PIK3CA and head and neck squamous cell carcinoma: Of the 15 most recurrently mutated genes in ≥10% of HNSCC or GB-SCC tumours as reported in the TCGA and ICGC database (TP53, FAT1, CASP8, NOTCH1, KMT2B, PCLO, UNC13C, SMG1, FAT3, EP300, KMT2D, SYNE2, TRPM3, PIK3CA and NSD1), 12 were mutated in one or more of the ITOC cell lines (Fig. 5A,B and Supplementary Table S5).