Abstract 3190: Genomic profiling of salivary gland tumors identifies novel and targetable alterations

Abstract

Abstract Background Salivary gland neoplasms represent a heterogeneous group of benign and malignant tumors that comprise 6% of all head and neck cancers. Due to their low incidence, these tumors are poorly understood and remain a diagnostic and therapeutic challenge. Methods Out of 182 analyzed salivary gland tumors with various histologies, eight were positive for ALK immunohistochemistry. The cut-off was 15% positive cells in either membranous, nuclear or cytoplasmic compartments. The ALK positive tumors were first subjected to FISH analysis. Subsequently, these tumors were analyzed using hybrid capture based next generation sequencing to confirm possible ALK gene fusions or copy number alterations, and to detect additional genomic alterations of clinical relevance. Results An in-depth genomic analysis of the samples resulted in the detection of inactivating mutations in BRAF (p.D594N) and TP53 (p.C238S), as well as amplifications of ERBB2 and ALK. Strikingly, a novel MYO18A (Exon1-40)-ALK (exon 20-29) gene fusion was detected in a patient with adenocarcinoma not otherwise specified. This tumor was FISH positive and 100% of cells showed strong membranous staining for ALK. MYO18A (Exon1-40)-ALK (exon 20-29) gene fusion resulted in the retention of the kinase domain of ALK and the coiled-coil domain of MYO18A. Similarly to other ALK fusions, we hypothesize that the coiled-coil domain of MYO18A mediates the dimerization and activation of MYO18A-ALK, thereby resulting in an overexpression of constantly activated ALK. Conclusion Using hybrid capture based next generation sequencing, we identified in salivary gland tumors numerous genomic alterations in therapeutically relevant genes and a novel gene fusion (MYO18A-ALK). Patients harboring this fusion may potentially benefit from treatment with ALK inhibitors. Citation Format: Hanna Majewska, Judith Müller, Sotirios Lakis, Piotr Czapiewski, Adam Gorczyński, Mariola Iliszko, Alena Skalova, Rafal Dziadziuszko, Jacek Jassem, Wojciech Biernat, Roopika Menon, Johannes M. Heuckmann, Lukas C. Heukamp. Genomic profiling of salivary gland tumors identifies novel and targetable alterations. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3190.