Fluorescence-Guided Surgery of Rhabdomyosarcoma Using a B7-H3 Targeted Antibody-Fluorophore Conjugate
Ritika Gupta1, Evie G Ehrhorn2,3, Ashruti Pant1
1Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986120 Nebraska Medical Center, Omaha, Nebraska 68198-6858, United States of America.
Abstract:
Resection of sarcomas is often limited by infiltrative tumor growth and microscopic residual disease, underscoring the need for targeted intraoperative imaging strategies that enhance visualization of primary lesions and metastatic deposits. Here, a clinical-grade anti-B7-H3 antibody (MGA271) was conjugated to IRDye 800CW to generate MGA271-IRDye800, with an isotype control IgG-IRDye800 and unconjugated IRDye800 included as comparators. The resulting antibody-dye conjugates, MGA271-IRDye800 and IgG-IRDye800, exhibited an average dye-to-protein ratio of approximately 1. In vitro studies confirmed specific binding and strong fluorescence of MGA271-IRDye800 in six B7-H3-expressing sarcoma cell lines, with only minimal nonspecific uptake observed for control probes and in a B7-H3-negative control cell line. Based on these in vitro results, RH30 cells were selected to establish an orthotopic rhabdomyosarcoma xenograft model, in which in vivo near-infrared fluorescent imaging (NIRF) demonstrated substantially improved tumor visualization with MGA271-IRDye800 compared with IgG-IRDye800 and free IRDye800. Quantitative analysis confirmed significantly higher tumor-to-background ratios (TBRs) for MGA271-IRDye800 at 144 h (5.6 ± 2.2) compared with IgG-IRDye800 (2.7 ± 1.1) and unconjugated IRDye800 (1.0 ± 0.1), [p < 0.0001] supporting B7-H3-mediated tumor enrichment and superior contrast suitable for surgical navigation. During fluorescence-guided surgery, MGA271-IRDye800 enabled clear delineation of tumor margins, distinction of tumor from surrounding normal tissue and relevant background organs, and detection of otherwise occult micrometastatic lesions. Collectively, these findings demonstrate that B7-H3-targeted NIRF imaging with MGA271-IRDye800 offers sensitive and specific intraoperative visualization of sarcoma. This probe demonstrates strong potential for clinical translation as a molecular imaging agent to guide surgical resection, reduce residual disease, and ultimately improve outcomes for patients with B7-H3-expressing sarcomas.
Insights
This study developed MGA271-IRDye800, a novel imaging agent targeting B7-H3 for sarcoma surgery. It significantly improves tumor visualization and margin delineation, aiding in reducing residual disease for better patient outcomes.
Area of Science:
- Oncology
- Medical Imaging
- Molecular Biology
Background:
- Sarcoma resection is challenged by infiltrative growth and residual disease.
- Effective intraoperative imaging is crucial for complete tumor removal.
- B7-H3 is a potential target for sarcoma-specific imaging.
Purpose of the Study:
- To develop and evaluate MGA271-IRDye800, a near-infrared fluorescent imaging agent targeting B7-H3 for sarcoma.
- To assess its efficacy in visualizing primary and metastatic sarcoma lesions intraoperatively.
Main Methods:
- Conjugation of anti-B7-H3 antibody (MGA271) to IRDye800CW.
- In vitro studies using B7-H3-expressing and negative sarcoma cell lines.
- In vivo near-infrared fluorescent imaging (NIRF) in an orthotopic rhabdomyosarcoma xenograft model.
Main Results:
- MGA271-IRDye800 showed specific binding and strong fluorescence in vitro.
- In vivo NIRF imaging demonstrated significantly improved tumor visualization and higher tumor-to-background ratios (TBRs) compared to controls.
- The agent enabled clear delineation of tumor margins and detection of micrometastases during fluorescence-guided surgery.
Conclusions:
- B7-H3-targeted NIRF imaging with MGA271-IRDye800 provides sensitive and specific intraoperative visualization of sarcoma.
- This probe has strong potential for clinical translation to guide surgical resection and improve patient outcomes.
