Investigating EGFR, BRAF, and RAS Mutations in Oral and Cutaneous Squamous Cell Neoplasms: A Preliminary Report on Romanian Patients

Background: Head and neck cancers, and particularly, oral cancers have a complex pathogenesis that includes genetic mutations and epigenetic alterations which interfere with cellular signaling and can trigger tumor development. The purpose of this study was to reveal whether low-frequency hotspot mutations may be detected in a study lot with histopathological evidence of squamous cell carcinoma (SCC) of the oral mucosa and skin of the head and neck. Methods: Tumor biopsies from treatment- naïve patients were tested for BRAF V600, NRAS G12/G13, NRAS Q61, KRAS Q61 mutations, and EGFR exon 19 deletions (Ex19Del) using droplet digital PCR (ddPCR). The tumors were also analyzed for EGFR T790M mutations by RT-PCR, using a CE-IVD validated kit, with a limit of detection of 0.05%. Results: None of the examined cases exhibited NRAS G12/G13, NRAS Q61, KRAS Q61, BRAF V600, or EGFR T790M mutations, indicating that these alterations are rare events in SCC pathogenesis. Interestingly, among the 12 specimens tested by ddPCR for EGFR Ex19Del, an HPV-negative cSCC tumor occurring in the parotid region tested positive for this drug-sensitizing mutation, offering unexplored therapeutic perspectives to the patient from whom it was collected. Conclusions: Our study highlights the important clinical implications of detecting low-frequency hotspot mutations in tumor biopsies by ddPCR. We believe that the ddPCR-assisted analysis of these mutations in larger SCC cohorts may provide us with mechanistic insights regarding their role in SCC pathogenesis and guide the development of novel therapeutic strategies for this problematic disease.