Francisco J. Blanco, Miguel Ángel Morcillo, Ainhoa Erce-Llamazares, Nekane Merino, Eva M. Garrido-Martin, Luis Álvarez-Vallina, Ignacio Melero, Laura Sanz, Antonio Tapia-Galisteo, Marta Oteo, Ángel Ramírez-Fernández, Irene Ferrer, Seandean Lykke Harwood, Eduardo Romero, Belén Blanco, Manuela Zonca, Carmen Domínguez-Alonso, Oana Hangiu, Inés G. Muñoz, Maria C. Ochoa, Marta Compte, Luis Paz-Ares, Ana Belén Enguita, Daniel Nehme-Álvarez, José Luis Rodríguez-Peralto, European Commission, Ministerio de Ciencia, Innovación y Universidades (España), Ministerio de Economía y Competitividad (España), Instituto de Salud Carlos III, Fundación CRIS contra el Cáncer, Fundación Científica Asociación Española Contra el Cáncer, Compte, Marta [0000-0002-7138-9266], Harwood, Seandean Lykke [0000-0003-4654-8832], Tapia-Galisteo, Antonio [0000-0002-0507-8435], Garrido-Martin, Eva M. [0000-0002-8094-2668], Ochoa, Maria Carmen [0000-0001-9920-2144], Oteo, Marta [0000-0002-2855-3403], Merino, Nekane [0000-0003-0721-4813], Nehme-Álvarez, Daniel [0000-0001-5054-5373], Hangiu, Oana [0000-0002-2641-8531], Domínguez-Alonso, Carmen [0000-0002-0446-9629], Zonca, Manuela [0000-0003-3868-1975], Blanco, Francisco J. [0000-0003-2545-4319], Muñoz, Inés G. [0000-0001-6732-4059], Rodríguez-Peralto, J. L. [0000-0002-6578-7153], Paz-Ares, Luis [0000-0002-1947-3364], Sanz, Laura [0000-0002-3119-3218], Alvarez-Vallina, Luis [0000-0003-3053-6757], Compte, Marta, Harwood, Seandean Lykke, Tapia-Galisteo, Antonio, Garrido-Martin, Eva M., Ochoa, Maria Carmen, Oteo, Marta, Merino, Nekane, Nehme-Álvarez, Daniel, Hangiu, Oana, Domínguez-Alonso, Carmen, Zonca, Manuela, Blanco, Francisco J., Muñoz, Inés G., Rodríguez-Peralto, J. L., Paz-Ares, Luis, Sanz, Laura, and Alvarez-Vallina, Luis
32 p.-4 fig., Purpose: The induction of 4-1BB signaling by agonistic antibodies can drive the activation and proliferation of effector T cells and thereby enhance a T-cell–mediated antitumor response. Systemic administration of anti-4-1BB–agonistic IgGs, although effective preclinically, has not advanced in clinical development due to their severe hepatotoxicity., Experimental Design: Here, we generated a humanized EGFR-specific 4-1BB-agonistic trimerbody, which replaces the IgG Fc region with a human collagen homotrimerization domain. It was characterized by structural analysis and in vitro functional studies. We also assessed pharmacokinetics, antitumor efficacy, and toxicity in vivo., Results: In the presence of a T-cell receptor signal, the trimerbody provided potent T-cell costimulation that was strictly dependent on 4-1BB hyperclustering at the point of contact with a tumor antigen-displaying cell surface. It exhibits significant antitumor activity in vivo, without hepatotoxicity, in a wide range of human tumors including colorectal and breast cancer cell-derived xenografts, and non–small cell lung cancer patient-derived xenografts associated with increased tumor-infiltrating CD8+ T cells. The combination of the trimerbody with a PD-L1 blocker led to increased IFNγ secretion in vitro and resulted in tumor regression in humanized mice bearing aggressive triple-negative breast cancer., Conclusions: These results demonstrate the nontoxic broad antitumor activity of humanized Fc-free tumor-specific 4-1BB-agonistic trimerbodies and their synergy with checkpoint blockers, which may provide a way to elicit responses in most patients with cancer while avoiding Fc-mediated adverse reactions., This work was supported by grants from the European Union [IACT Project (602262), H2020-iNEXT (1676)]; the Spanish Ministry of Science, Innovation and Universities and the Spanish Ministry of Economy and Competitiveness (SAF2017-89437-P, CTQ2017-83810-R, RTC-2016-5118-1, RTC-2017-5944-1), partially supported by the European Regional Development Fund; the Carlos III Health Institute (PI16/00357), co-founded by the Plan Nacional de Investigación and the European Union; the CRIS Cancer Foundation (FCRIS-IFI-2018); and the Spanish Association Against Cancer (AECC, 19084). C. Domínguez-Alonso was supported by a predoctoral fellowship from the Spanish Ministry of Science, Innovation and Universities (PRE2018-083445). M. Zonca was supported by the Torres Quevedo Program from the Spanish Ministry of Economy and Competitiveness, co-founded by the European Social Fund (PTQ-16-08340).