*Purpose: HLA identical (HLA ID) living donor kidney transplants (KTx) provide long-term survival with substantially reduced rejection risk; aspects that can be exploited in designing immunosuppression (IS) minimization regimens. In this study, we compared belatacept (Bela) and mycophenolate (MYC)-based monotherapy with standard of care (SOC) in HLA ID KTx using the institutional database linked to Scientific Registry of Transplant Recipients (SRTR).

*Methods: We performed a matched cohort study of 300 HLA ID KTx: 60 recipients assigned to either Bela- or MYC-based regimen per our institutional protocol(Figure1); 240 controls derived from SRTR as CNI-based SOC.

Predefined endpoints included a combinatorial primary outcome of patient survival, graft survival or rejection, and renal graft function as a secondary endpoint.

*Results: Our cohort consisted of 15, 45, and 240 patients in Bela, MYC, and SOC, respectively. Baseline demographics were similar between groups except for viral serologies (Table1). Death-censored (DC) graft survival [n(%)] was Bela 15(100);MYC 38(84);SOC 214(89), p=0.25. DC-graft loss related to rejection was 57% and 69% in MYC and SOC, respectively. Outcomes at Year(Y) 3 are summarized in Table2.

Figures2 to 4 show survival analyses with no significant difference, p>.05. A proportion of recipients who achieved eGFR≥60mL/min/1.73m² at Y1 was Bela 67%;MYC 33%;SOC 30%, p=0.29. This trend was maintained throughout the cohort period(Figure5).

*Conclusions: Bela monotherapy was associated with favorable outcomes and improved renal graft function, whereas higher graft loss was observed in MYC-based regimen. This initial experience with a belatacept-based regimen appears to provide an attractive alternative to current CNI-based IS protocols.

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