Optical metabolic imaging could be ideal for breast cancer research

Fluorescence optical imaging of the breast has the potential to capture dynamic metabolic response signaling malignancy, according to a review published online Oct. 15 in Cancer Research.

Optical metabolic imaging provides quick assessment of molecular response and could therefore be an advantage particularly in drug trials. Researchers including Melissa Skala, PhD, assistant professor of biomedical engineering at Vanderbilt University in Nashville, did an analysis of optical metabolic imaging and levels of cellular glycolysis in human breast cells with assays of lactate secretion and cellular glucose uptake. The team found that optical metabolic breast imaging correlated well with breast cell glycolytic activity and clarified metabolic differences in untransformed cells, various subtypes and those indicated as either positive or negative for HER2 breast cancer expression.

“Clinically and in preclinical drug development, there is a need for high-resolution, noninvasive, functional imaging tools to monitor and predict drug efficacy versus lack of efficacy,” wrote Skala et al.  “In cancer research, the primary endpoint of drug efficacy is tumor regression. However, cellular and molecular changes precede changes in tumor size. If these molecular endpoints could be identified and measured, they would provide biomarkers predictive of drug response or drug resistance.”

Current methods of metabolic breast imaging, including FDG PET, were noted to underperform in visualizing dynamic metabolic states when compared to optical metabolic imaging. In vivo optical metabolic imaging was sensitive to tumor growth curves and accounted for cellular changes from treatment with trastuzumab as soon as 48 hours after the drug was administered. This is in stark contrast to FDG PET, which took 12 days to register cellular changes. Optical metabolic imaging was pointed out as an aid in working with patients with HER2 genetic expression.

“Patients with HER2 gene-amplified breast cancers present with more aggressive disease and generally have a poor prognosis,” wrote Skala et al. “HER2 inhibitors such as the antibody trastuzumab (herceptin) provide substantial clinical benefits. However, the action of HER2 inhibitors is limited because of innate and acquired drug resistance.”

Despite this, optical metabolic imaging maintained sensitivity even when using Trastuzumab-resistant xenografts. Additional research is needed to glean the imaging technique’s full potential in breast cancer imaging.