VEGFR2-specific FnCAR effectively redirects the cytotoxic activity of T cells and YT NK cells

// Sergey V. Kulemzin 1, * , Andrey A. Gorchakov 1, 2, * , Anton N. Chikaev 1 , Valeriya V. Kuznetsova 1 , Olga Y. Volkova 1 , Daria A. Matvienko 1, 2 , Alexey V. Petukhov 3 , Andrey Y. Zaritskey 3 and Alexandr V. Taranin 1, 2 1 Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia 2 Novosibirsk State University, Novosibirsk, Russia 3 Institute of Hematology, Almazov National Medical Research Centre, St Petersburg, Russia * These authors contributed equally to this work Correspondence to: Alexandr V. Taranin, email: taranin@mcb.nsc.ru Keywords: chimeric antigen receptors; NK cells; Fn3; VEGFR2; FnCAR Received: March 06, 2017      Accepted: January 02, 2018      Published: January 09, 2018 ABSTRACT T and NK cells armed with chimeric antigen receptors (CAR) are promising tools for the specific elimination of cancer cells. In most CAR designs implemented to date, the recognition of target cells is mediated by single-chain variable fragments (scFvs) derived from murine monoclonal antibodies. This format, however, has a number of limitations, including its relatively large size and potential immunogenicity in humans. In this study, we explored the feasibility of using human fibronectin type III domains (Fn3) as the antigen recognition domain in CARs. Human Fn3 domains have lower predicted immunogenicity compared to mouse-derived sequences, and a reduced molecular weight compared to scFvs. We created a functional CAR using a VEGFR2-specific Fn3 module replacing the conventional scFv. The resulting FnCAR specifically potentiates the cytotoxic activity of human T cells and YT NK cells in the presence of VEGFR2-positive targets. These findings demonstrate that Fn3 domains can be used in CARs for antigen recognition.