Abstract 5609: ERY974, a novel T cell-redirecting bispecific antibody targeting glypican-3, shows antitumor activity in gastric cancer patient-derived xenograft models with varying glypican-3 expression
Authors: Yumiko Azuma , Sano Yuji , Tsunenari Toshiaki , Kinoshita Yasuko , Miyazaki Yoko , Shinozuka Junko , Fujii Etsuko , Kato Atsuhiko , Ishiguro Takahiro , Kishishita Shohei , Nezu Junichi , Kawabe Yoshiki , Endo Mika 
Published: August 2018

Abstract
Background: ERY974 is a humanized IgG4 bispecific T cell-redirecting antibody (TRAB) currently in a Phase 1 clinical trial (NCT02748837) in patients with solid tumors that are glypican-3 (GPC3)-positive. ERY974 consists of a common light chain but has two different heavy chains that each recognize a different protein, GPC3 or CD3. ERY974 simultaneously binds to GPC3 on the cancer cell surface and to CD3 on the T cell surface to induce cellular cytotoxicity mediated by the potent effector function of T cells. The Fc portion of ERY974 is modified to eliminate FcγR binding and prevent GPC3-independent Fc-mediated effector function. However, binding to FcRn, an important factor in the PK profile of IgG, is maintained. ERY974 shows strong antitumor activity against gastric, lung, ovarian, head & neck, hepatic, and esophageal cancer-derived tumors in a non-obese diabetic/severe combined immunodeficiency (NOD-SCID) mouse model injected with human T cells. In a cohort expansion of the Phase 1 trial, the activity of ERY974 will be examined in gastric cancer; however, individual clinical samples do not show uniform expression levels of GPC3 in tumor lesions, reflecting the heterogenous and complex structure of patients' tumors. To predict the potential efficacy of ERY974 in gastric cancer patients, we examined whether ERY974 alone or in combination with chemotherapy, could show substantial activity against heterogenous tumors with different GPC3 expression profiles using patient-derived xenografts (PDX) of gastric cancer.
Method & results: We evaluated the antitumor effect of ERY974 in PDX gastric cancer tumors that have high, moderate, or low expression levels of GPC3 in a NOD-SCID mouse model injected with human T cells that were expanded in vitro using CD3/CD28 beads. The expression of GPC3 was evaluated by immunohistochemistry and quantitative RT-PCR. The efficacy of ERY974 monotherapy seemed to correlate with the GPC3 expression levels in each PDX tumor. The combination of ERY974 and chemotherapy, such as paclitaxcel, cisplatin or capecitabine, showed increased antitumor activity compared with ERY974 or chemotherapy alone.
Conclusion: These preclinical data support the possibility that ERY974 alone or in combination with chemotherapy will demonstrate activity in patients with gastric cancer, and the GPC3 expression profile might be a useful predictive biomarker of ERY974 efficacy for patient selection.
Citation Format: Azuma Yumiko, Yuji Sano, Toshiaki Tsunenari, Yasuko Kinoshita, Yoko Miyazaki, Junko Shinozuka, Etsuko Fujii, Atsuhiko Kato, Takahiro Ishiguro, Shohei Kishishita, Junichi Nezu, Yoshiki Kawabe, Mika Endo. ERY974, a novel T cell-redirecting bispecific antibody targeting glypican-3, shows antitumor activity in gastric cancer patient-derived xenograft models with varying glypican-3 expression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5609.