A Protease-Activated Fluorescent Probe Allows Rapid Visualization of Keratinocyte Carcinoma during Excision.

Keratinocyte carcinomas, including basal and squamous cell carcinomas, are the most common human cancers worldwide. While 75% of all keratinocyte carcinoma (4 million annual cases in the United States) are treated with conventional excision, this surgical modality has much lower cure rates than Mohs micrographic surgery, likely due to the bread-loaf histopathologic assessment that visualizes <1% of the tissue margins. A quenched protease-activated fluorescent probe 6qcNIR, which produces a signal only in the protease-rich tumor microenvironment, was topically applied to 90 specimens immediately following excision.

Molecular imaging and validation of margins in surgically excised nonmelanoma skin cancer specimens.

In an effort to increase the efficiency and cure rate of nonmelanoma skin cancer (NMSC) excisions, we have developed a point-of-care method of imaging and evaluation of skin cancer margins. We evaluate the skin surgical specimens using a smart, near-infrared probe (6qcNIR) that fluoresces in the presence of cathepsin proteases overexpressed in NMSC. Imaging is done with an inverted, flying-spot fluorescence scanner that reduces scatter, giving a 70% improved step response as compared to a conventional imaging system.