Letter to the Editor: DAF-FM fluorescent probe: Advancing early detection of esophagitis-to-cancer transformation through nitric oxide imaging

Abstract

Chen et al published a study in the recent issue of World Journal of Gastrointestinal Surgery evaluated the high-performance fluorescent probe DAF-FM provides a significant advancement in early esophageal cancer detection. DAF-FM enables real-time monitoring of nitric oxide during esophagitis-to-cancer transformation, with concentration-dependent and time-dependent fluorescence, lysosomal targeting, and low cytotoxicity. In preclinical models, DAF-FM fluorescence strongly correlates with tumor volume (R² = 0.87) and demonstrates superior sensitivity compared to endoscopic biopsy. These findings position DAF-FM as a rapid, non-invasive, and clinically relevant tool for early diagnosis and treatment monitoring in high-risk esophagitis patients.

Key Words: DAF-FM; Fluorescent probe; Nitric oxide; Esophagitis; Early detection; Molecular imaging; Esophageal cancer; Translational research

Core Tip: This letter highlights the translational potential of DAF-FM for visualizing nitric oxide dynamics in esophagitis-to-cancer progression. By bridging molecular pathophysiology and clinical imaging, DAF-FM could enhance early detection, improve personalized therapy monitoring, and expedite the translation of molecular insights into practical clinical applications.

TO THE EDITOR

Chen et al[1] published a study in the recent issue of World Journal of Gastrointestinal Surgery evaluated the high-performance fluorescent probe DAF-FM presents a timely and impactful advancement in early detection strategies for esophageal carcinogenesis. Given that esophageal cancer often evolves silently through chronic inflammation, dysplasia, and eventual malignancy[2], identifying molecular alterations during early transformation remains essential for improving prognosis[3]. By enabling real-time visualization of nitric oxide (NO), a critical mediator of esophageal carcinogenesis, DAF-FM bridges a crucial gap between molecular pathology and clinical imaging.

DAF-FM AS A REDOX-SENSITIVE IMAGING TOOL

DAF-FM exhibits strong concentration- and time-dependent fluorescence, with efficient lysosomal localization (Pearson coefficient = 0.82 ± 0.03) and minimal cytotoxicity (82.3% ± 4.1% cell viability at 50 μmol/L)[4]. These attributes position DAF-FM as a sensitive, rapid, and non-invasive imaging tool capable of detecting early pathophysiological NO fluctuations and monitoring therapeutic responses in real time[5].

Incorporating the bimodal (“Yin-Yang“) role of NO

NO is known to have a dual effect in cancer biology: (1) Low to moderate levels can be pro-tumorigenic, promoting angiogenesis, DNA damage, and metastasis; and (2) High, sustained levels (typically mediated by inducible NO synthase) exert anti-tumor, cytotoxic effects[6].

This well-established “Yin-Yang” behavior underscores the need for quantitative, dynamic, real-time imaging of NO. The strong correlation observed in the original manuscript between DAF-FM fluorescence and tumor volume (R² = 0.87) demonstrates the probe’s unique ability to resolve this biological ambiguity in esophageal carcinogenesis[1].

Furthermore, DAF-FM outperformed conventional endoscopic biopsy (92.5% vs 78.3% diagnostic sensitivity)[7], suggesting that molecular-level NO imaging may provide earlier insight into malignant transformation than morphology-based histology.

INTEGRATION WITH THERAPEUTIC MONITORING

Real-time NO imaging using DAF-FM demonstrated responsiveness to chemoradiotherapy, particularly 5-fluorouracil and radiotherapy-induced NO changes[8]. Because nuclear factor kappa B activation, inflammatory signaling, and inducible NO synthase expression play pivotal roles in esophageal carcinogenesis[9,10], DAF-FM provides not only diagnostic information but also mechanistic insight into tumor response dynamics. This makes the probe uniquely suited for personalized therapy monitoring, enabling clinicians to adapt treatment strategies based on molecular response rather than delayed clinical endpoints[11,12].

FUTURE DIRECTIONS AND CLINICAL TRANSLATION

While DAF-FM is highly promising, several enhancements will accelerate its clinical integration.

Development of near-infrared derivatives

Because visible-light fluorophores such as DAF-FM are limited by tissue autofluorescence and shallow penetration, future translational development should focus on: (1) Designing near-infrared (NIR) derivatives or analogs of DAF-FM (700-1000 nm); and (2) Encapsulation within nanoparticle carriers to improve stability and delivery NIR imaging provides deeper tissue penetration and improved signal-to-background ratios, enabling applications in real-time endoscopy, fluorescence-guided biopsy, and intraoperative tumor margin assessment[13].

Multi-modal diagnostic ecosystem

DAF-FM could be integrated with: (1) Multiphoton microscopy; (2) Positron emission tomography or hybrid positron emission tomography-optical systems; and (3) Molecular biomarkers such as ctDNA, inflammatory cytokines, or metabolic signals.

This would enhance diagnostic specificity and support a multi-scale, multi-modal precision oncology framework.

Expanded validation in diverse populations

Multi-center, multi-national studies are essential to: (1) Confirm reproducibility; (2) Address epidemiological variability; and (3) Evaluate performance in real-world clinical workflows.

Longitudinal and prognostic studies

Future studies should correlate DAF-FM fluorescence with: (1) Progression-free survival; (2) Recurrence rates; and (3) Treatment response dynamics.

This will determine the probe’s clinical predictive value beyond early detection.

Clinical practicality and workflow integration

Given its rapid imaging capability (results within 30 minutes, compared to approximately 48 hours for biopsy), DAF-FM is well suited for: (1) Bedside screening; (2) Point-of-care evaluation; and (3) Real-time endoscopic decision-making.

Such integration could significantly reduce diagnostic delays in high-risk esophagitis patients.

CONCLUSION

DAF-FM represents an innovative redox-sensitive imaging probe with significant translational potential. By enabling real-time visualization of NO during esophagitis-to-cancer transformation, DAF-FM provides a mechanistically grounded, non-invasive alternative to traditional biopsy. Incorporating its use into clinical workflows – supported by multi-center validation, integration with molecular biomarkers, and future development of NIR analogs – could meaningfully enhance early detection and personalized therapeutic monitoring in esophageal cancer. This commentary outlines the necessary translational roadmap that can help evolve DAF-FM from a promising preclinical tool to a routine component of precision gastro-oncology.

ACKNOWLEDGEMENTS

The authors express their gratitude to the researchers of the original study by Chen et al for their significant contribution to advancing the understanding of nitric oxide imaging in esophageal carcinogenesis. The authors also thank the faculty and research support staff of SCSSS’s Sitabai Thite College of Pharmacy, Shirur, for providing academic encouragement during the preparation of manuscript.