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

Abstract

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<0.001). A ~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<0.001), tumor free survival was increased with RACPP guidance (p=0.025). Conclusions 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.

FRET Imaging of Enzyme‐Responsive HPMA Copolymer Conjugate

“…The advances in optical imaging technology, coupled with the development of new fluorescent probes and the increasing capability of computer software for image acquisition and analysis, have enabled FRET to elucidate molecular interactions inside living animals with improved sensitivity and spatial/temporal resolution. In particular, the development of near‐infrared fluorescence (NIRF) probes plays a vital role in real‐time imaging of dynamic molecular events in vivo . Thus, FRET imaging has a great potential for gaining insight into the function–mechanism relationship, especially for the development of drug delivery systems.…”

Early detection of squamous cell carcinoma in carcinogen induced oral cancer rodent model by ratiometric activatable cell penetrating peptides

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“…The cationic fragment of the RACPP is retained at the activation site, typically within the tumor. We have previously reported the use of MMP activatable cell penetrating peptides (ACPPs) probes for image guided surgery of tumors in various animal models of breast cancer [20], pancreatic cancer[21], melanoma and head and neck xenografts[22, 23]. We have also demonstrated significant correlation of ratiometric fluorescence (Cy5:Cy7) from the MMP cleavable RACPP with tumor burden in a pancreatic tumor mouse model [21].…”

Beyond the margins: real-time detection of cancer using targeted fluorophores

“…Initially, the Cy5 fluorophore is quenched owing to the close proximity to Cy7 but, upon cleavage, the Cy5 signal to Cy7 signal ratio increases over 40-fold 106 . The use of ratiometric imaging circumvents the problems associated with quantification using single-wavelength intensity measurements (dose-dependent uptake and PK characteristics), and the fluorophore exhibits fast activation (within 2 h) 106,138,139 .…”