Multiplex gene-editing strategy to engineer allogeneic EGFR-targeting CAR T-cells with improved efficacy against solid tumors

Chimeric Antigen Receptor (CAR) T cells have induced remarkable clinical responses in patients with hematological cancers. However, CAR T-cell therapies against solid tumors have not elicited similar outcomes since immunosuppressive barriers in the tumor microenvironment attenuate anti-tumor activity. Here, we describe a multifaceted approach to engineer allogeneic CAR T-cells resistant to both biochemical (hypoxia-adenosinergic) and immunological (PD-L1 and TGF-β) inhibitory signaling using an adenine base editor and a CRISPR-Cas12b nuclease. The resulting EGFR-targeting CAR T-cell product comprised a combination of six gene edits designed to evade allorejection (B2M, CIITA), prevent graft-versus-host disease (CD3E) and overcome biochemical (ADORA2A) and immunological (PDCD1, TGFBR2) barriers in solid tumor microenvironment of subcutaneously grown EGFR+ human lung tumor xenografts. This combinatorial genetic disruption enhances CAR T cell effector function and anti-tumor efficacy leading to improved tumor elimination and survival in xenograft and humanized mouse solid tumor models. Our strategy confers CAR T cells resistance to multiple clinically relevant inhibitory signaling pathways that are amplified in hypoxic tumor areas and may improve the therapeutic potential of CAR T-cells against solid tumors. Resistance signaling in the tumor microenvironment limits CAR T cell therapy in solid tumors. This study introduces a multiplex engineered CAR T cell strategy using six gene edits to overcome multiple inhibitory barriers.