Induction of immune tolerance in living related human leukocyte antigen–matched kidney transplantation: A phase 3 randomized clinical trial

This phase 3 multicenter, randomized, controlled clinical trial evaluated investigational cellular product (MDR-101) to produce immune tolerance vs standard of care, in kidney transplant recipients. Adult recipients of kidneys from 2-haplotype human leukocyte antigen-matched living siblings were randomized 2:1 to treatment (n = 20) or control (n = 10). The MDR-101 product was from the same kidney donor. Treatment recipients received a nonmyeloablative conditioning protocol with rabbit-antithymocyte globulin and low-dose total lymphoid irradiation (10 fractions). MDR-101 was infused (day 11). Steroids were withdrawn by day 10 and mycophenolate by day 39. Tacrolimus was continued until day 180 and tapered to withdrawal 1-year posttransplant if donor hematopoietic mixed chimerism was ≥5%. Controls received immunosuppression (IS) per institutional standard of care. Twenty recipients received the MDR-101 infusion, and none developed graft versus host disease. Nineteen (95%) successfully discontinued all IS approximately 1 year after kidney transplant. Fifteen (75%) reached the primary study endpoint of IS-free for >2 years. Four resumed IS: 1 with recurrent immunoglobulin A nephropathy; 1 with recurrent immunoglobulin A nephropathy and rejection; 1 with rejection; and 1 with borderline biopsy changes. Kidney transplant recipients receiving MDR-101 achieved donor mixed chimerism and functional immune tolerance for greater than 2 years with no death, graft loss, DSA, or graft versus host disease and demonstrated improved quality of life compared to standard treatment.