Abstract 1046: Developing patient-derived xenograft tumor models that recapture clinical manifestation of inflammatory breast cancer patients

Inflammatory breast cancer (IBC) is the most aggressive clinical manifestation of breast cancer (BC), with striking erythema of the overlying skin, and exhibiting features of early metastatic and treatment-refractory disease. Malignant cells and infiltrating leukocytes, e.g. tumor-associated microphages (TAMs) commonly designated "M2" macrophages, play a major part in metastasis and treatment resistance. TAMs help promote tumor growth and progression. There is a significant need for preclinical models that retain the characteristics of the original patient tumor for investigating mechanisms of IBC metastasis and for testing candidate therapies. Six samples of pleural effusion-derived tumor cells or circulating tumor cells (CTCs) from five IBC or metastatic breast cancer (MBC) patients were obtained from Northwestern Memorial Hospital. IBC cells were used for 3D tumor spheroid cultures, and for developing PDX tumor models in immunodeficient mice. Short Tandem Repeat profiling against with original patient tumor DNA was conducted to establish patient DNA identify, and to serve as a reference for authenticating derivative tumor models. The tumor genomic mutation analysis indicated the most common alterations of five IBC or MBC patients were TP53 (75%), CCND1 (75%), BRCA2 (50%), NF1 (50%), FGFR1 (50%), CDK6 (50%), EGFR (50%), MYC (50%), BRAF (50%). Examination IBC pleural effusion cellular composition indicated ~60% were tumor cells and ~40% were M2 TAMs (CD163+). In early 3D spheroid IBC culture, a symbiotic phenomenon was observed between tumor cells and attached TAMs; Anti-cancer drugs GW2580 and Pexidartinib inhibited 32% and 68% of cell proliferation, respectively, when added to spheroid cultures at 100 nanomolar. Histopathologic analysis of derivative IBC and MBC PDX revealed highly heterogeneous characteristics and metastatic features characteristic of corresponding patient tumors. Subcutaneous tumors also demonstrated metastasis to liver and lung tissue. NSG mice engrafted with original IBC pleural effusion cells or derived spheroid cultures manifested a variety of inflammatory clinical symptoms. Mice engrafted with original pleural effusion cells developed palpable tumor and manifested most IBC-characteristic including reddish and ulcerated skin lesions necessitating euthanasia within 2 months of cell engraftment. Mice engrafted with > 6 passage or Our results indicate IBC 3D spheroid cultures and PDX tumor models recapitulate clinical characteristics observed in IBC patients, and will prove useful for studying mechanisms of IBC metastasis as well as responsiveness to investigational therapies. Citation Format: Wenan Qiang, Youbin Zhang, Demirkan Gursel Gursel, Jian-Jun Wei, Charles David James, Thomas V. O9Halloran, Massimo Cristofanilli. Developing patient-derived xenograft tumor models that recapture clinical manifestation of inflammatory breast cancer patients [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 1046.