Orla Sheils
The University of Dublin, Ireland
Title: Next generation sequencing of thyroid neoplasms to determine mutational status
Biography
Biography: Orla Sheils
Abstract
The prognosis for patients with thyroid carcinoma is generally dependent on age and tumour stage at time of diagnosis. Nonetheless, the biological aggressiveness of individual tumours cannot always be predicted from the initial clinical features, making it difficult consistently to identify patients who will die from their disease. Moreover, the occurrence of non-specific lymphocytic thyroiditis of varying severity adjacent to thyroid tumours is frequently observed. Risk factors for the development of thyroid cancer include radiation exposure, somatic and germline genetic mutations. Common mutations that precede the development of thyroid carcinoma target the mitogen-activated protein kinase (MAPK pathway) and include BRAF, RET/PTC and RAS. We employed a NGS sequencing approach for parallel interrogation of the presence of somatic mutations in samples from 82 patients. We hypothesised this approach might have utility as an adjunct diagnostic in tissue and FNA analyses and in understanding the molecular patho-biological processes in carcinogenic progression. Adopting a null hypothesis approach, we used the oncomine comprehensive assay and Ion PGMâ„¢ semi-conductor sequencing technology to analyze hundreds of the most referenced oncology biomarkers including hotspot mutations, CNVs, gene fusions and indels. The method involved multiplex PCR requiring 10 ng of input DNA. The most commonly detected mutations involved: DDR2, NRAS, PI3KCA, MET, ERBB2, FGFR3, MET, STK11, EGFR, BRAF and TP53. The number of somatic variants per sample was higher among FTC (mean=28.2, Median=9) than PTC (mean =9.9, median = 6). In addition, we detected the SQSTM1-NTRK1 fusion transcript in RNA from 2 PTC samples. The number of predictive biomarkers that are assessed in clinical practice is rapidly increasing with the availability of drugs that target specific molecular alterations. NGS has the advantage of providing information on known and novel molecular alterations and multiple genes can be sequenced simultaneously in the clinical laboratory setting. This study identified significant pathological mutations among PTC and FTC DNA and RNA samples that may have potential diagnostic and therapeutic implications.