Spatial frequency domain imaging for monitoring immune-mediated chemotherapy treatment response and resistance in a murine breast cancer model

Spatial Frequency Domain Imaging (SFDI) can provide longitudinal, label-free, and widefield hemodynamic and scattering measurements of murine tumors in vivo. Our previous work has shown that the reduced scattering coefficient (μ's) at 800 nm, as well as the wavelength dependence of scattering, both have prognostic value in tracking apoptosis and proliferation during treatment with anti-cancer therapies. However, there is limited work in validating these optical biomarkers in clinically relevant tumor models that manifest specific treatment resistance mechanisms that mimic the clinical setting. It was recently demonstrated that metronomic dosing of cyclophosphamide induces a strong anti-tumor immune response and tumor volume reduction in the E0771 murine breast cancer model. This immune activation mechanism can be blocked with an IFNAR-1 antibody, leading to treatment resistance. Here we present a longitudinal study utilizing SFDI to monitor this paired responsive-resistant model for up to 30 days of drug treatment. Mice receiving the immune modulatory metronomic cyclophosphamide schedule had a significant increase in tumor optical scattering compared to mice receiving cyclophosphamide in combination with the IFNAR-1 antibody (9% increase vs 10% decrease on day 5 of treatment, p < 0.001). The magnitude of these differences increased throughout the duration of treatment. Additionally, scattering changes on day 4 of treatment could discriminate responsive versus resistant tumors with an accuracy of 78%, while tumor volume had an accuracy of only 52%. These results validate optical scattering as a promising prognostic biomarker that can discriminate between treatment responsive and resistant tumor models.1830878 - U.S. National Science Foundation; W81XWH-15-1-0070 - U.S. Department of DefensePublished versio

Diffuse optical spectroscopic imaging reveals distinct early breast tumor hemodynamic responses to metronomic and maximum tolerated dose regimens.

BACKGROUND:Breast cancer patients with early-stage disease are increasingly administered neoadjuvant chemotherapy (NAC) to downstage their tumors prior to surgery. In this setting, approximately 31% of patients fail to respond to therapy. This demonstrates the need for techniques capable of providing personalized feedback about treatment response at the earliest stages of therapy to identify patients likely to benefit from changing treatment. Diffuse optical spectroscopic imaging (DOSI) has emerged as a promising functional imaging technique for NAC monitoring. DOSI uses non-ionizing near-infrared light to provide non-invasive measures of absolute concentrations of tissue chromophores such as oxyhemoglobin. In 2011, we reported a new DOSI prognostic marker, oxyhemoglobin flare: a transient increase in oxyhemoglobin capable of discriminating NAC responders within the first day of treatment. In this follow-up study, DOSI was used to confirm the presence of the flare as well as to investigate whether DOSI markers of NAC response are regimen dependent. METHODS:This dual-center study examined 54 breast tumors receiving NAC measured with DOSI before therapy and the first week following chemotherapy administration. Patients were treated with either a standard of care maximum tolerated dose (MTD) regimen or an investigational metronomic (MET) regimen. Changes in tumor chromophores were tracked throughout the first week and compared to pathologic response and treatment regimen at specific days utilizing generalized estimating equations (GEE). RESULTS:Within patients receiving MTD therapy, the oxyhemoglobin flare was confirmed as a prognostic DOSI marker for response appearing as soon as day 1 with post hoc GEE analysis demonstrating a difference of 48.77% between responders and non-responders (p &lt; 0.0001). Flare was not observed in patients receiving MET therapy. Within all responding patients, the specific treatment was a significant predictor of day 1 changes in oxyhemoglobin, showing a difference of 39.45% (p = 0.0010) between patients receiving MTD and MET regimens. CONCLUSIONS:DOSI optical biomarkers are differentially sensitive to MTD and MET regimens at early timepoints suggesting the specific treatment regimen should be considered in future DOSI studies. Additionally, DOSI may help to identify regimen-specific responses in a more personalized manner, potentially providing critical feedback necessary to implement adaptive changes to the treatment strategy

Optical imaging markers of breast cancer treatment response and resistance

Breast cancer is currently projected to affect 1 in 8 women in the US over the course of their lifetime with more than 40,000 deaths in 2022. While there has been significant improvement in patient outcomes, the ongoing challenge of highly heterogeneous breast cancer responses to therapeutics, combined with the increasing array of agents and dosing regimens, highlights the importance of tools that can assist oncologists in monitoring and adapting regimens to improve outcomes. Non-invasive imaging modalities can provide valuable prognostic feedback by longitudinally tracking the functional and metabolic characteristic of tumors. This work focuses on a platform of three imaging modalities to investigate breast cancer response and progression in different models of different length scales from humans to mice to 3D spheroids. This dissertation will highlight two Diffuse Optical Imaging (DOI) techniques: Diffuse Optical Spectroscopic Imaging (DOSI) and Spatial Frequency Domain Imaging (SFDI) and a microscopy technique: Fluorescence Lifetime Imaging Microscopy (FLIM). The preclinical setting, and in particular, in vitro models provide the unique advantage of controlling for biological heterogeneity compared to the clinical setting. In this setting, FLIM can measure the autofluorescence of key enzymatic metabolites and quantify levels of oxidative phosphorylation (OXPHOS) compared to glycolysis. A preliminary study demonstrated that FLIM could discriminate between non-invasive vs invasive breast cancer spheroids embedded in collagen and the metabolic profile was modulated by the density of the collagen. DOI techniques utilize near-infrared light to probe tissue and can quantify the optical absorption and scattering of tissue. These optical properties can be used to determine hemodynamic and cellular growth information about tissue and tumors. SFDI can provide widefield optical properties of tumors with a penetration depth of several millimeters making it the ideal imaging modality for tracking murine breast tumors. A major advantage of utilizing a murine breast cancer model is being able to study tumors in a living organism while controlling for both subject and tumor diversity. A study was conducted that confirmed SFDI derived optical scattering served as a prognostic biomarker to discriminate between a paired immunoresponsive and immunoresistant murine breast cancer model. Finally, DOSI is a clinical instrument that can provide point optical properties with a depth sensitivity of a few centimeters making this the ideal instrument for monitoring breast tumors in breast cancer patients. A large, multi-center clinical trial demonstrated that a large tumor oxyhemoglobin increase is a strong prognostic biomarker of treatment response as soon as the first day after treatment onset and the manifestation of the biomarker strongly depending on the specific treatment regimen the patients received. In summary, this dissertation demonstrates the rich diversity of information that can be discovered through these imaging techniques. These multiscale imaging modalities can provide a translational platform for discoveries to move from cells to animal and ultimately validation in humans.2023-07-16T00:00:00

Shortwave-infrared meso-patterned imaging enables label-free mapping of tissue water and lipid content

Quantifying lipid and water content in tissues non-invasively is difficult, and no method exists to quantify lipids in blood non-invasively. Here the authors develop an imaging approach called shortwave infrared meso-patterned imaging (SWIR-MPI) to detect and spatially map tissue water and lipids in preclinical models