Epitope-engineered HSCs to permit CAR-T cell-mediated CD4-depletion for HIV cure

About This Grant

Project Summary HIV cure has been achieved almost exclusively in individuals undergoing allogeneic hematopoietic stem cell transplantation (HSCT) for hematologic malignancies using homozygous donors for the CCR5D32 deletion. Although these cases demonstrate that installation of an HIV-refractory immune system is feasible, broader clinical translation is limited by viral rebound from residual reservoir cells, outgrowth of viruses using alternative co-receptors, and the substantial morbidity associated with allogeneic transplantation. These limitations highlight the need for approaches that both protect newly generated immune cells from infection and actively eliminate persistent HIV-infected cells. We propose autologous HSCT-based strategies that integrate precise genome editing with targeted cellular immunotherapy. Using base editors, we introduce functionally silent missense mutations in CD4, the primary HIV entry receptor, to generate immune cells broadly resistant to both CCR5- dependent and CCR5-independent HIV strains while preserving CD4-dependent immune function. In parallel, we engineer additional CD4 variants that render base-edited cells resistant to CD4-specific CAR T cell-mediated depletion, thereby enabling CAR T cells to selectively eliminate residual wild-type CD4+ cells, including those harboring HIV reservoirs, following HSCT. These approaches establish a protected immune compartment while permitting targeted eradication of reservoir cells that drive viral rebound after antiretroviral therapy interruption. We will test the central hypothesis that combining autologous HSCT with CD4-targeted base editing will both prevent infection by HIV variants with distinct co-receptor tropisms and enable CAR T cells to eliminate persistent infected cells, thereby sustaining viral control while preserving immune competence Aim 1: Develop a CD4-modified HSCT approach to prevent HIV infection while preserving CD4+ immune reconstitution. Aim 2: Develop a CD4-modified HSCT approach enabling CAR T cell elimination of residual HIV-infected cells while preserving CD4+ immune reconstitution.