Genomic findings underscore the heterogeneity of head and neck squamous cell carcinoma (HNSCC)(1, 2). Identification of mutations that predict therapeutic response would be a major advance. We determined the mutationally altered, targetable mitogenic pathways in a large HNSCC cohort. Analysis of whole-exome sequencing data from 151 tumors revealed the PI3K pathway to be the most frequently mutated oncogenic pathway (30.5%). PI3K pathway-mutated HNSCC tumors harbored a significantly higher rate of mutations in known cancer genes. In a subset of HPV-positive tumors, PIK3CA or PIK3R1 was the only mutated cancer gene. Strikingly, all tumors with concurrent mutation of multiple PI3K pathway genes were advanced (stage IV), implicating concerted PI3K pathway aberrations in HNSCC progression. Patient-derived tumorgrafts with canonical and non-canonical PIK3CA mutations were sensitive to an m-TOR/PI3K inhibitor (BEZ-235) in contrast to PIK3CA wildtype tumorgrafts. These results suggest that PI3K pathway mutations may serve as predictive biomarkers for treatment selection.

We conducted a genome-wide association study of oral cavity and pharyngeal cancer in 6,034 cases and 6,585 controls from Europe, North America and South America; we detected 8 loci (P<5x10–8), 7 of which are novel for these cancer sites. Oral and pharyngeal cancers combined were associated with loci at 6p21.32 (rs3828805, HLA-DQB1), 10q26.13 (rs201982221, LHPP) and 11p15.4 (rs1453414, OR52N2/TRIM5). Oral cancer was associated with two new regions 2p23.3 (rs6547741, GPN1) and 9q34.12 (rs928674, LAMC3), and with known cancer loci: 9p21.3 (rs8181047, CDKN2B-AS1) and 5p15.33 (rs10462706, CLPTM1L). Oropharyngeal cancer associations were limited to the human leukocyte antigen (HLA) region and classical HLA allele imputation revealed a protective association with the class II haplotype DRB1*1301-DQA1*0103-DQB1*0603 (odds ratio (OR)=0.59, P=2.7x10–9). Stratified analyses on a subgroup of oropharyngeal cases with human papillomavirus (HPV) status indicated that this association was considerably stronger in HPV-positive (OR=0.23, P=1.6x10–6) compared to HPV-negative cancers (OR=0.75, P=0.16).