Gene editing holds the promise of enhancing the precision and safety of anti-HIV gene therapies based on engineering hematopoietic stem and progenitor cells (HSPC), in order to recreate elements of the Berlin Patient cure. Targeted nuclease technology is already being used to exploit NHEJ-mediated repair of DNA breaks and thereby disrupt the CCR5 gene, which mimics one aspect of his cure. However, extending this treatment to non- cancer patients, receiving engineered autologous HSPC, will likely need to include other approaches. To do this, we are exploiting the alternate pathway of DNA break repair based on homology-directed repair (HDR). This can be used to introduce gain-of-function mutations into cellular restriction factors, or to direct the controlled secretion of soluble anti-viral factors, including the broad entry inhibitor eCD4-Ig. Moreover, the site-specific insertion at eCD4-Ig at the CCR5 locus would combine HIV-resistance with systemic protection and thereby provide a combinatorial anti-HIV approach. In the current proposal we aim to continue to improve the safety and efficacy of gene editing in HSPC, and to apply the technology to provide both local and systemic HIV resistance. We will combine our established anti-HIV approaches with a new direction to engineer production of broadly neutralizing antibodies, and thereby provide a novel synthetic immune capability. Individual strategies and combination approaches will be evaluated in appropriate humanized mouse models, to evaluate their impact on HIV infection and the latent reservoir.
Genetic modification of hematopoietic stem and progenitor cells is being considered as a way to mimic elements of the Berlin Patient cure. In this proposal we will enhance the efficiency and safety of modifications based on genome engineering and evaluate combinations of approaches that could be combined to suppress HIV and achieve a cure.
