Abstract 7281: Targeting the YAP/TAZ-TEAD pathway with TEAD inhibitors synergizes with chemotherapy and blocks diffuse gastric cancer progression

Abstract Introduction: Diffuse gastric cancer (DGC) accounts for one third of gastric cancers and is associated with poor differentiation, discohesive growth, chemoresistance, and worse survival compared to intestinal-type tumors. DGC is typically genomically stable, and there are no approved DGC-targeted therapies. Recent studies have identified a potential tumor-promoting role for Yes-associated protein 1 and transcriptional coactivator with PDZ-binding motif (YAP/TAZ), which interact with TEAD transcription factors to regulate gene expression. Therefore, we evaluated the activity and mechanism of TEAD inhibitors in DGC preclinical models. Methods: Gastric cancer patient-derived organoids (PDOs) and cell lines were treated with TEAD inhibitors (K-975, VT103, VT104, VT107) and/or 5-fluorouracil (5-FU) for in vitro assays evaluating cell proliferation or invasion. Additional experiments were conducted to test the in vivo activity of TEAD inhibitors or shRNA-mediated knockdown of YAP in subcutaneous xenograft, orthotopic xenograft, and lung metastasis models using a genetically engineered mouse model of gastric cancer driven by oncogenic KrasG12D and loss of Trp53/Cdh1. Results: TEAD inhibitors K-975, VT103, VT104, and VT107 reduced proliferation, colony formation, and invasion in DGC cell lines and PDOs. We observed no effect of TEAD inhibitors on the viability of normal gastric organoids. Combining the TEAD1-selective inhibitor VT103 with 5-FU chemotherapy resulted in further reduction of DGC PDO viability relative to monotherapy, including in a PDO derived from a patient with locally advanced DGC that demonstrated intrinsic resistance to neoadjuvant chemotherapy. In flank tumors and orthotopic models, inhibition of the YAP/TAZ-TEAD pathway using YAP shRNA and VT103, either alone or in combination with 5-FU, abrogated primary tumor formation, with the strongest inhibition observed with combination treatment. Loss of YAP or VT103 treatment also significantly reduced lung metastasis after tail vein injection of mouse gastric cancer cells. We hypothesized that TEAD inhibition blocks an epithelial-to-mesenchymal transition (EMT) program and generation of cancer stem-like cells (CSCs). Consistent with this hypothesis, TEAD1 inhibition with VT103 or YAP knockdown reduced expression of the CSC marker CD44 in vitro and decreased expression of CD44 and the EMT marker Slug in tumor xenografts. Conclusions: The YAP/TAZ-TEAD pathway is an important driver of gastric cancer growth and metastasis, particularly in DGC where it may promote EMT and cancer stemness. TEAD inhibition reduces gastric cancer growth and invasion in vitro and in vivo in preclinical models and demonstrates synergistic activity with 5-FU chemotherapy. These results suggest a potential role for evaluating the efficacy of TEAD inhibitors in patients with DGC. Citation Format: Anastasiia Bulakhova, Jin Sun Cho, Jack T. Rifkin, Jaewon Kim, Thomas J. Ryan, Tracy T. Tang, Ryan H. Moy. Targeting the YAP/TAZ-TEAD pathway with TEAD inhibitors synergizes with chemotherapy and blocks diffuse gastric cancer progression 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 (6Suppl): Abstract nr 7281.