Approximately 1 in 8 women will develop breast cancer in their lifetime, and many require a combination of debilitating surgery, chemotherapy or radiation for long term survival. Histologic evaluation of biomarkers such as estrogen receptor and Her2 often dictate treatment regimens. However, despite high initial response rates, relapses are common, and choosing the right therapy for each patient remains challenging. In vitro 3D models of breast cancer that maintain biologic features and more closely resemble clinical disease than 2D models are a promising option for pre-determining the best, most effective therapies for patients. Utilizing both immortalized cell lines and patient-derived xenografts (PDX) lines, we have developed a complex 3D model of breast cancer that combines cancer cells, fibroblasts, and adipocytes in a 3D matrix under perfusion culture (3D microtumors). We have examined these microtumors for metabolism as measured by redox ratio, biomarker expression, and drug response. Using multiphoton microscopy, we have been able to not only live image our 3D microtumors in a non-destructive manner, but also to develop a profile of their redox ratio based upon the autofluorescence of NADH and FAD. Tumor cells often switch from oxidative phosphorylation to aerobic glycolysis for ATP generation (Warburg effect) and previous data examining redox ratios in 2D breast cancer cells have shown that the ratio of NADH to FAD is higher in HER2+ cell lines compared to ER+ cell lines indicating that HER2+ cells utilize aerobic glycolysis more than ER+ cell lines. While we have been able to replicate that data using cell lines in 2D culture, all of our 3D microtumors have indicated a different redox ratio where triple negative breast cancers have the highest redox ratio and ER+ and HER2+ microtumors have similar but lower redox ratios. Cell line and PDX-derived microtumors were used to compare soluble factors secreted across 3D static and 3D perfusion and we have found that both 3D culture, perfusion and higher redox ratios are associated with increased cancer associated biomarker secretion. Furthermore, relative increases or decreases of biomarkers in 3D allowed for the identification of unique secretome signatures according to breast subtype, but these signatures varied between cell lines and PDX-derived microtumors. 3D Microtumors from cell lines better identified tamoxifen and cisplatin as active agents against ER+ and TNBC tumor cells as compared to 2D. Whereas drug response using PDX was not feasible due to poor adaptation to 2D conditions, we were able to assess drug response using both redox ratio and resazurin reduction using our 3D microtumors derived from PDX and have verified molecular subtype-dependent drug responses. By combining drug response profiling with redox ratio and biomarker analysis we have developed a profile of these 3D microtumors that correlates to the molecular subtype of breast cancer cells. This work demonstrates the potential utility of label-free, non-destructive MPM analysis of complex 3D microtumors for early and continuous drug response assessment. Future work is focusing on correlating drug responses to clinical response in microtumors derived from primary human breast tumors.

Citation Format: Tessa DesRochers, Stephen Shuford, Christina Mattingly, Terri Bruce, Matt Gevaert, David Kaplan, David Orr, Hal E. Crosswell. Drug response profiling, redox ratio, and biomarker analysis in an in vitro 3D tri-culture model of breast cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B201.