Gética 2020

56 VI FORO DE Inmunología Traslacional e INMUNOTERAPIA DEL CÁNCER Introduction: The secretion of T cell-redirecting bispecific antibodies (bsAbs) by genetically mod- ified T lymphocytes (STAb-T cells) is an emerging approach that combines aspects of antibody and cell-based therapies, allowing redirection of T cell activity towards cancer cells via targeting of tu- mor-associated antigens (TAA), by soluble bispecific T cell-engager (BiTE) antibodies. The STAb-T strate- gy present several advantages over current T cell re- directing strategies for cancer immunotherapy such as active trafficking to tumor sites, long lifespan and constant release of bsAbs. Here, we designed and characterized an anti-TAA × anti-CD3 bispecific tandem single-chain fragment variable (scFv) anti- body ([scFv] 2 or BiTE), which recognizes the carci- noembryonic antigen, highly expressed in cancers of diverse origins, especially carcinomas. Methods: HEK293T cells were transfected with the anti-CEA × anti-CD3 BiTE-encoding plasmid and the ex- pression level, binding and activation properties char- acterized by western blot , ELISA and FACS. Then we constructed a BiTE-encoding lentiviral vector and lenti- viral particles produced by cotransfection of HEK293T cells through calcium phosphate precipitation. The ti- ter was determined by p24 ELISA and qRT-PCR. Human primary T cells were transduced at different multiplic- ity of infection (MOI), and the cytotoxic activity eval- uated in conventional 2D cultures and 3D cell-based organoids with CEA- and CEA+ cancer cells. Results: We successfully constructed a lentiviral vector encoding a CEA-specific BiTE, and demon- strated that primary human T cells can be efficiently transduced to secreted high levels of functional an- tibodies. The functional characterization in vitro re- vealed that secreted BITE was able to bind, induce T cell activation and specific T cell cytotoxicity against CEA-positive tumor cells in vitro . Conclusions: The endogenous secretion of CEA-specific BiTEs, by engineered human T lympho- cytes, represents a promising alternative to improve the antitumor activity of immunotherapeutic strate- gies in solid tumors. Financial support: Ministerio de Ciencia, Innovación y Universidades and Asociación Española Contra el Cáncer. CP14. Genetically engineered human T cells secreting carcinoembryonic antigen (CEA)-specific T cell-engagers induce specific lysis of CEA-positive tumor cells Nehme-Álvarez, Daniel 1,2 ; Jiménez-Reinoso, Anäis 1,2 ; Domínguez-Alonso, Carmen 1,2 ; Ramírez-Fernández, Ángel1 ,2 ; Compte, Marta 3 ; Blanco, Belén 1,2 ; Álvarez-Vallina, Luis 1,2 1 Unidad de Inmunoterapia del Cáncer (UNICA). Servicio de Inmunología. Hospital Universitario 12 de Octubre. Madrid. 2 Grupo de In- muno-Oncología e Inmunoterapia. Instituto de Investigación 12 de Octubre (i+12). Madrid. 3 Unidad de Inmunología Molecular. Hospital Universitario Puerta de Hierro Majadahonda. Majadahonda, Madrid vated primary mouse T cells cultured in presence of plastic immobilized purified human-EGFR and 4-1BB agonists. Conclusions: The small tumour-targeted 4-1BB agonist LiTCO was monomeric in solution, exhibit- ed excellent antigen binding capacity and demon- strated potent in vitro costimulatory capacity in the presence of human-EGFR. These results promote the use of smaller tu- mour-targeted 4-1BB agonists for safe and effec- tive costimulatory strategies in cancer immuno- therapy. CP15. T cell-redirecting strategy to ‘stab’ hematological tumors: beyond cars and bispecific antibodies Blanco Durango, Belén 1 ; Ramírez Fernández, Ángel 2 ; Argemí Muntadas, Lidia 3 ; Aguilar Sopeña, Óscar 4 ; Marzal Martí, Berta 5 ; Compte Grau, Marta 6 ; Nehme Álvarez, Daniel 7 ; Domínguez Alonso, Carmen 8 ; Roda Navarro, Pedro 9 ; Juan Otero, Manel 10 ; Álvarez Vallina, Luis 11 1 Instituto de Investigación. Unidad de Inmunoterapia del Cáncer (UNICA). Servicio de Inmunología. Grupo de Inmuno-Oncología e Inmunoterapia. Instituto de Investigación 12 de Octubre (i+12). Hospital Universitario 12 de Octubre. Madrid, Spain. 2 Unidad de Inmunoterapia del Cáncer (UNICA). Servicio de Inmunología. Hospital Universitario 12 de Octubre. Madrid, Spain. 3 Immunotherapy