PIK3CA mutations in cutaneous squamous cell carcinoma.

Oncogenic mutation activates phosphoinositide 3-kinase (PI3K) enzyme, and PI3K-AKT signaling activation induces several growth-regulatory transcription factors. mutations have attracted attention as biomarker in clinical trials of various inhibitors including PI3K inhibitors. About 80% of mutations in human cancers are observed in 'hot spot' regions: exon 9 (E542K and E545K) and exon 20 (H1047R). There were few reports about clinical significance of mutations in cutaneous cell carcinoma (cSCC). Thus, we investigate the prevalence of three hot spot mutations in 143 cases with cSCC and evaluate the correlation between the presence of these mutations and clinical characteristics by using ddPCR. The frequency of each E542K, E545K and H1047R PIK3CA mutations was 1.4% (2/143), 2.8% (4/143), and 0.7% (1/143) respectively. No significant correlation was found between mutations and clinical characteristics. Although additional basic researches and clinical trials are necessary, various inhibitors may be effective therapeutics for mutation-positive cSCC. Our study revealed the prevalence of mutations in cSCC.