Belatacept (Nulojix) in Renal Transplant Recipient With Mild Immunologic Risk Factor: a Pilot Prospective Study.

BACKGROUND: Antibody-mediated humoral rejection is currently a critical question in renal transplant recipient with immunological risk factors such as pre transplant donor-specific anti HLA antibodies (DSA). The immunosuppressive management of the patients is still not well defined and improving both short and long-term graft outcome remains a challenging question. Recent experimental data suggest that Belatacept could induce B cell anergy , induce regulatory B cell and decrease Ig production. These findings are strengthened by the results of both phase II and III clinical studies, showing a significant lower incidence of DSA in patients treated with Belatacept compared to recipients receiving a conventional immunosuppressive regimen with calcineurin inhibitors (CNI). Primary objective will be the incidence of clinical and subclinical humoral rejection (According to BANFF 2011 Criteria). Secondary objectives will include one-year graft and patient survival, renal function at M12 (MDRD), incidence of cellular rejection (M 12), level of proteinuria (M3 and M12) and DSA outcome (outcome of DSA MFI at JO, M3 and M12). Inclusion period will be of two years. DSA identification and quantitative analysis before and after transplantation will be centralized in only one HLA laboratory Unit (Hospital Saint Louis) for providing results homogeneity. According to previous clinical studies, the incidence of Acute Antibody Mediated Humoral Rejection is close to 20% in patients with mild immunological risk defined by the presence of DSA at the time of transplant with mean fluorescence intensity (MFI) between 1000 and 3000 (Luminex). In order to demonstrate a significant reduction (40%) of AAMR and sAAMR incidence, 91 patients will be included in this study. Results will be compared to a cohort matched for age, sex, immunological risk factor (DSA), time of transplant, transplant center and grafted with a similar immunosuppressive regimen including CNI instead of Belatacept