Abstract 6343: 7E1, a novel blocking antibody targeting human anti-Müllerian-hormone-receptor II (AMHRII), elicits potent anti-tumor activity in vivo

Abstract

Abstract Anti-Müllerian hormone (AMH), is a TGF-β family autocrine hormone and cognate ligand for the type II AMH receptor (AMHR2). AMH signaling through AMHR2 plays an important role in fetal sexual development by inducing Müllerian duct regression in males. AMHR2 is aberrantly expressed in various human malignancies, including colon, testis, gastric, and ovarian cancers. Functionally, AMH has complex effects on cell cycle regulation; at physiological concentrations it promotes survival and chemoresistance of cell lines, whereas at supraphysiological concentrations it inhibits tumor cell viability. Like other TGF-β family members, binding of its target receptor effects changes in gene expression through activation of intracellular SMAD, NF-κB, and Akt signaling. We developed a fully human anti-AMHR2 monoclonal antibody, 7E1, from RenMab™ mice, which contain the full human immunoglobulin variable domain. 7E1 was found to contain a distinct binding epitope associated with efficient inhibition of AMH binding and signaling. 7E1 also displayed a better ADCC effect than the reference AMHR2 antibody. The in vivo half-life of 7E1 in AMHR2- and FcRn-humanized mice exceeded the reference antibody as well and is in a desirable range from a development perspective. To evaluate the safety and efficacy of 7E1 in vivo, we established syngeneic murine tumor models in AMHR2-humanized mice. We found that 7E1 monotherapy significantly inhibited tumor growth in a dose-dependent manner. Moreover, 7E1 was well tolerated in mice, and no adverse effects were observed even at extremely high doses (e.g. 100 mg/kg). Taken together, these data demonstrate that 7E1 is a novel anti-human AMHR2 blocking antibody with desirable pharmacokinetic and pharmacodynamic properties. 7E1 may potentially find broad application for a range of cancer indications in which AMH signaling is implicated. Citation Format: Yongfei Yang, Huilin Li, Hao Li, Yue Yan, Jianhui Li, Qingcong Lin, Huijun Yin, Xiangshan Zhou, Miao Zhang, Kunbao Wu, Leqiao Sun, Shan Zhong. 7E1, a novel blocking antibody targeting human anti-Müllerian-hormone-receptor II (AMHRII), elicits potent anti-tumor activity in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6343.