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Published on: September 19, 2014
Novel FAP-Targeted Heptamethine Cyanines for NIRF Imaging Applications
Rebecca Rizzo1, Martina Capozza1, Laura Conti1
1Department of Molecular Biotechnology and Health Sciences, University of Turin, Piazza Nizza 44/bis, Turin 10126, Italy.
Abstract:
Fibroblast activation protein (FAP) is a pan-cancer target that is useful for imaging, ideally all epithelial cancers. This work aimed to develop, characterize, and validate two novel FAP-targeted probes for optical imaging, both in vitro and in vivo. IRDye800CW and FNIRTag heptamethine cyanines were conjugated to the NH precursor of the well-known FAP inhibitor FAPI-46, which is widely employed in nuclear medicine. In addition to synthesis, the dyes were characterized in terms of physicochemical properties, biodistribution, and imaging performances in a breast cancer tumor model. FAPI-FNIRTag showed a stronger fluorescence and higher photostability compared to FAPI-IRDye800CW. Notably, both compounds exhibited strong tumor accumulation in TUBO breast cancer-bearing mice 24 h postadministration, suggesting potential for further investigation as fluorescence-guided surgery (FGS) agents.
Insights
Researchers developed two novel probes targeting Fibroblast Activation Protein (FAP) for optical imaging. Both probes showed tumor accumulation in mice, with FAPI-FNIRTag demonstrating superior fluorescence and stability for potential use in fluorescence-guided surgery.
Area of Science:
- Oncology
- Medical Imaging
- Bioconjugation Chemistry
Background:
- Fibroblast Activation Protein (FAP) is a promising pan-cancer target, particularly for epithelial cancers.
- Current imaging techniques require further development for enhanced specificity and efficacy.
- FAPI-46 is a well-established FAP inhibitor used in nuclear medicine.
Purpose of the Study:
- To develop and characterize novel FAP-targeted probes for optical imaging.
- To evaluate the in vitro and in vivo performance of these probes.
- To assess their potential as agents for fluorescence-guided surgery (FGS).
Main Methods:
- Conjugation of IRDye800CW and FNIRTag heptamethine cyanines to the FAPI-46 precursor.
- Characterization of physicochemical properties, biodistribution, and imaging performance.
- In vivo evaluation in a murine breast cancer tumor model.
Main Results:
- Two novel FAP-targeted probes, FAPI-IRDye800CW and FAPI-FNIRTag, were successfully synthesized and characterized.
- FAPI-FNIRTag exhibited enhanced fluorescence and photostability compared to FAPI-IRDye800CW.
- Both probes demonstrated significant tumor accumulation in vivo within 24 hours post-administration.
Conclusions:
- The developed FAP-targeted probes show promise for optical imaging applications.
- FAPI-FNIRTag presents favorable characteristics for potential clinical translation.
- These probes warrant further investigation as agents for fluorescence-guided surgery in various epithelial cancers.
