Immune repertoire remodeling following B cell-targeted CAR T cells for induction of renal allograft tolerance in non-human primates

Kidney transplantation is the treatment of choice for patients with end-stage kidney disease. Potent T cell directed immunosuppression has led to excellent short-term allograft survival. However, chronic immune rejection remains a significant challenge as rejection constitutes the most common reason for kidney failure and return to dialysis. Induction of immune tolerance serves the dual benefits of preventing rejection of the kidney and salvage of recipients from toxicities associated with chronic immunosuppression. Our preliminary studies in a murine model indicated a requisite role of B cell antigen presentation in activation of alloreactive CD4 T lymphocytes. Therefore, our contention is that the induction of robust transplantation tolerance will require unresponsiveness at the level of both the B- and T-cell compartments. As such, we performed preclinical trials of kidney transplantation in Cynomolgus macaques utilizing a combined induction immunotherapy regimen, which included a CD20-specific B cell depleting monoclonal antibody (Rituximab) and T cell depletion with Thymoglobulin. This regimen led to marked prolongation of allograft survival in some recipients. However, a majority of allografts succumb to immune rejection with development of donor specific antibodies. Importantly, we demonstrated that prolonged survival was correlated with the re-emergence of the B cells with an immature/naive phenotype. In animals with early allograft loss, the re-emerging B cell compartment was predominantly composed of activate/mature B cells, suggestive of residual Rituximab-resistant tissue-resident B cell clones. Therefore, we contend that stringent B cell depletion is a prerequisite for robust B and T cell repertoire modification toward a tolerant state. The present application utilizes a CD20-targeted CART cell therapy to achieve stringent B cell depletion permitting regeneration of the B cell compartment in the presence of the kidney allograft to recapitulate the ontogeny of B cell tolerance. Importantly, since B cells are potent APCs for T cell priming, the impact of B cell repertoire modification has the potential to provide tolerogenic signals to a responding allo-reactive T cell pool. We test this concept in the setting of kidney allo-transplantation in Cynomolgus monkeys. Mechanistic studies will interrogate both B and T cell alloimmunity at the cellular and molecular levels. Finally, we will develop an mRNA-LNP based method of in vivo CAR T cell generation to facilitate clinical translation. Overall, this proposal develops new therapeutics and introduces novel technologies to the NHP model with the ultimate goal of clinical translation. Project Number: 1R01AI190177-01 | Fiscal Year: 2025 | NIH Institute/Center: National Institute of Allergy and Infectious Diseases (NIAID) | Principal Investigator: Ali Naji (+4 co-PIs) | Institution: UNIVERSITY OF PENNSYLVANIA, PHILADELPHIA, PA | Award Amount: $1,648,086 | Activity Code: R01 | Study Section: Immunobiology of Transplantation and Alloimmunity Study Section[ITA] View on NIH RePORTER: https://reporter.nih.gov/project-details/1R01AI19017701