Bispecific antibody simultaneously targeting AGR2 and PD1 mediates cytotoxic T-cell-induced antitumor response in AGR2-dependent manner and inhibits AGR2-induced PDL1 upregulation.

AGR2 is a pro-oncogenic protein overexpressed in multiple cancer types, and it promotes tumor progression. Therefore, it is regarded as a promising therapeutic target for cancer. We reported the development and antitumor mechanism of AGR2-specific monoclonal antibody 18A4. To elicit AGR2-guided synergistic antitumor response by redirecting cytotoxic T-cells, we developed first T-cell-engaging bispecific antibody (BsAb) targeting AGR2 and PD1 simultaneously. This novel BsAb efficiently targets AGR2-rich solid tumors. In this study, we elucidated the antitumor mechanisms of AGR2xPD1 BsAb in vitro and in vivo. Higher attachment of T-cells and T-cell-mediated cytotoxicity were seen in cancer cells in BsAb-treated co-culture group. BsAb enhanced T-cell activation when co-cultured with target cells, and the BsAb recruited T-cells to the AGR2-overexpressing cancer cells and induced T-cells to highly express cytolytic proteins. AGR2xPD1 BsAb enhanced co-localization of AGR2 and PD1 in AGR2-overexpressing tumor sites and mediated higher attachment and infiltration of CD3 + CD8 + cytotoxic T-cells into tumor microenvironment in mice. Additionally, AGR2xPD1 BsAb inhibited AGR2-induced angiogenesis and tumor growth. Furthermore, we demonstrate that AGR2 induced PDL1 upregulation through EGFR signaling pathway and inhibited by AGR2xPD1 BsAb. Our study reveals AGR2xPD1 BsAb could be a potential therapeutic agent for targeting AGR2-overexpressing solid tumors.