Abstract 2159: Establishment of new preclinical tumor models for pancreatic neuroendocrine carcinoma.

Abstract Introduction: Pancreatic neuroendocrine carcinoma (PanNEC) is an extremely aggressive and rare malignancy with a poor prognosis. Owing to its rarity, therapeutic development has been significantly delayed, highlighting the urgent need for novel treatment strategies. Although preclinical models such as cell lines and patient-derived xenograft (PDX) models are essential tools for drug discovery, only one PanNEC cell line has been reported to date. In this study, we successfully established novel PanNEC cell lines and multiple PDX models and aimed to clarify their biological features and drug responses. Experimental procedures:Tumor tissue obtained from a PanNEC patient was sutured onto the pancreatic tail of severe combined immunodeficient (SCID) rats to generate orthotopic pancreatic PDX models. In addition to orthotopic models, subcutaneous models and peritoneal dissemination models were created. Tumor tissue and malignant ascites obtained from orthotopic PDX models were subjected to primary culture, leading to the establishment of two novel PanNEC cell lines. Drug sensitivities to etoposide, irinotecan, cisplatin, and carboplatin were assessed using the CCK-8 assay. Furthermore, cell line-derived xenograft (CDX) subcutaneous models were generated to validate in vivo tumorigenicity. Summary of the data:The engraftment rate of the orthotopic pancreatic PDX was 100% (2/2), with engraftment requiring approximately two months. Both tumor-derived and ascites-derived cell lines exhibited semi-adherent morphology. Tumor-derived cells showed planar adherent proliferation, whereas ascites-derived cells demonstrated three-dimensional spheroid-forming growth. The doubling times were 2.7 and 2.5 days, indicating strong proliferative capacity. Immunohistochemistry showed consistent expression of markers such as synaptophysin and chromogranin A across the primary tumor, PDX models, CDX models and the established cell lines. CCK-8 assays revealed growth-inhibitory effects for all four drugs without notable resistance, and the combination of etoposide and cisplatin demonstrated a synergistic effect. Conclusion: We successfully established novel PanNEC cell lines and multiple PDX models, including orthotopic, subcutaneous, and peritoneal dissemination models, as well as CDX models. These rare models provide a valuable platform for future preclinical studies and may facilitate the development of new therapeutic strategies for PanNEC. Citation Format: Takuto Yasuda, Ryota Tanaka, Daisuke Inoue, Koichi Nakanishi, Kosuke Hatta, Shigeaki Kurihara, Jun Tauchi, Sadaaki Nishimura, Masahiko Kinoshita, Kohei Nishio, Hiroji Shinkawa, Ken Kageyama, Akira Yamamoto, Takeaki Ishizawa. Establishment of new preclinical tumor models for pancreatic neuroendocrine carcinoma abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2159.