Detection of colonic dysplasia in vivo using a targeted heptapeptide and confocal microendoscopy

Abstract

A combination of targeted probes and new imaging technologies provides a powerful set of tools with the potential to improve the early detection of cancer. To develop a probe for detecting colon cancer, we screened phage display peptide libraries against fresh human colonic adenomas for high-affinity ligands with preferential binding to premalignant tissue. We identified a specific heptapeptide sequence, VRPMPLQ, which we synthesized, conjugated with fluorescein and tested in patients undergoing colonoscopy. We imaged topically administered peptide using a fluorescence confocal microendoscope delivered through the instrument channel of a standard colonoscope. In vivo images were acquired at 12 frames per second with 50-microm working distance and 2.5-microm (transverse) and 20-microm (axial) resolution. The fluorescein-conjugated peptide bound more strongly to dysplastic colonocytes than to adjacent normal cells with 81% sensitivity and 82% specificity. This methodology represents a promising diagnostic imaging approach for the early detection of colorectal cancer and potentially of other epithelial malignancies.

Selective treatment and monitoring of disseminated cancer micrometastases in vivo using dual-function, activatable immunoconjugates

“…Microendoscopy has taken microscopy to new depths in vivo using miniaturized optics (46), and this technology is emerging for "optical biopsy" of cancer (32,(47)(48)(49)(50)(51)(52)(53). Through the development of in vivo fluorescence microendoscopy with activatable immunoconjugates and automated image analysis algorithms (Fig.…”

A Raman-based endoscopic strategy for multiplexed molecular imaging

“…Some techniques look at basic tissue architecture through fluorescence or characterization of crevices and concave areas with the use of chromogenic dyes, whereas other techniques focus on microscopic subcellular structural changes between normal and dysplastic lesions (24). Other researchers have recognized the importance of adding a functional component to guide endoscopy by using molecularly targeted fluorescent probes, which have shown success in both mouse models and humans (25)(26)(27). Although these techniques have great potential to improve the endoscopic detection of pathological conditions in the colon, these fluorescence-based techniques cannot offer the multiplexing capabilities of our nanobased Raman endoscopy strategy.…”

“…Intraoperative strategies can also be an important area of application for this approach. With the discovery of new cancer biomarkers, corresponding new molecular targeting moieties can be developed and exploited for improved tumor specificity (26,47,48). Moreover, to improve early cancer detection further, one could couple the inherently good specificity associated with acquiring intrinsic Raman signal from cancerous tissues with the unparalleled sensitivity and multiplexing capabilities offered by using tumor-targeted SERS nanoparticles as contrast agents.…”

Imaging Glycosylation In Vivo by Metabolic Labeling and Magnetic Resonance Imaging

“…Various probes have been reported for imaging glycosylation in vivo, including antibodies,4 peptides,5 boronic acid derivatives,6 and lectins 7. Most approaches give a static view of cell‐surface glycosylation.…”