*Purpose: The use of belatacept with basiliximab induction and maintenance MMF/prednisone when compared to cyclosporine is associated with superior long-term patient and graft survival but a higher 1-year acute rejection rate. In developing a de novo belatacept protocol we hypothesized that the use of belatacept with rATG induction and maintenance MMF/prednisone would improve efficacy and maintain safety.

*Methods: Retrospective single center analysis of the first 19 EBV seropositive, low immunologic risk kidney transplant recipients with at least 18-months of follow up treated with belatacept combined with rATG induction (4.5 mg/kg) and MMF maintenance (750 mg twice daily dose adjusted for leukopenia and side effects) with maintenance prednisone. Biopsies were performed for cause. GFR was estimated by MDRD. Outcomes of interest: 18-month eGFR, acute rejection rate, patient and graft survival, development of infections and PTLD.

*Results: The cohort was 63% male, 58% Caucasian, 26% African-American, 16% Asian, with a mean age of 47.6 (SD 13.1) years and overall low immunologic risk (18 patients with a cPRA of 0%; 1 patient with a cPRA of 99% but no DSA) with a mean of 4.2 (SD 1.8) HLA mismatches. GN was the most common cause of ESRD (36.8%) followed by DM (31.6%). 13 patients received a deceased donor transplant (mean KDPI 37%); 52.6% developed DGF. The mean 6- and 18-month eGFR was 60.7 (SD 18.4) and 68.1 (SD 18.4) mL/min/1.73 m², respectively. Three patients developed acute rejection (15.8%), 1 ACR 2a on POD 49 complicated by recurrent rejection (ACR 3) and graft loss on POD 88 associated with non-compliance. Two developed ACR 2b, one on POD 29 (18-month eGFR 68 mL/min/1.73 m²) and the other on POD 110 (18-month eGFR 55 mL/min/1.73 m²). There were no patient deaths. One patient developed CMV viremia, 2 patients developed BK viremia, and 5 patients experienced a UTI. There were no cases of PTLD.

*Conclusions: A de novo belatacept based regimen with rATG induction and maintenance MMF/prednisone resulted in a numerically lower ACR rate compared to results found in published phase 3 trials but still higher than typically seen with a tacrolimus-based regimen. Overall the 18-month eGFR was excellent and improved over time. There was an acceptable safety profile with a low incidence of CMV and BKV and no episodes of PTLD.

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