Molecular imaging assisted surgery improves survival in a murine head and neck cancer model

Novel color fluorescence imaging for sentinel lymph node detection in oral and oropharyngeal cancer

AIM

Fluorescence imaging (FI) using indocyanine green (ICG) is a noteworthy alternative technique for sentinel lymph node (SLN) detection without radiation exposure in oral cavity and oropharynx cancer. However, conventional FI is monochrome, so the visibility is limited. This study assessed whether color FI using the HyperEye Medical System (HEMS) is feasible as an alternative for SLN detection.

METHODS

Patients with previously untreated cT1-2N0 oral or oropharyngeal cancer who were to undergo primary tumor resection and elective neck dissection (END) in our hospital were enrolled from November 2012 to March 2016. The patients underwent SLN detection for biopsy via the HEMS following the injection of ICG solution around the primary lesion before neck dissection. The visibility and the diagnostic accuracy of the imaging were evaluated.

RESULTS

SLNs were visualized in all eight cases; however, transcutaneous fluorescence detection was not observed in all cases. Utilizing color mode imaging simplified harvest by clearly discriminating SLNs from surrounding structures, while the monochrome mode proved to be more sensitive for detection. Two cases showed occult metastases on both sentinel and regional nodes. The identification and false negative rates were 100% and 0%, respectively. There were no complications incurred due to this method.

CONCLUSION

Our results suggest that color FI with the HEMS allows for the accurate and safe harvest of SLNs with a preparatory skin incision. Although there is room for improvement of sensitivity, this easy-to-handle procedure might provide the potential to expand the role of the ICG method for SLN detection in head and neck cancer.

Self-assembling as regular nanoparticles dramatically minimizes photobleaching of tumour-targeted GFP

Fluorescent proteins are useful imaging and theranostic agents, but their potential superiority over alternative dyes is weakened by substantial photobleaching under irradiation. Enhancing protein photostability has been attempted through diverse strategies, with irregular results and limited applicability. In this context, we wondered if the controlled oligomerization of Green Fluorescent Protein (GFP) as nanoscale supramolecular complexes could stabilize the fluorophore through the newly formed protein-protein contacts, and thus, enhance its global photostability. For that, we have here analyzed the photobleaching profile of several GFP versions, engineered to self-assemble as tumour-homing nanoparticles with different targeting, size and structural stability. This has been done under prolonged irradiation in confocal laser scanning microscopy and by small-angle X-ray scattering. The results show that the oligomerization of GFP at the nanoscale enhances, by more than seven-fold, the stability of fluorescence emission. Interestingly, GFP nanoparticles are much more resistant to X-ray damage than the building block counterparts, indicating that the gained photostability is linked to enhanced structural resistance to radiation. Therefore, the controlled oligomerization of self-assembling fluorescent proteins as protein nanoparticles is a simple, versatile and powerful method to enhance their photostability for uses in precision imaging and therapy. STATEMENT OF SIGNIFICANCE: Fluorescent protein assembly into regular and highly symmetric nanoscale structures has been identified to confer enhanced structural stability against radiation stresses dramatically reducing their photobleaching. Being this the main bottleneck in the use of fluorescent proteins for imaging and theranostics, this protein architecture engineering principle appears as a powerful method to enhance their photostability for a broad applicability in precision imaging, drug delivery and theranostics.

Surgical molecular navigation with ratiometric activatable cell penetrating peptide for intraoperative identification and resection of small salivary gland cancers

BACKGROUND

We evaluated the use of intraoperative fluorescence guidance by enzymatically cleavable ratiometric activatable cell-penetrating peptide (RACPPPLGC(Me)AG) containing Cy5 as a fluorescent donor and Cy7 as a fluorescent acceptor for salivary gland cancer surgery in a mouse model.

METHODS

Surgical resection of small parotid gland cancers in mice was performed with fluorescence guidance or white light (WL) imaging alone. Tumor identification accuracy, operating time, and tumor-free survival were compared.

RESULTS

RACPP guidance aided tumor detection (positive histology in 90% [27/30] vs 48% [15/31] for WL; p < .001). An approximate 25% ratiometric signal increase as the threshold to distinguish between tumor and adjacent tissue, yielded >90% detection sensitivity and specificity. Operating time was reduced by 54% (p < .001), and tumor-free survival was increased with RACPP guidance (p = .025).

CONCLUSION

RACPP provides real-time intraoperative guidance leading to improved survival. Ratiometric signal thresholds can be set according to desired detection accuracy levels for future RACPP applications.

Application of infrared-based molecular imaging to a mouse model with head and neck cancer

BACKGROUND

This study investigated whether near infrared (NIR) or visible fluorescent molecular imaging produced a better representation of a mouse model with head and neck squamous cell carcinoma (HNSCC). Additionally, the study explored whether epidermal growth factor receptor (EGFR)-targeted probes could play an important role in the diagnosis of HNSCC.

METHODS

An orthotopic mouse model of HNSCC labeled with the NIR fluorophore, infrared fluorescent protein (iRFP), was developed and monitored noninvasively in real time. The tumors were further evaluated using tumor-specific EGFR-targeted probes conjugated with an NIR dye (IRDye800), or a visible fluorescent protein.

RESULTS

The iRFP cell line produced better results than cells emitting visible light when studying local, distant, and deep tumors in the mouse model. The EGFR-targeted probe conjugated with IRDye800 accurately detected tumor perimeters.

CONCLUSION

This model has great potential as a unique tool in the study of HNSCC tumor development. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1351-E1357, 2016.

Operative margin control with high-resolution optical microendoscopy for head and neck squamous cell carcinoma

OBJECTIVES/HYPOTHESIS

High-resolution microendoscopy (HRME) provides real-time visualization of the mucosal surface in the upper aerodigestive tract. This technology allows noninvasive discrimination of benign and neoplastic epithelium and has potential applications for intraoperative margin detection.

STUDY DESIGN

Single institution, prospective, feasibility trial (phase I) of in vivo optical imaging.

METHODS

The study was conducted on patients with squamous cell carcinoma of the upper aerodigestive tract. High-resolution microendoscopy images obtained during surgery were correlated with histopathologic diagnosis to determine the ability of HRME to differentiate between benign and malignant mucosa. Blinded reviewers evaluated HRME images and made determinations of the status of the mucosa. Accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and interrater agreement between multiple raters were calculated to determine the accuracy of HRME imaging.

RESULTS

The mean accuracy of reviewers in differentiating neoplastic or benign mucosa was 95.1% (95% confidence interval [CI], 94%-96%). Sensitivity and specificity were 96% (95% CI, 94%-99%) and 95% (95 % CI, 90%-99%), respectively. The NPV was 98% (95% CI, 97%-99%), and PPV was 91% (95% CI, 85%-98%). The Fleiss kappa statistic for interrater reliability was 0.81, with a standard error of 0.014 and a 95% CI (0.78-0.84).

CONCLUSION

High-resolution microendoscopy allows real-time discrimination between benign and neoplastic mucosa. High levels of sensitivity and specificity can be obtained with this technology when interrogating mucosal surfaces. Despite several technical limitations, HRME shows promise as a technique for intraoperative margin control and platform for molecular imaging technologies.

LEVEL OF EVIDENCE

3b.