Design of a Pan-Tumor Fluorescence Imaging Cocktail for Fluorescence-Guided Surgery

Area of Science:

• Oncology
• Surgical Innovation
• Molecular Imaging

Background:

• Fluorescence-guided surgery (FGS) improves cancer resection but lacks a universal imaging agent.
• Current near-infrared (NIR) fluorophores target specific cancer types, limiting their broad applicability.
• A need exists for a broad-spectrum imaging agent for intraoperative use.

Purpose of the Study:

• To develop and evaluate a novel FAP-targeted NIR fluorophore (FAP9-S0456) in combination with pafolacianine for broad-spectrum cancer imaging.
• To assess the affinity and specificity of the novel FAP ligand (FAP9).
• To determine the optimal ratio of the two fluorophores for maximum tumor visualization.

Main Methods:

• Design, synthesis, and characterization of a novel FAP ligand (FAP9).
• Determination of FAP9's binding affinity and specificity.
• In vivo imaging studies in murine models using FAP9-S0456 and pafolacianine in various combinations.
• Quantification of tumor fluorescence and tumor-to-background ratios.

Main Results:

• The novel FAP ligand FAP9 demonstrated high affinity (Kd ~ 2 nM) and specificity (>2000-fold) for FAP.
• The combination of FAP9-S0456 and pafolacianine consistently improved tumor imaging compared to either agent alone across seven tumor models.
• No significant toxicities were observed with the dual-dye combination.

Conclusions:

• A cocktail of FAP9-S0456 and pafolacianine shows potential as a broad-spectrum agent for intraoperative fluorescence imaging of solid tumors.
• This combination enhances tumor detection by targeting both cancer cells (via folate receptors) and tumor-associated myofibroblasts (via FAP).
• Further evaluation in clinical settings is warranted to validate its efficacy in human cancers.