Adoptive T-cell therapy (ACT) is an emerging paradigm in which T cells are genetically modified to target cancer-associated antigens and eradicate tumors. However, challenges treating epithelial cancers with ACT reflect antigen targets that are not tumor-specific, permitting immune damage to normal tissues, and preclinical testing in artificial xenogeneic models, preventing prediction of toxicities in patients. In that context, mucosa-restricted antigens expressed by cancers exploit anatomical compartmentalization which shields mucosae from systemic antitumor immunity. This shielding may be amplified with ACT platforms employing antibody-based chimeric antigen receptors (CARs), which mediate MHC-independent recog-nition of antigens. GUCY2C is a cancer mucosa antigen expressed on the luminal surfaces of the intestinal mucosa in mice and humans, and universally overexpressed by colorectal tumors, suggesting its unique utility as an ACT target. T cells expressing CARs directed by a GUCY2C-specific antibody fragment recognized GUCY2C, quantified by expression of activation markers and cytokines. Further, GUCY2C CAR-T cells lysed GUCY2C-expressing, but not GUCY2C-deficient, mouse colorectal cancer cells. Moreover, GUCY2C CAR-T cells reduced tumor number and morbidity and improved survival in mice harboring GUCY2C-expressing colorectal cancer metastases. GUCY2C-directed T cell efficacy reflected CAR affinity and surface expression and was achieved without immune-mediated damage to normal tissues in syngeneic mice. These observations highlight the potential for therapeutic translation of GUCY2C-directed CAR-T cells to treat metastatic tumors, without collateral autoimmunity, in patients with metastatic colorectal cancer.
Keywords: Adoptive immunotherapy; chimeric antigen receptors; colorectal cancer; gene therapy; guanylyl cyclase C.