Abstract CT241: ENVOY-001: A phase 1, multicenter, open-label study of SQZ-AAC-HPV as monotherapy and in combination with immune checkpoint inhibitors in HLA-A*02+ patients with HPV16+ recurrent, locally advanced, or metastatic solid tumors

Abstract Background: AAC-HPV consists of autologous RBCs engineered using Cell Squeeze® technology to deliver synthetic long peptides (SLP) of HPV16 E6, E7 and the adjuvant, poly I:C. After intravenous (IV) administration, the AACs are designed to be phagocytosed by endogenous antigen presenting cells (APCs) and the E6 and E7 antigens presented on the APC’s major histocompatibility complexes (MHCs). The concurrent delivery of antigen and adjuvant to the APCs is designed to elicit a potent antitumor T cell response to drive HPV16+ tumor killing. Preclinical experiments demonstrated that post IV administration of mouse AAC-HPV in a HPV16 E7-expressing TC-1 mouse model, E7 specific CD8+ T cells are recruited to the tumor, inhibiting tumor growth, prolonging survival, and forming immunological memory. Murine AAC-HPV treatment was also shown to be synergistic with cisplatin combinations. In vitro studies with human volunteer derived SQZ-AAC-HPV demonstrated to be endocytosed by dendritic cells and drive IFN-gamma production by T cell clones specific to human E7. The Phase 1/2 study’s biomarker program investigates whether pharmacodynamic effects observed in nonclinical studies correlate with potential clinical benefit. Immunogenic and pharmacodynamic endpoints include quantification and characterization of TILs and tumor microenvironment, changes in numbers and functions of circulating blood cells. In addition, cytokine responses and cell-free HPV16 DNA will be measured. Methods: ENVOY-001 (NCT04892043) is open for enrollment to HLA A*02+ patients with HPV16+ recurrent, locally advanced, or metastatic solid tumors and includes escalation cohorts for monotherapy and in combination with anti-PD-1 and anti-CTLA-4 checkpoint inhibitors. The study is divided in two parts, the first will assess the safety in monotherapy dose-escalation following a Bayesian Optimal Interval approach. The second part of the study will assess the safety of SQZ-AAC-HPV when combined with nivolumab 360 mg q3w and/or ipilimumab 3 mg/kg q3w x4 or 1 mg/kg q6w when combined with nivolumab. The cycle length is 3 weeks, and patients will receive SQZ-AAC-HPV for up to 1 year or until available autologous drug product is exhausted. Eligible patients including but not limited to anal, cervical and head and neck tumors will undergo a 200 mL whole blood collection at the study site. The manufacturing process takes less than 24 hours to produce multiple cryopreserve patient doses and this therapy does not necessitate pre-conditioning. The vein-to-vein time for the 1st administration is approximately one week. Patients must have a lesion that can be biopsied with acceptable clinical risk and agree to have a fresh biopsy at Screening and on study. A Data Monitoring Committee is in place. No formal statistical hypothesis testing will be performed. Results: N/A Conclusions: N/A Citation Format: Victoria Villaflor, Rajwanth Veluswamy, Elena Garralda, Richard Maziarz, Emese Zsiros, Anthony Shields, Mariano Ponz-Sarvise, Martijn Lolkema, Mehdi Brahmi, Julia Jennings, Nathan Miselis, Lindsay Moore, Katarina Blagovic, Rui-Ru Ji, Scott Loughhead, Ricardo Zwirtes, Sandip Patel. ENVOY-001: A phase 1, multicenter, open-label study of SQZ-AAC-HPV as monotherapy and in combination with immune checkpoint inhibitors in HLA-A*02+ patients with HPV16+ recurrent, locally advanced, or metastatic solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT241.