Comprehensive genomic analysis of salivary gland carcinomas in a Chinese population

e18094 Background: Salivary gland carcinomas (SGCs) represent a heterogeneous group of poorly characterized head and neck tumors, which are rare and challenging to treat. A strategy based on molecular screening and targeted therapy seems to be the best approach for treating patients with SGCs in the future, whereas the genomic mechanisms of SGCs are largely unclear. Methods: A total of 49 patients with histologically confirmed SGCs, including mucoepidermoid carcinoma (MEC, n = 10), adenoid cystic carcinoma (ACC, n = 20), carcinoma ex pleomorphic adenoma (cxPA, n = 10) and other pathological types (n = 9) were enrolled in our study. Tumor tissue specimens were collected and targeted next-generation sequencing for 450 cancer-related genes was performed in OrigiMed (Shanghai, China), a College of American Pathologists (CAP) accredited and Clinical Laboratory Improvement Amendments (CLIA) certified laboratory. Results: In all samples, the most frequently mutated genes were MYB (26.53%), TP53 (26.53%), ERBB2 (12.24%), KMT2D (12.24%), and TERT (12.24%). Actionable genes included ERBB2 (12.2%), PIK3CA (8.2%), ATM (4.1%), CDKN2A/B (4.1%), and EGFR (4.1%). Among these patients, female patients accounted for a higher proportion in ACC compared to that in MEC and cxPA (ACC: 65%, MEC: 30%, cxPA: 30%). Gene fusions/rearrangements were identified in 13 tumors, and 10 (76.9%) had evidence of MYB-NFIB fusion, which may represent an important new therapeutic target for ACC. Higher frequency of MYB (p < 0.0001) and EP300 (p = 0.0445) mutations was also identified in ACC compared with that in other types. Mutational frequencies of TP53 (p = 0.0096) and ERBB2 (p = 0.0228) were obviously higher in cxPA, whereas the frequency of CCNE1 (p = 0.0433) mutations were significantly higher in MEC compared with those in other types. The gene mutations of Chinese SGCs were mainly enriched in RTK/RAS (56.7%), TP53 (40.8%), Notch (34.5%), and PI3K (30.5%) signaling pathways. Conclusions: This report revealed the molecular characteristics of Chinese SGC patients diagnosed with different pathological types, which would be helpful for the investigation of the underlying genomic mechanisms of SGC. Our result highlights the potential role of gene alterations, many of which could conceivably be actionable with targeted therapies.