Introduction: Belatacept (B) is a co-stimulation inhibitor currently used as part of maintenance immunosuppression therapy in calcineurin free regimens for renal transplantation (RT). Compared with Cyclosporine based regimens, B has shown no efficacy inferiority and less nephrotoxicity. We compared a de novo B (BG) based regimen vs. Tacrolimus (FKG) in a 5 year, ambispective observational study.

Objective: To compare a B based regimen vs. Tacrolimus in terms of efficacy and safety.

Methods: We included donor’s (D) and baseline recipient’s (R) demographic data. Follow data involved, creatinine, estimated glomerular filtration rate (eGFR), proteinuria (UP), acute rejection (AR), adverse events (AE), patient (PS) and  death censored graft survival (DCGS). A D and R age and sex matched (1:1) sub analysis was performed between groups excluding living D RT. Differences were assessed using Student's t-test, Mann-Whitney U-test, chi-square test, or Fisher's exact tests, as appropriate. Survival curves were analyzed with Kaplan Meier.

Results: Before matching the study included 88 RT (BG: 25, FKG: 63).  R on BG were older (63±11 vs. 52±12, p<0.001), they received kidneys from deceased (92% vs. 68.3%, p 0.016) and older (54±16 vs. 51±13, p<0.001) D than FKG.  Delayed graft function was higher in BG (76% vs. 27%, p<0.001). Pre transplant panel reactive antibodies, donor specific antibodies, number of re-transplants or use of polyclonal antibodies as induction therapy were not different between groups (Figure1). After matching 23 R remained in each group. BG had significantly more extended criteria  D (91.3% vs. 30.4%, p<0.0001) and a higher incidence of DGF (73.9% vs 30.4%; p 0.003). For the rest of the variables groups were comparables (Figure 2). During the first year of follow-up of the matched cohorts, BG showed higher creatinine values (1.65±0.58 vs. 1.33±0.39, p 0.036) and lower eGFR values (43.2±14 vs. 54.9±18, p 0.026). This difference disappeared with a trend towards reversal at the fifth year, creatinine values (1.17±0.25 vs. 1.55±0.59, p0.12) and eGFR (57.1±16 vs. 50.4±24, p 0.51) respectively. BG showed a lower incidence of PTDM (8.7% vs 39.1%, p 0.016) and a trend towards lower AR rate (17.4% vs 39.1%, p 0.095). The incidence of CMV was higher in BG (55% vs. 23.8%, p < .041). There were no differences in the incidence of  hypertension (HTN), malignancy, or infections between the groups (Figure 2). Patient survival was 90% and DCGS was 95% at one year with no differences between groups during follow-up.

Conclusions: In this study Belatacept showed comparable efficacy results with Tacrolimus with a trend towards a better renal function, similar patient survival and DCGS. Belatacept showed lower incidence of  PTDM and higher incidence of CMV infection compared with Tacrolimus.