Abstract 3612: Preclinical & clinical activity of autologous mRNA engineered chimeric antigen receptor monocytes for targeted cancer immunotherapy

Abstract Introduction: The tumor microenvironment (TME) is a dynamic and multifaceted system that comprises largely myeloid lineage immune cells including neutrophils, macrophages, dendritic cells and monocytes. When activated, these cells are can effectively infiltrate TME and orchestrate anti-tumor immune response. Reprogramming myeloid cells by arming them with a tumor specific chimeric antigen receptor (CAR) presents an attractive strategy to overcome current limitations in solid tumor treatment. In this study, we present the isolation and mRNA-based engineering of monocytes with chimeric antigen receptors (CARs), followed by their in vivo application for cancer treatment in rodent models and in human T cell lymphoma patients. Results: Engineered monocytes demonstrated the abilities to infiltrate the TME, undergo activation, and differentiate into macrophages and dendritic cells. Upon CAR activation, these reprogrammed myeloid cells utilized both direct and indirect mechanisms to eliminate tumor cells. This included direct tumor cell killing through phagocytosis and TNF-associated mechanisms. Furthermore, engineered monocytes exhibited the capacity to recruit natural killer (NK) cells and T cells to the TME. In the case of T cells, these engineered myeloid cells facilitated the presentation of neoantigens to T cells and stimulate an adaptive immune response. In patients with T cell lymphoma, treatment with engineered monocytes expressing a CAR targeting CD5 exhibited a favorable safety profile and was associated with TME remodeling, expansion of novel T cell clones, and promising survival outcomes. Conclusions: These findings underscore the potential of reprogrammed myeloid cells as a novel avenue for cancer immunotherapy, offering hope for improved treatments and outcomes in the fight against cancer. Citation Format: Yuxiao Wang, Michele Gerber, Michael Gorgievski, Josephine D'Alessandro, Neha Diwanji, Ronald Vale, Siddhartha Mukherjee, Daniel Getts. Preclinical Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 3612.