Abstract 5778: Intra-operative visualization of metastatic sentinel lymph nodes in early breast cancer: An approach to omission of axillary surgery

Abstract Purpose: Sentinel lymph node biopsy (SLNB) has become the established approach, and is the standard of care for staging clinically node-negative breast cancer. The pathological examination is the golden standard during this procedure. However, its sensitivity is less than 80%, and requires significant time, manpower, and material resources. Noteworthy, the fluorescent imaging in the second near-infrared region (NIR-II) window offers greater tissue penetration and contrast compared to conventional imaging, which is more suitable for detecting the metastatic status of SLN in real-time and dynamically in vivo. In this study, we developed a new technology that can quickly identify the metastatic status of SLN both in vivo and the resected SLN tissue during the operation. Methods: 1. Characterization and biosafety of the probe ICG-POL6326 were performed. 2. The targeting efficacy of probe was confirmed through in vitro fluorescence co-localization experiments and in vivo fluorescence imaging in tumor-bearing and SLN metastatic mouse model. 3. SLN from mice with lymphatic metastasis were excised and incubated with ICG-POL6326 for subsequent imaging by a NIR-II system to evaluate the efficacy of ex vivo incubation and imaging methods. 4. Ten surgically removed SLN tissues from ten breast cancer patients undergoing resection were incubated with the probe immediately and imaged to identify the metastatic status of SLN. The accuracy of fluorescence imaging was confirmed by pathological diagnosis. Results: 1. ICG-POL6326 was successfully synthesized with good stability, biocompatibility with high intensity of NIR-II fluorescent imaging. 2. ICG-POL6326 could specifically target 4T1-Luc and MDA-MB-231-Luc cell which with high CXCR4 expression compared with ICG-NHS. 3.ICG-POL6326 group exhibited a 3.15-fold higher maximum signal-to-background ratio (SBR) compared to the ICG-NHS group (p < 0.0001) in 4T1-Luc subcutaneous tumor models. 4. ICG-POL6326 was able to detected the metastatic status of SLN in 4T1-Luc SLN metastasis models. the SBR of metastasis SLN was 4.1-fold higher than normal SLN (p < 0.001). In addition, via co-incubation of ICG-POL6326, the metastatic SLN exhibited a higher MFI relative to normal SLN with a TNR more than 5 (tumor to normal ratio) (p < 0.0001). 5. This new technology yielded more than 90.31% specificity and 100% sensitivity in identifying the metastatic SLN. Summary: ICG-POL6326 can dynamically evaluate the status of SLN in real-time, with a positive correlation between fluorescence signal and lymph node metastasis. By using ICG-POL6326 to incubate freshly isolated SLN during surgery, the probes can quickly accumulate in SLN invaded by breast cancer cells and identify the metastatic status of SLN. This technology is expected to be used for rapid intraoperative pathological detection and identification of metastatic SLN. Citation Format: Yuanyuan Zhu, Wei-Ling Chen, Zao Wu, Jun-hong Chen, Ting-wen Guo, Guo-Jun Zhang. Intra-operative visualization of metastatic sentinel lymph nodes in early breast cancer: An approach to omission of axillary surgery [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5778.