An Fc-free EGFR-specific 4-1BB-agonistic Trimerbody Displays Broad Antitumor Activity in Humanized Murine Cancer Models without Toxicity
Marta Compte, Seandean L Harwood, Ainhoa Erce-Llamazares, Antonio Tapia-Galisteo, Eduardo Romero, Irene Ferrer, Eva M Garrido-Martin, Ana B Enguita, Maria C Ochoa, Belén Blanco, Marta Oteo, Nekane Merino, Daniel Nehme-Álvarez, Oana Hangiu, Carmen Domínguez-Alonso, Manuela Zonca, Angel Ramírez-Fernández, Francisco J Blanco, Miguel A Morcillo, Ines G Muñoz, Ignacio Melero, José L Rodriguez-Peralto, Luis Paz-Ares, Laura Sanz, Luis Alvarez-Vallina
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.
CITATION Clin Cancer Res. 2021 Mar 30. doi: 10.1158/1078-0432.CCR-20-4625. Online ahead of print.