Genomic landscape and tumor mutation burden analysis of Chinese patients with sarcomatoid carcinoma of the head and neck

Abstract

Background: Sarcomatoid carcinoma (SC) of the head and neck (HN) is a rare disease that has both sarcomatoid and cancerous components. The genetic background and mechanisms of tumorigenesis remain largely unrevealed, and the progress of precision therapy has been limited.

Methods: Targeted DNA-based next-generation sequencing (NGS) was performed by a 539 genes panel of pan-cancer in 12 patients with SC of the HN to identify their genetic alterations and investigate clinically actionable mutations for use in precision treatment.

Results: TP53 was identified as the most frequently mutated gene. Genes related to the cell cycling, chromatin remodeling and histone modification were found to be frequently mutated in patients with SC of the HN. Alterations in receptor tyrosine kinases (RTKs) were also found in six patients. In addition, four patients had mutations in members of the downstream RAS and PI3-kinase pathways, PIK3CA was identified as the most frequently mutated gene in this pathway. The tumor mutation burden (TMB) value ranged from 0.71 to 14.71 per megabase, with a median of 4.34. The TMB value of PIK3CA mutation patients was significantly higher than that of PIK3CA wild-type patients.

Conclusions: This was the first study to investigate genomic alterations specifically in Chinese patients with SC of the HN. Our research results showed that 10 out of 12 patients can match the targeted therapies or immunotherapy currently available in clinical practice or active clinical trials, suggesting precision therapy has the potential utility to improve the long-term prognosis for patients with the rare disease. Due to the small number of patients in this study, the findings need to be validated in a larger cohort.

Keywords: Mutational landscape; Next-generation sequencing; Sarcomatoid carcinoma of the head and neck; Targeted therapy; Tumor mutation burden.