Design Principles of an Engineered Metastatic Niche for Monitoring of Cancer Progression.

Across many types of cancer, metastatic disease is associated with a substantial decrease in 5-year survival rates relative to only a localized primary tumor. Many patients self-report metastatic disease due to disruption of normal organ or tissue function, and earlier detection could enable treatment with a lower burden of disease. We have previously reported a subcutaneous biomaterial implant for early detection by serving as an engineered metastatic niche, which has been reported to recruit tumor cells before colonization of solid organs. In this report, we investigated the design principles of the scaffold and defined the conditions for use in disease detection. Using the metastatic 4T1 triple-negative breast cancer model, we identified that a porous structure was essential to capture tumor and immune cells. Scaffolds of multiple diameters were investigated for their ability to serve as a metastatic niche, with a porous scaffold with a diameter as small as 2 mm identifying disease accurately. Additionally, scaffolds that had been in vivo for 1-5 weeks were able to identify disease accurately. Finally, the sensitivity of the scaffold relative to liquid biopsies was analyzed, with scaffolds accurately detecting disease at earlier time points than liquid biopsy. Collectively, these studies inform the design principles and use conditions for porous scaffolds to detect metastatic disease.