Analysis of Mutational Profile of Hypopharyngeal and Laryngeal Head and Neck Squamous Cell Carcinomas Identifies KMT2C as a Potential Tumor Suppressor

KMT2 (MLL) family of methyltransferases in head and neck squamous cell carcinoma: A systematic review

BACKGROUND

The involvement of the KMT2 methyltransferase family in the pathogenesis of head and neck squamous cell carcinoma (HNSCC) remains elusive.

METHOD

This study adhered to the PRISMA guidelines, employing a search strategy in the LIVIVO, PubMed, Scopus, Embase, Web of Science, and Google Scholar databases. The methodological quality of the studies was assessed by the Joanna Briggs Institute.

RESULTS

A total of 33 studies involving 4294 individuals with HNSCC were included in this review. The most important alteration was the high mutational frequency in the KMT2C and KMT2D genes, with reported co-occurrence. The expression of the KMT2D gene exhibited considerable heterogeneity across the studies, while limited data was available for the remaining genes.

CONCLUSIONS

KMT2C and KMT2D genes seem to have tumor suppressor activities, with involvement of cell cycle inhibitors, regulating different pathways that can lead to tumor progression, disease aggressiveness, and DNA damage accumulation.

FGFR2 point mutation in 2 cases of pleomorphic adenoma progressing to myoepithelial carcinoma

Introduction

Salivary gland tumours are rare neoplasms. Pleomorphic adenoma (PA) is the most frequent benign lesion. Myoepithelial carcinoma (MECA) is rarely recognized malignancy, but the prognosis is unfavourable. The aim of this study was to identify genetic rearrangements that might be responsible for dynamic MECA progression in patients with primary radical PA excision.

Material and methods

Next-generation sequencing (NGS) of 1500 gene coding sequences was performed in primary and recurrent tumour tissue collected from 2 patients, in whom PA was initially diagnosed and within one year multifocal MECA was detected. Formalin-fixed paraffin-embedded blocks with tumour tissues were subject to NGS analysis, involving small-scale mutations, as well as focal and chromosomal arm-level copy number changes.

Results

This study showed mutations in the FGFR2 gene in PA and MECA tissues, obtained from both patients. One of them, pathogenic mutation p.Pro253Arg, was associated with sensitivity to registered drug inhibitors. Additionally, FGFR1, EGFR, and CDK4/CDK6 amplification, as well as CDKN2A/B deletion, were detected in one case. Furthermore, mutations in suppressor gene APC2 and PIK3C2A were detected, but only in MECA tissue. The analysis also identified the following chromosomal copy alterations: 4q12-q13.3, 9p21.3, 5q23.1-q34, del8p23.3-p12, and del13q21.31-q31.1.

Conclusions

Rearrangement of the FGFR2 gene, identified in primary PA and MECA ex PA samples of both our patients, may be responsible for the malignant transformation and the disease progression. Further studies are encouraged to confirm the relevance of the findings. The therapy option with FGFR2 inhibitors may be considered in advanced or metastatic MECA ex PA with confirmed FGFR2 mutations.

The current advances and future directions of PD-1/PD-L1 blockade in head and neck squamous cell carcinoma (HNSCC) in the era of immunotherapy

Immune checkpoint inhibitors (ICIs) have previously demonstrated their efficacy and safety in various solid tumors, and with the growing interest in the application of ICIs in head and neck squamous cell carcinoma (HNSCC), various data have been reported. Mechanistically, HNSCC cells express programmed death ligand 1 (PD-L1), which binds to its receptor programmed death 1 (PD-1). Immune escape plays a key role in disease initiation and progression. Studying the abnormal activation of related pathways of PD-1/PD-L1 will help to understand the way of immunotherapy and find the advantageous population of immunotherapy. How to reduce HNSCC-related mortality and morbidity in this process has promoted the search for new therapeutic strategies, especially in the era of immunotherapy. PD-1 inhibitors have demonstrated significant prolongation of survival in recurrent/metastatic (R/M) HNSCC with a favorable safety profile. It also holds great promise in locally advanced (LA) HNSCC, where numerous studies are underway. Although immunotherapy has made great progress in HNSCC research, there are still many challenges. Therefore, in the review, we conducted an in-depth study on the expression of PD-L1 and the regulatory, immunosuppressive mechanisms caused by PD-L1, especially in head and neck squamous cell carcinoma, which is different from other tumors. And further summarize the situation, challenges and development trends of PD-1 and PD-L1 blockade in clinical practice.