Abstract P3-02-10: Balixafortide-functionalized down-conversion NIR-IIb nanoparticles for lymph node-invaded breast cancer detection
Authors: Zhu Yuan-Yuan , Zhang Yong-Qu , Wang Zun , Chen Min , Zhang Guo-Jun 
Published: March 2022

Abstract
Introduction:. Breast cancer is the most common malignant tumor in women, which seriously affects the physical and mental health of women. Tumor metastasis detection is the key for tumor staging and therapeutic decision-making as well as prognosis. Since tumor cells spread mainly through lymphatic to distant organs, sentinel lymph node biopsy (SLNB) has emerged as the standard method for staging clinically node-negative breast cancer. During the procedure, pathological methods are needed to evaluate the metastatic status of lymph nodes. However, the sentinel lymph nodes are tumor-free in more than 70% of patients who received SLNB, leading to unnecessary treatments and complications. Hence, how to evaluate the metastatic status of SLN noninvasively and intraoperatively to avoid unnecessary SLNB is a urgent problem to be solved. Nowadays, the gold standard for detection and targeted excision of the sentinel lymph node is preoperative lymphoscintigraphy with technetium-99m or methylene blue. However, the technetium-99m method has radiation hazards.More noteworthy, the operator needs to master learning curve to improve the accuracy of SLNB surgery based on the methylene blue. It is urgent to look for alternative methodologies such as fluorescence-based imaging to improve accuracy of SLNB and overall safety. Noteworthy, the fluorescent imaging in the NIR-IIb 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, noninvasively and dynamically in vivo. We have successfully synthesized a targeting CXCR4 probe NaErF4@ NaYF4@PAA@Balixafortide (ErNPs@POL6326). From vivo to vitro, from macro to microscopic, we investigated that the probe has good biocompatibility, specificity and sensitivity. And the probe can assess the status of SLN noninvasively with which fluorescence signal is positively correlated with lymph node metastasis. Methods:. 1. Appearance, stability, fluorescence emission spectrum and penetration were performed to investigate the characterization of the probe. 2. Cytotoxicity assay and pathology of important organs were examined to verify probe safety. 3. Breast cancer cell lines with different expression level of CXCR4 were used to analyze the sensitivity of the probe in vitro. Control probe ErNPs@PAA and free POL6326 blocking assays are used to examine the specificity. 4. 4T1 tumor-bearing mouse modal was performed to investigate the characterization of the probe. 5. Probe was subcutaneously injected into both hind footpad of the Balb/c mice bearing lymphatic metastasis and then fluorescent imaging is taken in the NIR-IIb window. Results:. 1. ErNPs @POL6326 was successfully synthesized with good stability and high intensity of NIR-IIb fluorescent. 2. ErNPs@POL6326 could specifically target different expression level of CXCR4 in breast cancer cell line compared with ErNPs@PAA. 3. ErNPs@POL6326 could specifically accumulate in 4T1 subcutaneous tumor compared with ErNPs@PAA, with tumor-to-background ratiomaximized at 36 h post injection. 4. In living mice with SLN metastasis of 4T1 tumors showed that ErNPs @POL6326 could easily drain into SLN and target to the metastatic 4T1 tumor cells, resulting in strong fluorescence signals. Summary:. Our results demonstrate that ErNPs @POL6326 can noninvasively and dynamically evaluate the status of SLN in real-time and confirm that fluorescence signal is positively correlated with lymph node metastasis. In the future, we will conduct in-depth analysis the long term toxicology of ErNPs @POL6326 in vivo. In summary, we believe that these results will provide research basis for optimizing the current diagnosis and treatment process of SLNB and improving the accuracy of diagnosis and treatment.
Citation Format: Yuan-Yuan Zhu, Yong-Qu Zhang, Zun Wang, Min Chen, Guo-Jun Zhang. Balixafortide-functionalized down-conversion NIR-IIb nanoparticles for lymph node-invaded breast cancer detection [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-02-10.