Engineered T Cells Targeting E7 Mediate Regression of Human Papillomavirus Cancers in a Murine Model.

e15048 Background: T-cell receptor (TCR) gene-engineered T cell therapy is a promising cancer treatment strategy. Its successful development for epithelial cancers may depend on the identification of high-avidity TCRs directed against tumor-restricted target antigens. The human papillomavirus (HPV) E7 antigen is constitutively expressed by HPV+ cancers but not by healthy tissues. Here, we report the discovery and preclinical testing of a TCR that targets HPV-16 E7. Methods: Cervix-infiltrating T-cells from women with cervical intraepithelial neoplasia were screened for reactivity against HPV-16 E6 and E7. A T cell with HLA-A*02:01-restricted specificity for E711-19 was identified, and the TCR sequence was determined. Expression of the this TCR was optimized by TCR constant region modifications. Gene-engineered T cells expressing the E7 TCR (E7 T cells) were characterized for tumor cell targeting, functional avidity, cytokine production, cytolytic function, and cross reactivity. In vivo anti-tumor activity was assessed in a murine model of established, subcutaneous human cancer xenografts. Results: E7 T cells demonstrated recognition of cervical cancer and oropharyngeal cancer tumor cell lines in cytokine production and cytolysis assays. E7 T cells displayed recognition of cognate peptide at concentrations as low as 10 picomoles, which indicated high-avidity. Consistent with this finding, the E7 TCR showed function in CD4 T cells, which lack a CD8 coreceptor. Alanine scanning of the target peptide revealed positions 4, 5, 6, and 7 to provide the major contribution to recognition by E7 T cells. Cross-reactivity assays did not detect E7 T cell targeting of human peptides with potential HLA-A*02:01 anchor resides that shared residues at positions 4, 5, 6, and 7 with E711-19. Finally, E7 T cells mediated regression of established human xenograft cervical cancer tumors in an immunodeficient mouse model. Anti-tumor activity was increased in some conditions by the concomitant administration of systemic interleukin-2. Conclusions: These preclinical findings support a clinical trial of E7 T cells for the treatment of patients with metastatic HPV-16+ cancers that is now active (NCT02858310).