GENETIC ENGINEERING STRATEGIES FOR EXPANDING THE THERAPEUTIC INDEX OF CHIMERIC ANTIGEN RECEPTOR CELLULAR IMMUNOTHERAPIES

Chimeric antigen receptor (CAR)-T cells are a groundbreaking gene therapy that redirects a patient's own immune cells to target their cancer. Despite the success of CAR-T cell therapies in hematological malignancies, clinical deployment against solid tumors has been limited due to low therapeutic efficacy or dose-limiting toxicity. A key challenge has been to develop therapies that can trigger potent, yet manageable, immune responses capable of eliminating highly heterogeneous and immunosuppressive tumor cell populations. Here, we harness multiple genetic approaches to develop a solid tumor therapy that considers both safety and efficacy.
First, we develop a genetic platform that combines autonomous antigen-induced production of an accessory molecule, with constitutive CAR expression in a single lentiviral vector called UniVect. The superior utility of UniVect is demonstrated using inducible IL-12 in comparison to current expression systems that rely on constitutive transgene expression or multiple viral vectors, resulting in unregulated response and product heterogeneity, respectively. Next, we screen scFvs targeting the highly prevalent and oncogenic KRAS mutations presented by peptide-MHC complexes and incorporate these neo-antigen binders into CAR-T cells (mKRAS NeoCARs). Furthermore, we enhance the in vivo efficacy and safety profile of KRAS NeoCARs via integration with the UniVect platform and T cell receptor deletion. In doing so, we demonstrate simple, multiplex, and modular genetic engineering of armored CAR-T cells. Together, processes expand the therapeutic index of cellular immunotherapies that target solid tumors and provide a foundation for a more clinically actionable next-generation cellular immunotherapy.