Abstract 2132: Next generation sequencing for screening of clinically actionable mutations in intestinal-type sinonasal adenocarcinoma

Introduction: Sinonasal ITAC is a rare tumor commonly related to occupational wood or leather dust exposure. Clinical management has improved,however, recurrences are frequent, and the overall 5-year survival rateremains poor (60%). Therefore, there is a clear need for new therapeutic options. The aim of this study was to identify genetic alterations as specific targets for personalized treatment. Experimental procedures: Next Generation Sequencing using SureSelect QXT (Ilumina) was performed on a panel of 120 genes against which drugs have been approved by the FDA. Tumor and germline DNA of 25 patients was sequenced, for one case also the recurrence and metastasis. Pools were sequenced in a MiSeq system with a minumum coverage of 500X. To select somatic and pathogenic variants, the raw sequencing data were manually curated as follows: all silent mutations and variants with allele frequency >5% were discarded, only variants with tumor frequency >10 % of readings were considered; by comparing with the germline sample, only variants that appeared exclusively in the tumor sample were selected, as well as homozygous changes in the tumor that were heterozygous in the germline. Results: Five tumors (20%) did not show any somatic alteration in the 120 genes tested.In the remaining 20 tumors, mutations were found in 33 genes. The most relevant were involved in the EGFR-PI3K-AKT-MTOR, the MAPK-ERK and the Wnt signaling pathways, indicating an important role in ITAC tumorigenesis. The most frequently affected genes were tyrosin-kinase receptors (44%), especially the ERBB family (20% of cases with mutations) and FGFR1 (20% of tumors with gene copy number amplifications). Thirty-six percent and 28% of tumors showed alterations in the MAPK-ERK and PI3K-AKT-MTOR cascades respectively. PI3K mutations were particulary frequent (7 different variants in 5 tumors.) With regard to the Wnt pathway, both APC and CTNBB1 genes appeared mutated in 3 cases. In one patient, the primary tumor, recurrence and lymph node metastasis were investigated. All somatic alterations observed in the primary tumor (mutations in ATM, BRC2, KMT2B and amplifications of MET, ATM and FGF1R) remained present in both recurrence and metastasis, excluding the possibility of a second primary tumor. Additional mutations in the recurrence (NTRK1, TSC2 and PIK3R2) were also seen in the metastasis, while no alterations occurred in the metastasis exclusively. Confirmatory studies are underway correlating the mo