[68Ga]Ga-FAPI-46 PET/CT in Early Detection of Lymph Node Metastasis in Head and Neck Squamous Cell Carcinomas

The trial focuses on assessing the role of [68Ga]Ga-FAPI-46 in head and neck squamous cell carcinomas (HNSCC) staging before surgery. In the context of metastasis, cancer-associated fibroblasts (CAFs) emerge as pivotal contributors to the creation of a microenvironment conducive to future metastases. CAFs exert their influence through intricate mechanisms, including the remodeling of the extracellular matrix by secreting proteins such as collagen and fibronectin. This process enhances the structural support for cancer cell invasion into adjacent tissues. Additionally, CAFs play a central role in promoting angiogenesis, ensuring an adequate blood supply to the tumor, which may also facilitate the entry of cancer cells into the bloodstream. Through modulation of immune responses within the tumor microenvironment, CAFs establish an immunosuppressive milieu, providing a permissive environment for cancer cell survival and dissemination. Collectively, the orchestrated activities of CAFs contribute to the preparation of a metastatic niche, influencing the microenvironment at both primary and secondary sites and enhancing the likelihood of successful metastasis.

Employing [68Ga]Ga-FAPI-46 PET/CT imaging to target activated CAFs may hold the potential to discern lymph nodes (LNs) predisposed to future metastases in HNSCC. The use of this imaging modality offers a unique opportunity to visualize and assess the presence and activity of CAFs within the tumor microenvironment. By targeting the fibroblast activation protein (FAP), a receptor enriched on CAFs, this imaging approach provides a specific and sensitive mean to identify regions where the microenvironment may favor metastatic progression.

In this research endeavor, the primary objective is to highlight the additional value of [68Ga]Ga-FAPI-46 PET/CT into the standard pre-surgical imaging protocol. Additionally, the study will evaluate the efficacy of FAP positon emission tomography (PET) in primary tumor delineation. Imaging based on [68Ga]Ga-FAPI-46 allows the identification of CAFs, specifically by exploiting their increased FAP expression. The study aims also to systematically compare the [68Ga]Ga-FAPI-46 PET/CT signals with the characteristics of resected lymph nodes, seeking to ascertain the capability of FAPI PET imaging in identifying premetastatic conditions. By comparing the [68Ga]Ga-FAPI-46 PET signal and the histopathological features of resected lymph nodes, the goal is to validate the potential of [68Ga]Ga-FAPI-46 PET imaging as a tool for early detection of premalignant or metastatic conditions in the lymphatic system before surgical intervention. The ability to pinpoint lymph nodes at risk for future metastases could revolutionize clinical decision-making, by facilitating a more nuanced understanding of disease spread, thereby informing personalized treatment strategies and potentially improving patient outcomes.