<em>In Vivo</em> Breast Cancer Characterization Imaging using Two Monoclonal Antibodies Activatably Labeled with Near Infrared Fluorophores

Antibody-based immunohistochemistry (IHC) of tissue specimens is a common method of identifying expressed proteins in cancer cells. Molecular imaging is a potential method of performing similar IHC studies in vivo without the requirement for biopsy or tumor excision. This article discusses the use of optically activatable imaging agents, which are only fluorescent when bound to their cognate receptor, opening the possibility of doing in vivo multi-color IHC.