FAP is a prognostic marker, but not a viable therapeutic target for clinical translation in HNSCC

Modulating tumor-associated macrophages through CSF1R inhibition: a potential therapeutic strategy for HNSCC

PURPOSE

Tumor-associated macrophages (TAMs) are pivotal immune cells within the tumor microenvironment (TME), exhibiting dual roles across various cancer types. Depending on the context, TAMs can either suppress tumor progression and weaken drug sensitivity or facilitate tumor growth and drive therapeutic resistance. This study explores whether targeting TAMs can suppress the progression of head and neck squamous cell carcinoma (HNSCC) and improve the efficacy of chemotherapy.

METHODS

Bioinformatics analyses were performed to evaluate TAMs infiltration levels in HNSCC tumor tissues and examine their associations with patients' clinicopathological characteristics and prognosis. Flow cytometry was utilized to measure the expression of key macrophage markers and assess apoptosis following treatment with colony stimulating factor 1 receptor (CSF1R) inhibitors (BLZ945, PLX3397). Additionally, immunohistochemistry was employed to detect CD68 and CD8 expression. In vivo, the antitumor efficacy of CSF1R inhibitors was tested in mouse HNSCC tumor model, both as monotherapy and in combination with cisplatin, to evaluate potential synergistic effects.

RESULTS

Bioinformatic analysis identified TAMs as the predominant infiltrating immune cells in the TME of HNSCC, with significantly higher infiltration levels in tumor tissues compared to adjacent non-tumor tissues. High TAMs infiltration was associated with poorer overall survival (OS), disease-free survival (DFS), human papillomavirus (HPV) infection status, and advanced disease stages. The TAMs-related genes prediction model demonstrated high prognostic accuracy. CSF1R is primarily expressed in TAMs, where high CSF1R expression may suppress antigen binding and activation. In vitro experiments showed that CSF1R inhibitors induce TAMs apoptosis, enhance their phagocytic activity, and reduce CD206 expression and IL-10 secretion, thereby diminishing their immunosuppressive function. In vivo experiments revealed that while CSF1R inhibitors alone had limited efficacy in suppressing tumor growth, their combination with cisplatin significantly enhanced therapeutic efficacy, as evidenced by increased CD8+ T cells infiltration within the TME.

CONCLUSION

Targeting TAMs via CSF1R inhibition enhances the therapeutic efficacy of cisplatin in HNSCC. These findings suggest that CSF1R inhibitors hold promise as a component of combination therapy for HNSCC.

Current status of FAP-directed cancer theranostics: a bibliometric analysis

Fibroblast activation protein (FAP) is a key molecule in the field of oncology, with significant impacts on tumor diagnosis and treatment. Importantly, it has paved the way for the development of radiotracers for quinoline-based FAP inhibitors (FAPIs), which are currently among the most promising radiotracers for PET imaging in cancer. We performed a bibliometric analysis of scientific publications related to FAP and FAPI-based radiotracers, which included the quantification and visualization of current research trends and prospects based on various bibliometric indicators. In our survey of FAP-related studies in the Web of Science Core Collection databases, R and VOSviewer were used for visualization and bibliometric analyses based on country, institute, author, journal, and keywords. We also examined the methodology, radionuclide type, imaging instruments, and major diseases associated with studies on FAPI-based radiotracers. The results revealed 2,664 FAP-related publications from 1992 to the present. Germany, the USA, and China dominated paper publications, multinational collaborations, and societal impacts on FAP research. Southwest Medical University was the most productive institute, while Haberkorn Uwe authored the most cited papers and the highest H-index. The European Journal of Nuclear Medicine and Molecular Imaging and the Journal of Nuclear Medicine were the most influential periodicals. Keywords "FAP", "68Ga-FAPI", and "PET/CT" emerged as the most significant in this field. This study may help elucidate current research trends, hotspots, and directions for future research.

Matrix-based molecular mechanisms, targeting and diagnostics in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a head and neck cancer (HNC) with a high mortality rate. OSCC is developed in the oral cavity and it is triggered by many etiologic factors and can metastasize both regionally and distantly. Recent research advances in OSCC improved our understanding on the molecular mechanisms involved in and the initiation of OSCC metastasis. The key roles of the extracellular matrix (ECM) in OSCC are an emerging area of intensive research as the ECM macromolecular network is actively involved in events that regulate cellular morphological and functional properties, transcription and cell signaling mechanisms in invasion and metastasis. The provisional matrix that is formed by cancer cells is profoundly different in composition and functions as compared with the matrix of normal tissue. Fibroblasts are mainly responsible for matrix production and remodeling, but in cancer, the tumor matrix in the tumor microenvironment (TME) also originates from cancer cells. Even though extensive research has been conducted on the role of ECM in regulating cancer pathogenesis, its role in modulating OSCC is less elucidated since there are several issues yet to be fully understood. This critical review is focused on recent research as to present and discuss on the involvement of ECM macromolecular effectors (i.e., proteoglycans, integrins, matrix metalloproteinases) in OSCC development and progression.