Abstract 1903: Zenocutuzumab, a HER2xHER3 bispecific antibody, is effective in cancer models with high NRG1 expression

Abstract

Abstract Neuregulin 1 (NRG1) is a ligand that binds to HER3, promotes HER2/HER3 dimerization and PI3K/AKT/mTOR signaling, and causes malignant transformation. Zenocutuzumab (Zeno, MCLA-128) is a humanized IgG1 bispecific antibody that docks on HER2, preventing heterodimerization with HER3, while also blocking NRG1 interaction with HER3, and potently inhibiting NRG1-induced HER2:HER3 proliferation and survival signaling of cancer cells. High NRG1 expression arising from autocrine signaling or gene amplification is associated with poor prognosis in certain cancers, and resistance to standard therapies. The clinical efficacy and safety of Zeno in patients with NRG1 fusion-driven cancer who were enrolled in the ongoing global multicenter eNRGy study and Early Access Program were recently presented. Treatment with Zeno led to durable responses across multiple different previously treated NRG1 fusion tumor types. Zeno utilizes the Merus Dock & Block® mechanism to inhibit HER2/HER3 dimerization and the NRG1/HER3 tumor-signaling pathway and is effective at high NRG1 concentrations. Here, we examined the efficacy of Zeno in preclinical models representing different tumor types expressing high NRG1 levels. Zeno treatment of the lung cancer cell line HCC95, which harbors an NRG1 gene amplification, effectively inhibited signaling pathways involved in the regulation of proliferation and survival, including the PI3K/AKT/mTOR pathway and inhibited cell proliferation. The anti-tumor efficacy of Zeno in vivo against a panel of 28 patient-derived xenograft (PDX) models representing different tumor types was examined. Zeno significantly inhibited tumor growth in seven high-NRG1-expressing PDX models. These results show that Zeno is effective in tumor cell killing in vitro and in vivo in high NRG1-expressing cancer models representing multiple different tumor types. Citation Format: Marie N. O'Connor, Ron C. Schackmann, Igor Odintsov, Szabolcs Fatrai, Arie B. Brinkman, Sidney Walker, Jeroen J. Lammerts van Bueren, Cecile A. Geuijen. Zenocutuzumab, a HER2xHER3 bispecific antibody, is effective in cancer models with high NRG1 expression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1903.