Sparse-spectral microendoscopy for real-time visualization of tumor cell phenotype and microenvironment spatial heterogeneity in vivo

Cancer heterogeneity and its transformation with time propels treatment resistance and confounds patient outcomes. The inability to monitor in vivo the low abundance, heterocellular phenotypes that resist treatment and ultimately lead to patient death limits the ability to design precision therapies. Here we overcome limitations in multiplexed fluorescence phenotyping to introduce real-time, cellular resolution visualization of tumor heterogeneity in vivo. This method was performed to simultaneously map for the first time 5 individual biomarkers of stemness, proliferation, metabolism, leukocytes and angiogenesis deep within the peritoneal cavities of micrometastatic cancer mouse models at 17 frames per second (fps). The newly developed imaging system revealed distinct cancer cell phenotype-immune cell spatial correlations and clearly visualized the dynamic spatial response of resistant cancer cell niches following treatment. Furthermore, wide-field datasets were generated to facilitate derivation of a mathematical framework for quantifying biomarker spatial variation and thereby overcoming the area restrictions of conventional tumor biopsy. These results pave the way for real-time identification of cancer cell phenotypes in a clinical setting, on which optimized treatment regimens can be based for personalized treatment and precision therapy, e.g., tumor margin determination during surgical resection. Additionally, this modality can be used to obtain more fundamental insights into tumor heterogeneity and how treatments affect the molecular and cellular responses of patient-specific disease. ### Competing Interest Statement The authors have declared no competing interest.