A fibroblast activation protein targeted optical tracer for identifying primary and metastatic sarcoma during resection
Abstract Background Sarcomas represent a heterogeneous group of mesenchymal tumors that, despite accounting for only 1% of cancers worldwide, rank among the top five causes of cancer-related deaths in patients under 20 years old. Surgical resection remains the primary treatment for these malignancie...
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| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
SpringerOpen
2025-07-01
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| Series: | EJNMMI Research |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s13550-025-01289-5 |
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| Summary: | Abstract Background Sarcomas represent a heterogeneous group of mesenchymal tumors that, despite accounting for only 1% of cancers worldwide, rank among the top five causes of cancer-related deaths in patients under 20 years old. Surgical resection remains the primary treatment for these malignancies, as effective systemic therapies are limited, particularly for high-grade disease. However, surgical outcomes are often compromised by incomplete resection, leading to high local and distal recurrence rates. Intraoperative molecular imaging has emerged as a promising approach to improve surgical outcomes but has been hindered by the lack of tumor-specific targeting agents. Fibroblast activation protein (FAP), selectively expressed by mesenchymal tumors and absent in healthy tissues, presents a promising target for fluorescence-guided cancer resections. Results We demonstrate that 41% of human sarcomas express FAP, with expression correlating with higher histologic grade. The FAP-S0456 optical tracer specifically bound to FAP-expressing sarcomas with minimal binding to normal tissues, exhibiting excellent tumor-to-background ratios (3.8 ± 0.43). In vitro studies confirmed FAP-S0456’s specificity for human FAP with a dissociation constant of approximately 10 nM. In murine xenograft models, the tracer accurately identified both primary tumors and pulmonary metastases of FAP-expressing sarcomas. Importantly, using needle confocal laser endomicroscopy, we demonstrated that FAP-S0456 enables real-time, single-cell visualization of metastatic tumor cells during surgery, including micrometastases not detected by conventional imaging. Conclusions FAP-S0456 represents a promising molecular imaging agent for the detection and surgical removal of primary and metastatic sarcomas. Its high specificity for FAP-expressing tumor cells, favorable biodistribution profile, and ability to detect microscopic disease offer potential to improve complete surgical resection. These findings support the development of FAP-targeted fluorescence-guided surgery for sarcoma patients, which may lead to improved oncologic outcomes, particularly for those with pulmonary metastases where complete surgical clearance is critical for survival. |
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| ISSN: | 2191-219X |