Introduction: Focal segmental glomerulosclerosis (FSGS) is a cause of end-stage renal failure that frequently recurs following renal transplant, often leading to early allograft loss. A recently published case series demonstrated that abatacept (a biologic fusion protein that binds B7-1) could potentially reverse proteinuria and podopathy in patients with recurrent FSGS after transplant. While abatacept is not clinically approved for transplant immunosuppression, belatacept (a closely related molecule which possesses an even higher avidity for B7-1) is approved for this indication. We sought to determine whether immunosuppression regimens containing belatacept could prevent FSGS recurrence in renal transplant recipients. Additionally, as the original clinical trials of belatacept excluded recipients with FSGS, we evaluated the efficacy of belatacept in this patient population as manifested in rejection rates and long-term graft function. Methods: Here we present the outcomes of 50 consecutive renal transplant recipients with FSGS who were treated with belatacept, comparing them to an earlier cohort of 17 FSGS recipients treated with conventional tacrolimus-based immunosuppression regimens. All patients received basiliximab induction and well as mycophenolate mofetil and steroids. Mean follow-up was 682 days (ranging from 24 to 1490 days). Kaplan-Meier survival curves were generated and significance determined by log-rank test. Results: The incidence of recurrent FSGS was almost identical in the transplant recipient cohort receiving belatacept and the cohort receiving tacrolimus (12% vs. 11.8%, p= 0.37). Similarly, there was no statistically significant change in the incidence of acute rejection. Differences in estimated glomerular filtration rates over three years of follow-up were also statistically non-significant between the tacrolimus and belatacept-treated renal allograft recipients. Conclusions: This case series is the largest reported experience using belatacept in transplant recipients with FSGS. Despite the promising earlier reported results with abatacept therapy, belatacept-based immunosuppression does not appear to protect against recurrent FSGS in renal transplant recipients. However, belatacept administration appears safe in this patient population as manifested by equivalent rejection rates and graft function compared to tacrolimus.

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