Abstract P6-06-02: An in vitro microfluidic tumor platform for modeling and investigating tumor stromal interactions in inflammatory breast cancer
Authors: Gadde Manasa , Phillips Caleb , Rahal Omar , Woodward Wendy , Rylander Marissa , Yankeelov Thomas 
Published: March 2020

Abstract
Introduction: Inflammatory breast cancer (IBC) is an aggressive and rare disease with poor prognosis, accounting for 10% of breast cancer mortality [1]. A primary factor contributing to the bleak prognosis is the lack of IBC specific treatments. There are currently no IBC specific therapies due to a lack of IBC specific diagnostic and targeting markers. Efforts focused on identifying driver mutations and tumor targets have implicated tumor stroma including stromal cells such as macrophages in mediating IBC-like symptoms. This highlights the significance of understanding the interactions of tumor cells with the tumor stroma in greater detail and the knowledge would enable determination of targetable biology from these interactions which would facilitate development of IBC specific treatments and therapeutics. What is needed is a model to capture the complexity of IBC, identify critical spatial hetero-cellular interactions and target them successfully in a physiologically relevant and high-throughput manner.
Approach: To address this need, we developed a 3D IBC microfluidic platform, unique in its simultaneous integration of functional blood vessels, tumor cells, macrophages, and type I collagen whose density, stiffness, and porosity mimics cancerous breast stroma. The platform will be used to study the influence of macrophage-tumor-endothelial interactions on 2 key critical features of IBC: vascular sprouting and formation of IBC emboli surrounded by vascular sprouts.
Results: The 3D IBC microfluidic platform composed of MDA-IBC3 cells and a functional endothelial blood vessel demonstrated both vascular sprouting and emboli formation, key features of IBC tumors seen in IBC patient derived xenograft (PDX) models. Additionally, we observed vascular nesting of MDA-IBC3 emboli, recreating a characteristic IBC phenomenon observed in Mary-X PDX models. Incorporation of macrophages significantly increased the number of new vascular sprouts, sprouting rate and resulted in sprouts forming at earlier time points. Additionally, the presence of macrophages resulted in the formation of a significantly more porous collagen matrix (p&lt;0.05), increased endothelial vessel permeability (p&lt;0.05) and expression of proangiogenic factors, IL-8 and MMP9 (p&lt;0.05, p&lt;0.05) compared to platforms without macrophages. 3D platforms with macrophages also exhibited vascular nesting of MDA-IBC3 emboli but no significant differences in the number of nested emboli were detected. Finally, in 3D platforms with macrophages, we observed intravasation of MDA-IBC3 emboli which was absent in platforms without macrophages.
Conclusion: IBC is an aggressive and invasive breast cancer with a poor prognosis linked to tumor-stroma interactions. Current preclinical to study IBC consist primarily of PDX models where determining the influence of specific signaling pathways and microenvironmental stimuli on tumor progression is challenging. Here we present a novel 3D microfluidic IBC platform to study tumor stromal interactions in a controlled manner. The MDA-IBC3 breast tumor platform demonstrated both vascular sprouting and emboli formation, key features of IBC seen in PDX models and the presence of macrophages increased both angiogenic sprouting and remodeling of the collagen matrix. The stark differences in the tumor platform response associated with macrophage presence strengthens the hypothesis of tumor stroma as a key player driving the aggressive nature of IBC and reveals a potential target for IBC therapeutics.
[1] Fernandez, S.V., et al., Breast cancer research and treatment, 140(1): p. 23-33, 2013
Citation Format: Manasa Gadde, Caleb Phillips, Omar Rahal, Wendy Woodward, Marissa Rylander, Thomas Yankeelov. An in vitro microfluidic tumor platform for modeling and investigating tumor stromal interactions in inflammatory breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-06-02.