Evaluation of chimeric antigen receptor of humanized rabbit-derived T cell receptor-like antibody.

T-cell receptor (TCR)-like Abs that specifically recognize antigenic peptides presented on MHC molecules have been developed for next-generation cancer immunotherapy. Recently, we reported a rapid and efficient method to generate TCR-like Abs using a rabbit system. We humanized previously generated rabbit-derived TCR-like Abs reacting Epstein-Barr virus peptide (BRLF1p, TYPVLEEMF) in the context of HLA-A24 molecules, produced chimeric antigen receptor (CAR)-T cells, and evaluated their antitumor effects using in vitro and in vivo tumor models. Humanization of the rabbit-derived TCR-like Abs using the complementarity-determining region grafting technology maintained their specificity and affinity. We prepared a second-generation CAR using single-chain variable fragment of the humanized TCR-like Abs and then transduced them into human T cells. The CAR-T cells specifically recognized BRLF1p/MHC molecules and lysed the target cells in an antigen-specific manner in vitro. They also demonstrated antitumor activity in a mouse xenograft model. We report the generation of CAR-T cells using humanized rabbit-derived TCR-like Abs. Together with our established and efficient generation procedure for TCR-like Abs using rabbits, our platform for the clinical application of humanized rabbit-derived TCR-like Abs to CAR-T cells will help improve next-generation cancer immunotherapy.