GISts MUTATION PROFILING

Clin Gastroenterol Hepatol. 2014 Jul 3. pii: S1542-3565(14)00931-8. doi: 10.1016/j.cgh.2014.06.024. [Epub ahead of print]

Kinase Genotype Analysis of Gastric Gastrointestinal Stromal Tumor Cytology Samples Using Targeted Next-Generation Sequencing.

Gleeson FC1, Kipp BR2, Kerr SE2, Voss JS2, Graham RP2, Campion MB2, Minot DM2, Tu ZJ3, Klee EW3, Lazaridis KN4, Henry MR2, Levy MJ5.

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Abstract

Gastric gastrointestinal stromal tumors (GISTs) usually contain the mast/stem cell growth factor receptor Kit gene (KIT) or platelet-derived growth factor receptor A (PDGFRA) mutations that can be targeted by, or mediate resistance to, imatinib. Diagnostic material often is obtained by endoscopic ultrasound-guided fine-needle aspiration, which often is unsuitable for molecular analysis. We investigated whether targeted next-generation sequencing (NGS) can be used in multiplex genotype analysis of cytology samples collected by endoscopic ultrasound-guided fine-needle aspiration. We used the Ion AmpliSeq V2 Cancer Hotspot NGS Panel (Life Technologies, Carlsbad, CA) to identify mutations in more than 2800 exons from 50 cancer-associated genes in GIST samples from 20 patients. We identified KIT mutations in 58% of samples (91% in exon 11 and 9% in exon 17) and PDGFRA mutations in 26% (60% in exon 18 and 40% in exon 12); 16% of samples had no mutations in KIT or PDGFRA. No pathogenic alterations were found in PIK3CA, BRAF, KRAS, NRAS, or FGFR3. We predicted that 32% of patients would have primary resistance to imatinib, based on mutations in exon 17 of KIT, exon 18 of PDGFRA (D842V), or no mutation in either gene. Targeted NGS of cytology samples from GISTs is feasible and provides clinically relevant data about kinase genotypes that can help guide individualized therapy.