Assessment of Biomarker-Guided CNI Substitution In Kidney Transplantation

Observational Study: Enrolling 800 adult first time kidney transplant recipients. Consent and enrollment will be targeted to occur pre- or post-kidney transplant during the initial hospitalization. All subjects enrolled in the study will be followed observationally to evaluate HLA-DR/DQ molecular mismatched (mMM) as a risk-stratifying prognostic biomarker. This prospective, multi-center, observational study of 800 kidney transplant recipients at clinically low risk for alloimmune memory (DSA negative pre-kidney transplant) who are initiated on standard of care (SOC) therapy will be used to satisfy the FDA requirement to prospectively evaluate the HLA mMM score as a prognostic biomarker for post-kidney transplant outcomes in a real-world cohort. Donor-recipient HLA-DR/DQ mMM score will be determined at enrollment and recipients will be followed over 24 months post- kidney transplant for primary alloimmune events (i.e., T cell Mediated Rejection (TCMR), DSA, and Antibody Mediated Rejection (ABMR) ). Nested RCT (SOC versus conversion to abatacept): We will follow subjects in the Observational Study for the initial 6 months to identify those who meet the stringent "immune-quiescent" randomization criteria: absence of biopsy proven acute rejection (BPAR) on a for-cause or 6-month surveillance biopsy; and absence of DSA. In addition, these subjects must have absence of infection (e.g., BKV/CMV), and be on at least MMF ≥500 mg p.o. bid at the time of randomization. From this "immune-quiescent" group those individuals with a low or intermediate HLA-DR/DQ mMM score will be eligible for the Nested RCT. 300 eligible subjects will be randomized 2:1 to abatacept or SOC in the randomization phase (Abatacept arm: 200 vs. SOC arm: 100) to have adequate power for detecting differences between the treatment groups. Subjects enrolled into the trial's screening phase (0-6 months post-transplant) of the Observational Study will identify at least 360 kidney transplant recipients who exhibit immune quiescence and who meet the 6-months post-kidney transplant eligibility criteria for the Nested RCT. These individuals will be re-consented prior to randomization at 6-months post-kidney transplant.