Abstract OT1-03-01: A phase 1, first in human (FIH) study of adenovirally transduced autologous macrophages engineered to contain an anti-HER2 chimeric antigen receptor (CAR) in subjects with HER2 overexpressing solid tumors
Authors: Abdou Yara George , Barton Debora , Ronczka Amy , Cushing Daniel , Klichinsky Michael , Binder Kim Reiss 
Published: March 2022

Adoptive T cell therapies have led to remarkable advances among patients with hematologic malignancies, but not in those with solid tumors. Macrophages are actively recruited into, and abundantly present in the solid tumor microenvironment (sTME). Tumor- associated macrophages typically evince immunosuppressive behavior, but when engineered to be proinflammatory, may be an ideal vector to administer adoptive cellular therapy in solid tumors. Furthermore, insertion of a CAR on the macrophages confers the ability to selectively recognize and phagocytose antigen overexpressing cancer cells. Additionally, CAR macrophages reprogram the sTME and present neoantigens to T cells, leading to epitope spreading and immune memory. Human Epidermal Growth Factor Receptor 2 (HER2) overexpression promotes tumorigenesis and is seen in many cancers, including but not limited to breast and gastroesophageal cancers (Table 1). CT-0508 is a cell product comprised of autologous monocyte-derived pro-inflammatory macrophages expressing an anti-HER2 CAR. Pre-clinical studies have shown that CT-0508 induced targeted cancer cell phagocytosis while sparing normal cells, decreasing tumor burden and prolonging survival in relevant models. CT-0508 cells were safe and effective in a semi-immunocompetent mouse model of human HER2 overexpressing ovarian cancer. This is a FIH Phase 1 study to evaluate safety, tolerability, cell manufacturing feasibility, trafficking, and preliminary evidence of efficacy of investigational product CT-0508 in approximately 18 subjects with locally advanced (unresectable) or metastatic solid tumors overexpressing HER2, who have failed available therapies including anti-HER2 therapies where indicated.Filgrastim is being used to mobilize autologous hematopoietic progenitor cells for monocyte collection by apheresis. The CT-0508 CAR macrophage product is manufactured, prepared and cryopreserved from mobilized peripheral blood monocytes. The study is enrolling Group 1 subjects, who receive CT-0508 infusion split over D1, 3 and 5. Subjects will be continually assessed for acute and cumulative toxicity. Dose limiting toxicities will be observed and addressed by a Safety Review Committee. Group 2 subjects will follow, and will receive the full CT-0508 infusion on D1. Pre and post treatment biopsies and blood samples will be collected to investigate correlates of safety (immunogenicity), trafficking (PCR, RNA scope), CT-0508 persistence in blood and in the tumor, target antigen engagement, TME modulation (single cell RNA sequencing), immune response (TCR sequencing) and others. Clinical trial registry number: NCT04660929

Table 1.HER2 Positivity Frequencies Across Tumor TypesTumor typeHER2 positivity (%)ReferenceBladder cancer8-70Gandour-Edwards et al, 2002;Caner et al, 2008;Laé et al, 2010; Fleischmann et al, 2011;Charfi et al, 2013;Yan et al, 2015Breast cancer11.0-25.0Varga et al, 2013;Stenehjem et al, 2014Cervical cancer2.8-3.9Chavez-Blanco et al, 2004;Yan et al, 2015Colorectal cancer1.6-5.0Schuell et al, 2006;Ingold Heppner et al, 2014;Seo et al, 2014Esophageal cancer12.0-14.0König et al, 2013;Yoon et al, 2013;Wang et al, 2014Extrahepatic Cholangiocarcinoma6.3-9.0Yoshikawa et al, 2008;Yan et al, 2015Gallbladder cancer9.8-12.8Roa et al, 2014;Yan et al, 2015Gastric adenocarcinoma7.0-34.0Rüschoff et al, 2012;Hofmann et al, 2008Ovarian cancer26Slamon et al, 1989Salivary mucoepidermoid carcinomas17.6Glisson et al, 2004Salivary duct carcinoma30-40Skálová et al, 2003; Cornolti et al, 2007; Nardi et al, 2013Testicular cancer2.4Yan et al, 2015Uterine cancer3.0Yan et al, 2015

Citation Format: Yara George Abdou, Debora Barton, Amy Ronczka, Daniel Cushing, Michael Klichinsky, Kim Reiss Binder. A phase 1, first in human (FIH) study of adenovirally transduced autologous macrophages engineered to contain an anti-HER2 chimeric antigen receptor (CAR) in subjects with HER2 overexpressing solid tumors [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT1-03-01.