Engineering In Vivo Chimeric Antigen Receptor Macrophages (CARMs) using mRNA-exosomes for Cancer Immunotherapy

项目总结

PROJECT SUMMARY Chimeric antigen receptor (CAR) T cell therapy has revolutionized the treatment of hematologic cancers. However, for solid tumors, CAR T cells face challenges including intratumor heterogeneity, dynamic expression of target receptors, and often the inability for T cells to traffic to tumors to mediate the desired antitumor effect. In contrast to the lack of T cell infiltrates, many solid tumors are abundant in immune suppressive myeloid cells including macrophages. Therefore, converting these immune suppressive cells into tumoricidal phenotype represents a promising strategy for cell-based therapy. There are now strong interest in generating CAR macrophages in which autologous macrophages are transduced with CAR delivered by viral vectors ex vivo to enhance their phagocytosis, antigen presentation and cytokine producing capabilities following re-infusion. However, ex vivo preparation of CAR macrophages is complex, time consuming, and due to the non-dividing nature of macrophages, is often inefficient. With the recent advances in mRNA-based therapeutics, it is now possible to reprogram specific immune cell populations in vivo, thus eliminating the complex ex vivo production of autologous CAR cells. Our present proposal aims to propose an innovative strategy of generating CAR macrophages in vivo using mRNA-loaded exosomes to treat HER2 receptor positive breast cancer. This will be the first study to evaluate the feasibility of producing CAR macrophages in vivo using mRNA delivery platforms and assessing the antitumor efficacy of CAR macrophages for cancer immunotherapy. We hypothesize that our strategy represents a revolutionary way to produce CAR macrophages in vivo using CAR mRNA-loaded exosome and offers a promising new approach for cell therapy against solid tumors. Our previous study showed that we can efficiently produce mRNA-loaded exosomes to restore protein expression in solid tumors. Furthermore, our preliminary experiments showed that the exosomes loaded with HER2 CAR mRNA can produce CAR macrophages in vivo with enhanced effector functions. Our current study will test our overall hypothesis by using the following specific aims. In Aim 1, we will evaluate the dynamics and toxicity of CAR macrophage production in vivo using CAR mRNA exosomes. In Aim 2, we will evaluate transcriptomic and functional profiles of in vivo generated CAR macrophages, Finally, in Aim 3, we will assess the antitumor effect of in vivo generated CAR macrophages against both murine and human HER2 expressing breast cancer. If successful, our proposed research can overcome a major technical hurdle that is currently facing cell therapy. The mRNA exosome platform could potentially be expanded to other CAR constructs and greatly expand the potential utility of cell therapy for breast and other solid cancers.