Kinase genotype analysis of gastric gastrointestinal stromal tumor cytology samples using targeted next-generation sequencing.

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.

Frequency of mitogen-activated protein kinase and phosphoinositide 3-kinase signaling pathway pathogenic alterations in EUS-FNA sampled malignant lymph nodes in rectal cancer with theranostic potential.

BACKGROUND: Targeted next-generation sequencing has the potential to stratify a tumor by molecular subtype and aid the development of a biomarker profile for prognostic risk stratification and theranostic potential. OBJECTIVE: To assess the frequency and distribution of pathogenic alterations in malignant lymph node cytology specimens. DESIGN: Multigene molecular profiling of archived malignant EUS-FNA lymph node cytology specimens using the Ion Ampliseq Cancer Hotspot Panel v2, which targets at least 2855 possible mutations within 50 cancer-associated genes. SETTING: Single tertiary referral center. PATIENTS: Sporadic, treatment naive, locally advanced primary rectal cancer by EUS-FNA (n = 76) who subsequently completed neoadjuvant therapy with on-site oncologic surgery. MAIN OUTCOME MEASUREMENTS: The frequency and distribution of pathogenic alterations in malignant lymph node cytology specimens by the mitogen-activated protein kinase (MAPK) or phosphoinositide 3-kinase (PI3K) signaling pathways, by KRAS or NRAS wild-type lymph node status, by extramesenteric lymph node status, and by a complete pathologic response status. RESULTS: Eleven patients (14.5%) were 50-gene panel wild-type. Sixty-five patients had 139 pathogenic alterations (2 [1-3] per patient) in 13 of 50 evaluated genes. The following represent a spectrum of identified alterations: TP53 (n = 52; 68.4%), APC (n = 36; 47.4%), KRAS (n = 22; 28.9%), FBXW7 (n = 8; 10.5%), NRAS (n = 6; 7.9%), PIK3CA (n = 4; 5.3%), SMAD4 (n = 3; 3.9%), and BRAF (n = 3; 3.9%). Pathogenic alterations were identified in the MAPK and PI3K signaling pathways in 41% and 5% of patients, respectively. LIMITATIONS: Findings were limited to a 50 cancer-associated gene analysis. CONCLUSIONS: Molecular EUS lymph node assessments using cancer "hotspot" panels can identify pathogenic alteration frequency and distribution and have theranostic potential for individualized patient care.

Primary transcriptomes of Mycobacterium avium subsp. paratuberculosis reveal proprietary pathways in tissue and macrophages.

BACKGROUND: Mycobacterium avium subsp. paratuberculosis (MAP) persistently infects intestines and mesenteric lymph nodes leading to a prolonged subclinical disease. The MAP genome sequence was published in 2005, yet its transcriptional organization in natural infection is unknown. While prior research analyzed regulated gene sets utilizing defined, in vitro stress related or advanced surgical methods with various animal species, we investigated the intracellular lifestyle of MAP in the intestines and lymph nodes to understand the MAP pathways that function to govern this persistence. RESULTS: Our transcriptional analysis shows that 21%, 8% and 3% of the entire MAP genome was represented either inside tissues, macrophages or both, respectively. Transcripts belonging to latency and cell envelope biogenesis were upregulated in the intestinal tissues whereas those belonging to intracellular trafficking and secretion were upregulated inside the macrophages. Transcriptomes of natural infection and in vitro macrophage infection shared genes involved in transcription and inorganic ion transport and metabolism. MAP specific genes within large sequence polymorphisms of ancestral M. avium complex were downregulated exclusively in natural infection. CONCLUSIONS: We have unveiled common and unique MAP pathways associated with persistence, cell wall biogenesis and virulence in naturally infected cow intestines, lymph nodes and in vitro infected macrophages. This dichotomy also suggests that in vitro macrophage models may be insufficient in providing accurate information on the events that transpire during natural infection. This is the first report to examine the primary transcriptome of MAP at the local infection site (i.e. intestinal tissue). Regulatory pathways that govern the lifecycle of MAP appear to be specified by tissue and cell type. While tissues show a "shut-down" of major MAP metabolic genes, infected macrophages upregulate several MAP specific genes along with a putative pathogenicity island responsible for iron acquisition. Many of these regulatory pathways rely on the advanced interplay of host and pathogen and in order to decipher their message, an interactome must be established using a systems biology approach. Identified MAP pathways place current research into direct alignment in meeting the future challenge of creating a MAP-host interactome.

Transcriptional analysis of diverse strains Mycobacterium avium subspecies paratuberculosis in primary bovine monocyte derived macrophages.

In this study we analyzed the macrophage-induced gene expression of three diverse genotypes of Mycobacterium avium subsp. paratuberculosis (MAP). Using selective capture of transcribed sequences (SCOTS) on three genotypically diverse MAP isolates from cattle, human, and sheep exposed to primary bovine monocyte derived macrophages for 48 h and 120 h we created and sequenced six cDNA libraries. Sequence annotations revealed that the cattle isolate up-regulated 27 and 241 genes; the human isolate up-regulated 22 and 53 genes, and the sheep isolate up-regulated 35 and 358 genes, at the two time points respectively. Thirteen to thirty-three percent of the genes identified did not have any annotated function. Despite variations in the genes identified, the patterns of expression fell into overlapping cellular functions as inferred by pathway analysis. For example, 10-12% of the genes expressed by all three strains at each time point were associated with cell-wall biosynthesis. All three strains of MAP studied up-regulated genes in pathways that combat oxidative stress, metabolic and nutritional starvation, and cell survival. Taken together, this comparative transcriptional analysis suggests that diverse MAP genotypes respond with similar modus operandi for survival in the host.

Somatic STK11 and concomitant STK11/KRAS mutational frequency in stage IV lung adenocarcinoma adrenal metastases.

Somatic serine/threonine kinase 11 (STK11) also known as liver kinase B1 (LKB1) is a tumor suppressor gene and ranks as the third most frequently mutated gene in lung adenocarcinoma. However, current molecular testing guidelines recommend evaluating for epidermal growth factor receptor mutations and ALK fusions to guide therapy in all patients with advanced stage adenocarcinoma, regardless of gender, race, or smoking history. Identifying alternative "driver" mutations and using actionable targeted pharmacotherapy is a key approach to providing effective individualized medical care. The analytical sensitivity and parallel multigene approach of targeted next-generation sequencing is an attractive methodology for use for cytology specimens. The presented lung adenocarcinoma study revealed that STK11 mutations alone and concomitant KRAS/STK11 mutations were identified in 18.2% and 4.5% of solitary adrenal metastases, respectively. Molecular profiling of epidermal growth factor receptor tyrosine kinase inhibitor resistant tumors may help to identify patients who would most benefit from alternative single or dual pathway inhibition potentially leading to a revision in current molecular testing guidelines.

Endoscopic ultrasound fine-needle aspiration cytology mutation profiling using targeted next-generation sequencing: personalized care for rectal cancer.

OBJECTIVES: In an era of precision medicine, our aim was to determine the frequency and theranostic potential of mutations identified in malignant lymph nodes (LNs) sampled by endoscopic ultrasound fine-needle aspiration (EUS FNA) of patients with rectal cancer by targeted next-generation sequencing (NGS). METHODS: The NGS Ion AmpliSeq Cancer Hotspot Panel v2 (Life Technologies, Carlsbad, CA) and MiSeq (Illumina, San Diego, CA) sequencers were used to sequence and assess for 2,800 or more possible mutations in 50 established cancer-associated genes. RESULTS: Among 102 patients, 89% had 194 pathogenic alterations identified in 19 genes. The identification of KRAS, NRAS, or BRAF mutations suggests that 42% are likely nonresponders to anti-epidermal growth factor receptor therapy. Among KRAS, NRAS, or BRAF wild-type patients, alterations in eight genes linked to alternative therapies were identified in 44%. CONCLUSIONS: Our data demonstrate the successful ability to apply a single multiplex test to allow multigene mutation detection from malignant LN cytology specimen DNA collected by EUS FNA.

Lung cancer adrenal gland metastasis: Optimal fine-needle aspirate and touch preparation smear cellularity characteristics for successful theranostic next-generation sequencing.

BACKGROUND: Multigene molecular testing to guide personalized therapy for oncology patients is of increasing clinical relevance. Molecular testing of fine-needle aspiration samples is underused, but when acquired with minimally invasive techniques could become the standard of care to obtain theranostic specimens. The aims of the current study were to identify key cytology specimen selection criteria suitable for next-generation sequencing (NGS) and to determine the prevalence and spectrum of pathogenic alterations in a cohort of patients with AJCC stage IV lung cancer. METHODS: A total of 70 adrenal gland cytology specimens with direct smears were screened to identify 56 patients with a single slide containing at least 300 total cells and 20% tumor nuclei. After DNA extraction, the NGS protocols were used to simultaneously detect mutations in >2800 exonic regions in 50 key cancer genes. RESULTS: A total of 28 specimens produced acceptable NGS results. Specimens with a combined critical cell mass (>5000 viable cells) and a DNA concentration >5 ng/µL resulted in a 95% chance of successful sequencing. A total of 37 pathogenic alterations were identified in 10 genes and in 25 patients (85%). A pathogenic alteration (≥1) linked to available or developing targeted therapies was revealed in 50% of cases. CONCLUSIONS: The data from the current study demonstrate that theranostic NGS can be applied to adrenal gland metastasis using routine cytologic smear specimens. The characteristics of such smears could be evaluated during onsite adequacy assessment by cytopathology professionals. This model greatly augments the opportunity for customized genotype-directed therapy from minimally invasive techniques.

Implications of pyrosequencing error correction for biological data interpretation.

There has been a rapid proliferation of approaches for processing and manipulating second generation DNA sequence data. However, users are often left with uncertainties about how the choice of processing methods may impact biological interpretation of data. In this report, we probe differences in output between two different processing pipelines: a de-noising approach using the AmpliconNoise algorithm for error correction, and a standard approach using quality filtering and preclustering to reduce error. There was a large overlap in reads culled by each method, although AmpliconNoise removed a greater net number of reads. Most OTUs produced by one method had a clearly corresponding partner in the other. Although each method resulted in OTUs consisting entirely of reads that were culled by the other method, there were many more such OTUs formed in the standard pipeline. Total OTU richness was reduced by AmpliconNoise processing, but per-sample OTU richness, diversity and evenness were increased. Increases in per-sample richness and diversity may be a result of AmpliconNoise processing producing a more even OTU rank-abundance distribution. Because communities were randomly subsampled to equalize sample size across communities, and because rare sequence variants are less likely to be selected during subsampling, fewer OTUs were lost from individual communities when subsampling AmpliconNoise-processed data. In contrast to taxon-based diversity estimates, phylogenetic diversity was reduced even on a per-sample basis by de-noising, and samples switched widely in diversity rankings. This work illustrates the significant impacts of processing pipelines on the biological interpretations that can be made from pyrosequencing surveys. This study provides important cautions for analyses of contemporary data, for requisite data archiving (processed vs. non-processed data), and for drawing comparisons among studies performed using distinct data processing pipelines.