Molecular profile of advanced thyroid carcinomas by next-generation sequencing: Characterizing tumors beyond diagnosis for targeted therapy

Next-generation sequencing (NGS) for molecular diagnostics allows simultaneous testing of activating oncogenes and tumor suppressor mutations in multiple signal pathways. Extended mutational profiling of advanced thyroid cancers may enhance considerations for targeted therapies. We analyzed clinically derived molecular profiling of 216 patients with advanced thyroid carcinoma using NGS (Ion Torrent Personal Genome Machine) from April 2012 to February 2014. We examined substitutions and small indels in 46 or 50 cancer-related genes using Ampliseq Cancer Hotspot panel in respect to tumor diagnosis and clinical correlations. Mutations were common in advanced thyroid carcinomas 154 (71%) predominately in targetable MAPK pathway (146/216, 68%), and several PI3K/AKT pathway (8, 4%; six as comutations). BRAF V600E mutation associated with papillary (94/139, 68%), poorly differentiated (4/39, 10%), and anaplastic (3/12, 25%) carcinomas. NRAS mutations occurred in follicular (5/12, 42%) and poorly differentiated thyroid carcinoma (12/39, 31%). Tumor suppressor mutations (16, 7%) occurred predominantly in TP53 in Hurthle cell (2/5, 40%, the only mutation), in anaplastic (3/12, 25%) and poorly differentiated thyroid carcinoma (4/39, 10%) some as comutations and in papillary thyroid carcinoma (5/139, 4%) always a comutation. Kaplan-Meier analysis of patients with poorly differentiated thyroid carcinoma containing activating mutations who received targeted therapeutics showed improved survival compared to similarly treated patients without mutations in targetable pathways (P = 0.02). In conclusion, MAPK pathway is the predominant target for therapy in advance thyroid carcinomas; adding NGS enables the identification of comutations associated with resistance (PI3K/AKT). Within poorly differentiated thyroid carcinoma, the molecular profile may hold prognostic value in the era of targeted therapy.