Peptide-MHC-targeted retroviruses enable in vivo expansion and gene delivery to tumor-specific T cells

Tumor-infiltrating-lymphocyte (TIL) therapy has demonstrated that endogenous T cells can be harnessed to initiate an effective anti-tumor response. Despite clinical promise, current TIL production protocols involve weeks-long ex vivo expansions which can affect treatment efficacy. Therefore, additional tools are needed to engineer endogenous tumor-specific T cells to have increased potency while mitigating challenges of manufacturing. Here, we present a strategy for pseudotyping retroviral vectors with peptide-major histocompatibility complexes (pMHC) for antigen-specific gene delivery to CD8 T cells and examine the efficacy of these transduced cells in immunocompetent mouse models. We demonstrate that pMHC-targeted viruses are able to specifically deliver function-enhancing cargoes while simultaneously activating and expanding anti-tumor T cells. The specificity of these viral vectors enables in vivo engineering of tumor-specific T cells, circumventing ex vivo manufacturing processes and improving overall survival in B16F10-bearing mice. Altogether, we have established that pMHC-targeted viruses are efficient vectors for reprogramming and expanding tumor-specific populations of T cells directly in vivo , with the potential to substantially streamline engineered cell therapy production for a variety of applications.