Mapping Sentinel Lymph Node Metastasis by Dual-probe Optical Imaging

Abstract

Purpose: Sentinel lymph node biopsy (SLNB) has emerged as the preferred standard procedure in patients with breast cancer, melanoma and other types of cancer. Herein, we developed a method to intra-operatively map SLNs and differentiate tumor metastases within SLNs at the same time, with the aim to provide more accurate and real-time intraoperative guidance. Experimental Design: Hyaluronic acid (HA), a ligand of lymphatic vessel endothelial hyaluronan receptor (LYVE)-1, is employed as a SLN mapping agent after being conjugated with a near-infrared fluorophore (Cy5.5). Different sized HAs (5, 10 and 20K) were tested in normal mice and mice with localized inflammation to optimize LN retention time and signal to background ratio. Cetuximab, an antibody against epidermal growth factor receptor (EGFR), and trastuzumab, an antibody against human epidermal growth factor receptor 2 (HER2), were labeled with near-infrared fluorophore (IRDye800) for detecting metastatic tumors. LN metastasis model was developed by hock injection of firefly luciferase engineered human head neck squamous carcinoma cancer UM-SCC-22B cells or human ovarian cancer SKOV-3 cells. The metastases within LNs were confirmed by bioluminescence imaging (BLI). IRDye800-Antibodies were intravenously administered 24 h before local administration of Cy5.5-HA. Optical imaging was then performed to identify nodal metastases. Results: Binding of HA with LYVE-1 was confirmed by ELISA and fluorescence staining. HA with a size of 10K was chosen based on the favorable migration and retention profile. After sequential administration of IRDye800-antibodies intravenously and Cy5.5-HA locally to a mouse model with LN metastases and fluorescence optical imaging, partially metastasized LNs were successfully distinguished from un-metastasized LNs and fully tumor occupied LNs, based on the different signal patterns. Conclusions: Fluorophore conjugated HA is a potential lymphatic mapping agent for SLNB. Dual-tracer imaging with the combination of lymphatic mapping agents and tumor targeting agents can identify tumor metastases within SLNs, thus may provide accurate and real-time intra-operative guidance to spare the time spent waiting for a biopsy result.

Metastatic status of sentinel lymph nodes in breast cancer determined with photoacoustic microscopy via dual-targeting nanoparticles

“…Yang et al used HA of different molecular weights (5K/10K/15K) as SLN mapping agents and reported that 10K HA had favourable migration and retention profiles because it binds to Lyve-1 in LNs. The combination of HA and tumour-targeting antibodies (EGFR and HER2) can detect UM-SCC-22B tumour metastasis in SLNs 41 . However, this method of identifying T-MLNs is not ideal because it can only identify partial and fully occupied SLNs due to the minimal blood supply able to deliver the imaging probes to micrometastases and the simultaneous injection of antibody and HA, which should be separated by 24 h. In our study, we found that 5K-HA-HPPS rapidly (<10 min) migrated to pLNs and showed prolonged retention (>12 h) compared with 15K-HA-HPPS.…”

Imaging of Metastatic Cancer Cells in Sentinel Lymph Nodes using Affibody Probes and Possibility of a Theranostic Approach

“…The high sensitivity to nodal metastases, real-time imaging of lymphatic drainage patterns, and favorable blood clearance rate of the imaging probes led to a clinical trial of their capability in the specific determination of tumor-bearing lymph nodes [11,12,13]. Animal studies using antibodies were also conducted for the real-time imaging of lymph node metastases [14,15]. The NIR imaging probe cetuximab, an antibody against epidermal growth factor receptor (EGFR), and trastuzumab, an antibody against human epidermal growth factor receptor 2 (HER2), were labeled with a fluorophore (IRDye 800) and studied to determine their ability to detect tumor metastases within SLNs in a mouse model.…”

Cell-penetrating peptide-based nanovehicles potentiate lymph metastasis targeting and deep penetration for anti-metastasis therapy

“…The limited penetration of nanovehicles in tumor or metastases has been evidenced as a major factor limiting their therapeutic efficacy 47 - 49 . The lymph nodes near the original tumor are often the most susceptible sites of metastasis 8 , 50 , 51 . Therefore, the extent of tumor penetration and cellular internalization of r9-CN in primary tumor and metastatic lymph nodes were respectively evaluated.…”