Gética 2020

54 VI FORO DE Inmunología Traslacional e INMUNOTERAPIA DEL CÁNCER Figura 2. Figura 3. Introduction: Chimeric Antigen Receptor (CAR)-ex- pressing T (CAR-T) cells and bispecific antibodies (bsAbs), which cross-link tumor and T cells inde- pendently of their TCR specificity, are promising strate- gies to cancer immunotherapy. However, each of these strategies have its own pros and contras. Recently, our group has proposed a new strategy to treat hemato- logical malignancies, based on the endogenous secre- tion of T cell-redirecting bsAbs (STAb), which combines advantages of both CAR-T and bsAbs therapies. CAR-T cells and bsAb have shown impressive clin- ical results in hematological but not solid tumors. This is due, among other reasons, to overexpres- sion in solid tumors of PD-L1, implicated in T cell exhaustion. To overcome this limitation, it is essen- tial to develop therapies that not only redirect T lymphocytes to kill cancer cells but also neutral- ize PD-L1-mediated immune suppression. Several studies combining a tumor-specific CAR or bsAb with a blocking anti-PD-1 or anti-PD-L1 antibody CP12. Immunotherapy of solid tumors by in situ expression of T cell-engaging bispecific antibodies targeting tumor-associated antigens and PD-L1 Domínguez-Alonso, Carmen 1,2 ; Erce-Llamazares, Ainhoa 1,2 ; Díez-Alonso, Laura 1,2 ; Hangiu, Oana 1,2 ; Rubio-Pérez, Laura 1,2 ; Ramírez-Fernández, Ánge l1,2 ; Blanco, Belén 1,2 ; Álvarez-Vallina, Luis 2,3 1 Inmuno-Oncología e Inmunoterapia. Instituto de Investigación 12 de Octubre. Madrid, Spain. 2 Unidad de Inmunoterapia del Cáncer (UNICA). Servicio de Inmunología. Hospital Universitario 12 de Octubre. Madrid, Spain. 3 Immunotherapy and Cell Engineering Laboratory. Aarhus University. Aarhus, Denmark have been published, showing improved results compared to each therapy separately. Objectives: The aims of this project were to pro- duce and characterize an anti-PD-L1 x anti CD3 bsAb in a tandem single-chain Fv (scFv) format (otherwise known as a bispecific T cell-engager or BiTE), and to generate a genetic construct which allows equimolar and simultaneous expression of the anti-PD-L1 BiTE and a conventional tumor-as- sociated antigen (TAA)-targeting bispecific light T cell-engager (LiTE) (1). Methods and results: The anti-PD-L1 BiTE was secreted as soluble protein by liposome-transfect- ed HEK-293 cells. The antibody was purified from conditioned medium by IMAC chromatography, and Western-blot (WB) analysis showed a migra- tion pattern consistent with the molecular weight (MW) calculated from its amino acid sequence (57 kDa). Ability to detect antigen was studied by ELISA