Abstract CT524: A phase 1, first in human (FIH) study of autologous anti-HER2 chimeric antigen receptor macrophages (CAR-M) in HER2-overexpressing solid tumors (ST)

Abstract

Abstract Background: Adoptive T cell therapies have led to remarkable advances in hematologic cancers but with less effect in ST. Actively recruited tumor associated macrophages (TAM) are abundant in the ST microenvironment (TME) and typically display immunosuppressive behavior. Macrophages engineered to be proinflammatory may be an ideal vector for adoptive ST cellular therapy. Engineered CAR-M selectively recognize and phagocytose antigen overexpressing cancer cells, reprogram TME and present neoantigens to T cells, leading to epitope spreading and immune memory. Human Epidermal Growth Factor Receptor 2 (HER2) overexpression promotes tumorigenesis in many cancers (Table 1). CT-0508 is a cell product comprised of autologous monocyte-derived proinflammatory macrophages expressing an anti-HER2 CAR. Pre-clinical studies show that CT-0508 induces targeted cancer cell phagocytosis while sparing normal cells, decreases tumor burden and prolongs survival, and was safe and effective in a semi-immunocompetent mouse model of human HER2-overexpressing ovarian cancer. Methods: This FIH Phase 1 study is evaluating safety, tolerability, cell manufacturing feasibility, trafficking, and preliminary efficacy in 18 subjects with locally advanced/unresectable or metastatic ST overexpressing HER2, with progression on available therapies, including anti-HER2 therapies. Filgrastim is used to mobilize autologous hematopoietic progenitor cells for monocyte collection by apheresis prior to CT-0508 CAR macrophage infusion. Group 1 subjects receive CT-0508 on D1, 3, & 5. Group 2 subjects will receive full dose on D1. A Safety Review Committee will review dose limiting toxicities. Pre/post-treatment biopsies and blood samples will be collected for correlative analysis of immunogenicity, trafficking (PCR, RNA scope), CT-0508 persistence in blood and tumor, target antigen engagement, TME modulation (single cell RNA sequencing), immune response (TCR sequencing) and others. Table 1. Her2 Overexpression Across Tumor Types Tumor HER2 Overexpression (%) Bladder 8–70 Salivary duct 30–40 Gastric 7–34 Ovarian 26 Breast 11–25 Salivary mucoepidermoid 17.6 Esophageal 12–14 Gallbladder 9.8–12.8 Cholangiocarcinoma 6.3–9 Colorectal 1.6–5 Cervical 2.8–3.9 Uterine 3 Testicular 2.4 Citation Format: Kim A. Reiss, Yuan Yuan, Naoto T. Ueno, Yara Abdou, Debora Barton, Ramona F. Swaby, Amy Ronczka, Daniel J. Cushing, Sascha Abramson, Thomas Condamine, Michael Klichinsky, E. Claire Dees. A phase 1, first in human (FIH) study of autologous anti-HER2 chimeric antigen receptor macrophages (CAR-M) in HER2-overexpressing solid tumors (ST) [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 CT524.