Highly Efficient Targeting of EGFR-Expressing Tumor Cells with UniCAR T Cells via Target Modules Based on Cetuximab®

Justyna Jureczek,1– 3 Anja Feldmann,3 Ralf Bergmann,3,4 Claudia Arndt,3 Nicole Berndt,3 Stefanie Koristka,3 Liliana Rodrigues Loureiro,3,5 Nicola Mitwasi,3 Anja Hoffmann,3 Alexandra Kegler,1– 3 Tabea Bartsch,3 Michael Bachmann1– 3,5,6 1German Cancer Consortium (DKTK), Dresden, Germany; 2German Cancer Research Center (DKFZ), Heidelberg, Germany; 3Department of Radioimmunology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany; 4Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary; 5National Center for Tumor Diseases (NCT), German Cancer Research Center (DKFZ), Heidelberg; Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden; Helmholtz-Zentrum Dresden - Rossendorf (HZDR), Dresden, Germany; 6Tumor Immunology, University Cancer Center (UCC), University Hospital Carl Gustav Carus Dresden, Technische Universität Dresden, Dresden, GermanyCorrespondence: Michael BachmannHelmholtz-Zentrum Dresden-Rossendorf e.V. Managing Director, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, Dresden 01328, GermanyTel +49 351 260 3170Fax +49 351 260 3232Email m.bachmann@hzdr.deIntroduction: Since epithelial growth factor receptor (EGFR) overexpression is linked to a variety of malignancies, it is an attractive target for immune therapy including chimeric antigen receptor (CAR)-engineered T cells. Unfortunately, CAR T cell therapy harbors the risk of severe, even life-threatening side effects. Adaptor CAR T cell platforms such as the previously described UniCAR system might be able to overcome these problems. In contrast to conventional CARs, UniCAR T cells are per se inert. Their redirection towards target cells occurs only in the presence of a tumor-specific target molecule (TM). TMs are bifunctional molecules being able to recognize a tumor-associated antigen and to cross-link the CAR T cell via a peptide epitope recognized by the UniCAR domain.Materials and Methods: Here, we compare αEGFR TMs: a nanobody (nb)-based αEGFR TM derived from the camelid αEGFR antibody 7C12 with a murine and humanized single-chain fragment variable (scFv) based on the clinically used antibody Cetuximab®.Results: In principle, both the nb- and scFv-based TM formats are able to redirect UniCAR T cells to eliminate EGFR-expressing tumor cells in an antigen-specific and TM-dependent manner. However, the scFv-based αEGFR TM was significantly superior to the nb-based TM especially with respect to lysis of tumor cells.Discussion: Improved efficiency of the scFv-based TM allowed the redirection of UniCAR T cells towards tumor cells expressing high as well as low EGFR levels in comparison to nb-based αEGFR TMs.Keywords: EGFR, UniCAR, CAR T cells, adaptor CARs, solid tumors, immunotherapy