Treatment of Antibody-Mediated Rejection (ABMR) With CarBel

This is a prospective, multicenter, open-label study evaluating the safety of carfilzomib and belatacept in kidney transplant recipients with donor-specific antibody-associated graft injury. Twenty-five participants will receive steroid pulse/taper, carfilzomib, belatacept, tacrolimus, mycophenolate, and prednisone according to protocol-defined dosing and maintenance immunosuppression. Participants will be followed for 12 months after initiation of investigational therapy, with protocol biopsies performed at 3 months and 12 months after start of investigational therapy. Participants who discontinue study treatment without withdrawing informed consent will continue follow-up to end of study.