A Bispecific Antibody Based on Heterodimeric Fc Demonstrates Potent Anti-Tumor Efficacy by Targeting Met and VEGFR-2 Simultaneously

摘要

Bispecific antibody (bsAb) targeting two different molecules simultaneously provide therapeutic benefits in complicated diseases. However, wild-type human IgG1 recognizes single type of target because of the homodimeric association of CH3 domains. Heterodimeric Fc designed by engineering the CH3 homodimeric interface of IgG1 serves as an attractive scaffold for the generation of bsAbs due to the favorable properties of Fc region. In this study, we present a heterodimeric Fc, generated by substituting the conserved electrostatic interactions at CH3 core interface with asymmetric hydrophobic interactions and introducing asymmetric, long-range electrostatic interactions at the rim of CH3 interface. The generated heterodimeric Fc had comparable heterodimer yield and thermal stability compared to control KiH Fc variant. The heterodimeric Fc scaffold was applied to generate a bispecific antibody targeting both Met receptor tyrosine kinase and vascular endothelial growth factor receptor 2 by fusing two different single-chain variable fragment (scFv) into the N-terminus of heterodimeric Fc. The Met x VEGFR-2 bsAb efficiently inhibited the downstream signaling of two receptors and tube formation in human endothelial cells, and demonstrated more potent anti-tumor efficacy in MKN45 human gastric cancer xenograft models than both the parent monospecific antibody alone. Taken together, based on the newly designed heterodimeric Fc-based bsAb, our results offer the therapeutic potential of bispecific antibody targeting both VEGFR-2 and Met concurrently for the treatment of human cancers.