This article by Wilson, et al. uses a clinically translatable and commercially available photoacoustic contrast agent (ICG) conjugated with an antibody specific to breast cancer cells to perform in vivo molecular imaging in an orthotopic mouse model of breast cancer.Article Summary: • Breast cancer lacks diagnostic accuracy, therefore noninvasive methods to detect benign from malignant lesions are needed • Photoacoustic imaging can be combined with ultrasound as a noninvasive diagnostic tool • Purpose: To evaluate an antibody-ICG conjugate, and use photoacoustic imaging to differentiate normal breast tissue from breast cancer by imaging B7-H3, a novel breast cancer associated molecular target. • Histological validation of epithelial expression of B7-H3 in human samples was performed and replicated in a transgenic mouse model of breast cancer development • Development of a clinically translatable, antibody-dye conjugate contrast agent using a commercially available ICG fluorophore and subsequent in vitro testing for cellular uptake was done and compared to control • In vivo B-Mode and multispectral photoacoustic imaging was performed on animals after i.v. administration of targeted anti-B7-H3 ICG conjugate as well as controls and uptake and distribution in breast tumors was visualized and confirmed by histology
Conclusion: This study demonstrates the synthesis of a molecularly specific conjugate of an antibody to a commercially available ICG dye and its in vivo use to distinguish between breast cancer versus normal mammary tissue using multispectral photoacoustic imaging. In addition, dye which was taken up by the target cell was able to be differentiated from freely circulating and nonspecific control agents based upon its spectral properties as detected with photoacoustic imaging.
Reference: Wilson KE, Bachawal S V., Abou-Elkacem L, et al. Spectroscopic Photoacoustic Molecular Imaging of Breast Cancer using a B7-H3-targeted ICG Contrast Agent. Theranostics. 2017;7(6):1463-1476. Available from: http://www.thno.org/v07p1463.pdf