GLUT1-targeted near-infrared fluorescence molecular imaging for precise intraoperative detection of breast cancer
A Novel GLUT1-Targeted Fluorescence Imaging Tracer: Advances in Intraoperative Breast Cancer Detection
Background and Problem Statement
Breast cancer is one of the most common malignancies among women worldwide, with an estimated 2.3 million new cases and approximately 666,000 deaths globally in 2022. Surgical treatment for breast cancer typically includes breast-conserving surgery (BCS) and mastectomy. Compared to mastectomy, BCS combined with postoperative radiotherapy can achieve similar local control while maximizing the preservation of normal breast tissue. However, achieving a tumor-free surgical margin (i.e., a margin without cancer cells) is crucial for the success of BCS. Studies indicate that positive surgical margins significantly increase the risk of local recurrence, with rates ranging from 20-40%. To prevent recurrence and potential treatment failure in patients with positive margins, reoperation is often required, increasing surgical risk, cost, and psychological burden, and potentially affecting cosmetic outcomes for patients.
Currently, one of the main methods for assessing surgical margins intraoperatively is frozen section analysis. However, this method is time-consuming and prone to sampling errors. Conventional radiologic approaches (such as ultrasound, X-ray specimen mammography, MRI, and CT) have been applied for intraoperative margin assessment, but these techniques are not cancer-specific and cannot provide real-time imaging. Thus, there is an urgent need to develop cancer-specific, real-time intraoperative imaging techniques. Recently, optical imaging techniques based on fluorescence molecular imaging (FMI) and cancer-specific tracers have brought new possibilities for intraoperative margin assessment and precise tumor resection. However, most optical tracers lack broad tumor applicability.
To address this issue, high glucose uptake and glycolytic metabolism have been recognized as characteristics of cancer, and their transport depends on cell membrane glucose transporters (GLUTs). Specifically, GLUT1 is highly expressed in various cancers and is considered a potential novel target for fluorescence imaging during breast cancer surgery. This study aims to develop a new GLUT1-targeted near-infrared (NIR) fluorescence tracer, WZB117-Cy7.5, and evaluate its potential in real-time intraoperative detection and diagnosis of breast cancer.
Study Source and Author Information
This study was a collaborative effort among research teams from Shantou Central Hospital, Peking University Third Hospital, and the Chinese Academy of Sciences. The primary authors include Si-Qi Qiu, Xiao-Feng He, and Xiao-Long Liang. The article was published in 2025 in the “European Journal of Nuclear Medicine and Molecular Imaging.”
Detailed Study Process and Methodology
1. Assessment of GLUT1 Expression
The research team used the Gene Expression Profiling Interactive Analysis (GEPIA) platform to compare GLUT1 mRNA expression levels between breast cancer and normal breast tissues. Additionally, using Cancer Cell Line Encyclopedia (CCLE) data, they analyzed the distribution of GLUT1 expression across different breast cancer cell lines and found high expression across various subtypes.
Subsequently, immunohistochemical detection was performed on biological samples from 47 human breast cancer patients, confirming high GLUT1 expression levels in breast cancer tissues and consistent expression regardless of molecular subtype.
2. Synthesis and Characterization of WZB117-Cy7.5
The research team synthesized the WZB117-Cy7.5 tracer by chemically coupling the GLUT1 competitive inhibitor WZB117 with the near-infrared dye Cy7.5.
- Instrumentation and Methods: The substance was purified by high-performance liquid chromatography (HPLC) and its chemical structure was verified by mass spectrometry, achieving a purity of 98.68%.
- Spectral Properties: The tracer displayed ideal absorption spectra (600–800 nm range with a peak at 773 nm), providing the advantages of deeper tissue penetration and low background signal.
The binding affinity of WZB117 to GLUT1 was measured at 1.51e^-04 through surface plasmon resonance (SPR) experiments.
3. In Vitro Binding Ability Testing of the Tracer
Flow cytometry and confocal microscopy experiments demonstrated the specific binding ability of WZB117-Cy7.5 in murine breast cancer 4T1 cells and human breast cancer cell lines (e.g., MDA-MB-231). Experiments showed stronger fluorescence signals in these breast cancer cell lines compared to free Cy7.5, and this binding was competitively inhibited by WZB117, further confirming its target specificity.
4. In Vivo and Ex Vivo Fluorescence Imaging in Animal Models
A 4T1 tumor mouse model was used to assess the in vivo distribution and imaging performance of WZB117-Cy7.5. The tracer exhibited detectable tumor fluorescence signals 2 hours post-injection, peaking at 6 hours. Ex vivo fluorescence imaging confirmed WZB117-Cy7.5 primarily accumulated in tumor regions, with relatively lower background signals in the liver and kidneys.
Research Results and Findings
1. Diagnostic Performance in Ex Vivo Studies
The research team applied WZB117-Cy7.5 tracer spray on ex vivo tissue samples from 60 fresh breast cancer surgical specimens.
- Data Analysis: Fluorescence quantification and ROC curves (receiver operating characteristic curves) were used to evaluate the tracer’s diagnostic performance. The results showed stronger fluorescence signals in tumor tissues than in corresponding normal tissues, with an AUC of 0.963 for breast cancer diagnosis.
- Subtype Analysis: Further analysis across different molecular subtypes (e.g., HR+/HER2-, HER2+, and triple-negative breast cancer) indicated that WZB117-Cy7.5 is applicable to all subtypes.
2. Validation of GLUT1 and Fluorescence Signals
Immunohistochemistry results showed high fluorescence signal areas coincided with high GLUT1 expression areas, confirming that the fluorescence signal of the tracer indeed originated from GLUT1-expressing tumor cells.
3. Biosafety Evaluation
In animal experiments, histological examination of major organs (heart, liver, spleen, lung, kidney, brain) after intravenous injection of WZB117-Cy7.5 showed no abnormalities, and liver and kidney function markers (ALT, AST, and BUN) remained unchanged, indicating good biosafety of the tracer.
Conclusions and Research Significance
This study presents the first systematic validation of high diagnostic accuracy for a GLUT1-targeted tracer in fresh breast cancer surgical specimens. The potential application of WZB117-Cy7.5 in rapid intraoperative fluorescence imaging offers a new approach for margin assessment and tumor resection in BCS. Furthermore, the tracer might assist pathologists in tissue sampling, reducing sampling errors associated with frozen section analysis.
Research Highlights:
1. Pan-subtype Applicability: The tracer demonstrates high sensitivity across all breast cancer molecular subtypes, exhibiting general applicability.
2. Flexible Time Window: Detection within 2 hours post-injection allows for a short imaging window suitable for rapid clinical application.
3. High Biosafety: Good tolerance and safety observed in animal trials lay the foundation for clinical translation.
Future Prospects
The study plans to conduct more clinical trials to further evaluate the practical application effects of WZB117-Cy7.5-based real-time intraoperative decision-making in BCS and explore its role in reducing positive margin rates and reoperation. Additionally, combining artificial intelligence technology to further enhance fluorescence signal detection and residual tumor tissue differentiation accuracy will become a new focus in the next research phase.