the renal function of all patients, even in those with severe histological and functional involvement. The improvement of renal function remains stable in the medium/long term and is significantly better than the renal function of patients with CNI.