Enhance Cancer Therapeutics with 3-in-1 CAR T Cells

PROJECT SUMMARY Recent evidence highlights the significant role of tumor-associated myeloid cells (TAMCs), including tumor- associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs), in promoting cancer immunosuppression and progression. In glioblastoma (GBM) and certain other cancers, TAMCs can constitute up to 50% of the tumor's mass, playing pivotal roles in dampening the immune response and adversely affecting patient survival. Thus, targeting TAMCs presents a promising strategy to overcome the limitations of current cancer treatments. However, drug development in this area remains underexplored. Our research focuses on the leukocyte-associated immunoglobulin-like receptor 1 (LAIR1), which is prominently expressed on TAMs and is crucial in mediating their immunosuppressive function. We have identified a previously unrecognized immunosuppressive circuit involving LAIR1, Factor XIII A (FXIII-A), and Collagen IV across various cancer types. LAIR1 activation prompts TAMs to release FXIII-A around tumor cells, leading to increased deposition and structural organization of Collagen IV, shielding tumors from immune attacks. Inhibiting LAIR1, either through genetic knockout (LAIR1-/-) or antibody blockade (aLAIR1), disrupts this immunosuppressive pathway, resulting in enhanced populations of peripheral and tumor-infiltrating memory CD8 T cells, a phenotypic shift of TAMs toward an M1 profile, and reduced tumor-collagen deposition. These collective effects contribute to normalizing the TME and promote more effective interactions between T cells and tumor cells, leading to a robust antitumor response. Notably, aLAIR1 demonstrates enhanced antitumor efficacy as a standalone treatment or combined with Chimeric Antigen Receptor (CAR) T cell therapy in preclinical models resistant to chemo/radiation/anti-PD-1 treatment. These findings position aLAIR1 as a promising strategy for cancer immunotherapy. However, the blood-brain barrier (BBB) and tumor physical barrier (TPB) pose a significant challenge for developing effective antibody therapies for brain tumors and other cancers. This study aims to overcome these barriers by evaluating the antitumor efficacy and toxicity of our 3-in-1 triple- functional CAR platform, which combines 3 critical functions: precise tumor targeting, enhanced CAR T-cell tumor trafficking/penetrating, and inhibition of TAMCs through LAIR1 signaling blockade. These functions aim to reshape the TME and enhance antitumor response. Two aims are proposed: Aim 1: Testing antitumor efficacy of the CAR T cells in a clinically relevant GBM model. Aim 2: Conducting a pilot toxicology study of the 3-in-1 CAR T cells. Successful completion of this study will validate the capability of the 3-in-1 CAR T cells to overcome the BBB and TPB. Moreover, it will lay the groundwork for phase II, an IND-enabled study aimed at clinical translation and technology commercialization.