Abstract 3001: Multicellular structures of serous ovarian cancer nature isolated from pleural effusions are sufficient to recreate peritoneal carcinomatosis in immunosuppressed mice

High-grade serous ovarian cancer (HGSOC) is a lethal disease often diagnosed in grade III International Federation of Gynecology and Obstetrics (FIGO) upon colonization of the peritoneal cavity, or in grade IV FIGO when it colonizes the pleural cavity. When in the pleural cavity, the disease often manifests with accumulation of pleural effusions containing multicellular structures (MCS). In this work, we studied whether MCS isolated from a pleural effusion of a patient that did not respond to chemotherapy are sufficient to cause peritoneal carcinomatosis in immunosuppressed mice when implanted orthotopically. Nude mice were injected intraperitoneally with MCS isolated from the pleural effusions of a heavily treated patient. We determined the time taken for the disease to develop, the tissues targeted, presence or absence of ascites, the macroscopic and microscopic disease appearance, and the expression of standard biomarkers of HGSOC. We contrasted the histopathology of the tumors recreated in mice against that of the original tumor taken during diagnostic surgery. MCS from pleural effusions were sufficient to recreate disease in the mice, which reached their humane-endpoint seven months following MCS injection (n=3). The animals developed abundant cellular peritoneal ascites. In addition, macro and microscopic discrete disease was observed in the fat surrounding the ovaries, the omental-pancreatic area, the peritoneal wall, a lymph node, the diaphragm, and the lung. The histopathology of the disease showed infiltrating papillary architecture, areas with cells arranged in a solid pattern, and tumor nests with slit-like lumens that stained positive for mutant p53, p16, and WT1. Our results provide proof of principle that MCS isolated from pleural effusions of a HGSOC patient are sufficient to recreate peritoneal carcinomatosis in nude mice, depicting most morphological features found at postoperative diagnosis. Citation Format: Alicia A. Goyeneche, Ashwyna Sunassee, Sabrina J. Ritch, Michael Koch, Maria Bell, Zu-hua Gao, Carlos M. Telleria. Multicellular structures of serous ovarian cancer nature isolated from pleural effusions are sufficient to recreate peritoneal carcinomatosis in immunosuppressed mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3001.