Abstract 3188: Patient-derived TAC01-HER2 TAC T cells produced in Cocoon® Platform is highly functional in models of solid tumors

Abstract

Abstract Background: The T cell antigen coupler (TAC) is a novel, proprietary chimeric receptor that facilitates the re-direction of T cells to tumor cells and activates T cells by co-opting the endogenous T cell receptor complex with the goal to elicit a safe and durable anti-tumor response. TAC01-HER2, a first-in-class TAC T product targeting HER2 (ERBB2), has entered a Phase I/II clinical trial in patients with HER2-positive solid tumors. Here, we characterized the TAC T cell phenotypes and anti-tumor activity of TAC01-HER2 manufactured using leukocytes from Phase I/II patients in nonclinical in vitro and in vivo assays. Materials and Methods: TAC T cell proliferation, activation, and phenotype of patient-derived TAC01-HER2 were assessed by flow cytometric analysis. In vitro anti-tumor cytotoxicity was assessed via a real-time microscopy-based co-culture assay, and in vivo anti-tumor activity of TAC01-HER2 was assessed in mice engrafted with established solid HER2-expressing human tumors. Results: Complex phenotype analysis showed that patient-derived TAC01-HER2 products consisted of a high percentage of memory T cells similar to products generated from healthy donors. Patient-derived products had significant proportions of CD4 and CD8 T cells, with CD4 being the predominant population in several of these. In a 5-day in vitro potency assay, patient-derived products showed effective tumor cell killing at low E:T rations (1:1 to 1:20) which was comparable to product generated from healthy donors. Similarly, intravenous administration of patient-derived TAC01-HER2 in mice carrying HER2-positive tumors xenografts led to a complete and sustained tumor clearance. Conclusion: The in vitro and in vivo data confirm the potency of patient-derived TAC01-HER2 against HER2-expressing solid tumor models. This work combined with other biomarkers may help correlate nonclinical potency with clinical outcomes. Citation Format: Ling Wang, Stacey X. Xu, Tania Benatar, Ritu R. Randhawa, Philbert Ip, Prabha Lal, Thanyashanthi Nitya-Nootan, Laura Ravensbergen, Heather MacGregor, Suzy Prosser, Sadhak Sengupta, Christopher W. Helsen, Andreas G. Bader. Patient-derived TAC01-HER2 TAC T cells produced in Cocoon® Platform is highly functional in models of solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3188.