<p>Recurrence and/or metastasis occur in more than half of patients with head and neck squamous cell carcinoma (HNSCC) and pose the greatest threats to long-term survival. The genetic alterations underlying recurrent/metastatic HNSCC are unknown. This study represents the first whole exome sequencing (WES) cohort study of patient-matched tumor pairs in recurrent or metastatic HNSCC. Synchronous lymph node metastases are genetically more similar to their paired index primary tumors than metachronous recurrent tumors are. Newly arisen mutations in recurrent or metastatic tumors, may have therapeutic implications. Several genes were found to be mutated in multiple metastatic or recurrent tumors, but not in their respective primaries, including C17orf104, ITPR3, and DDR2. DDR2 mutations have been shown to confer enhanced sensitivity to Src-family kinase (SFK) inhibitors in other malignancies. Similarly, we found HNSCC cell lines harboring endogenous and engineered DDR2 mutations to be more sensitive to the SFK inhibitor dasatinib, than those with WT DDR2. This study outlines the first compendium of somatic mutations in primary, metastatic and/or recurrent HNSCC cancers that arise in individual patients; and demonstrates how such data can be used to interrogate potential predictive/prognostic biomarkers to inform and guide personalized therapy.</p>

The Genetic Landscape of Metastasis and Recurrence in HNSCC