A Pan-BCL2 inhibitor renders bone-marrow-resident human leukemia stem cells sensitive to tyrosine kinase inhibition

Leukemia stem cells (LSCs) play a pivotal role in the resistance of chronic myeloid leukemia (CML) to tyrosine kinase inhibitors (TKIs) and its progression to blast crisis (BC), in part, through the alternative splicing of self-renewal and survival genes. To elucidate splice-isoform regulators of human BC LSC maintenance, we performed whole-transcriptome RNA sequencing, splice-isoform-specific quantitative RT-PCR (qRT-PCR), nanoproteomics, stromal coculture, and BC LSC xenotransplantation analyses. Cumulatively, these studies show that the alternative splicing of multiple prosurvival BCL2 family genes promotes malignant transformation of myeloid progenitors into BC LSCS that are quiescent in the marrow niche and that contribute to therapeutic resistance. Notably, sabutoclax, a pan-BCL2 inhibitor, renders marrow-niche-resident BC LSCs sensitive to TKIs at doses that spare normal progenitors. These findings underscore the importance of alternative BCL2 family splice-isoform expression in BC LSC maintenance and suggest that the combinatorial inhibition of prosurvival BCL2 family proteins and BCR-ABL may eliminate dormant LSCs and obviate resistance.

Discovery of cross-reactive probes and polymorphic CpGs in the Illumina Infinium HumanMethylation450 microarray

DNA methylation, an important type of epigenetic modification in humans, participates in crucial cellular processes, such as embryonic development, X-inactivation, genomic imprinting and chromosome stability. Several platforms have been developed to study genome-wide DNA methylation. Many investigators in the field have chosen the Illumina Infinium HumanMethylation microarray for its ability to reliably assess DNA methylation following sodium bisulfite conversion. Here, we analyzed methylation profiles of 489 adult males and 357 adult females generated by the Infinium HumanMethylation450 microarray. Among the autosomal CpG sites that displayed significant methylation differences between the two sexes, we observed a significant enrichment of cross-reactive probes co-hybridizing to the sex chromosomes with more than 94% sequence identity. This could lead investigators to mistakenly infer the existence of significant autosomal sex-associated methylation. Using sequence identity cutoffs derived from the sex methylation analysis, we concluded that 6% of the array probes can potentially generate spurious signals because of co-hybridization to alternate genomic sequences highly homologous to the intended targets. Additionally, we discovered probes targeting polymorphic CpGs that overlapped SNPs. The methylation levels detected by these probes are simply the reflection of underlying genetic polymorphisms but could be misinterpreted as true signals. The existence of probes that are cross-reactive or of target polymorphic CpGs in the Illumina HumanMethylation microarrays can confound data obtained from such microarrays. Therefore, investigators should exercise caution when significant biological associations are found using these array platforms. A list of all cross-reactive probes and polymorphic CpGs identified by us are annotated in this paper.

Genome-wide search for gene-gene interactions in colorectal cancer

Genome-wide association studies (GWAS) have successfully identified a number of single-nucleotide polymorphisms (SNPs) associated with colorectal cancer (CRC) risk. However, these susceptibility loci known today explain only a small fraction of the genetic risk. Gene-gene interaction (GxG) is considered to be one source of the missing heritability. To address this, we performed a genome-wide search for pair-wise GxG associated with CRC risk using 8,380 cases and 10,558 controls in the discovery phase and 2,527 cases and 2,658 controls in the replication phase. We developed a simple, but powerful method for testing interaction, which we term the Average Risk Due to Interaction (ARDI). With this method, we conducted a genome-wide search to identify SNPs showing evidence for GxG with previously identified CRC susceptibility loci from 14 independent regions. We also conducted a genome-wide search for GxG using the marginal association screening and examining interaction among SNPs that pass the screening threshold (p<10⁻⁴). For the known locus rs10795668 (10p14), we found an interacting SNP rs367615 (5q21) with replication p = 0.01 and combined p = 4.19×10⁻⁸. Among the top marginal SNPs after LD pruning (n = 163), we identified an interaction between rs1571218 (20p12.3) and rs10879357 (12q21.1) (nominal combined p = 2.51×10⁻⁶; Bonferroni adjusted p = 0.03). Our study represents the first comprehensive search for GxG in CRC, and our results may provide new insight into the genetic etiology of CRC.

MLH1 region polymorphisms show a significant association with CpG island shore methylation in a large cohort of healthy individuals

Single nucleotide polymorphisms (SNPs) are the most common form of genetic variation. We previously demonstrated that SNPs (rs1800734, rs749072, and rs13098279) in the MLH1 gene region are associated with MLH1 promoter island methylation, loss of MLH1 protein expression, and microsatellite instability (MSI) in colorectal cancer (CRC) patients. Recent studies have identified less CpG-dense "shore" regions flanking many CpG islands. These shores often exhibit distinct methylation profiles between different tissues and matched normal versus tumor cells of patients. To date, most epigenetic studies have focused on somatic methylation events occurring within solid tumors; less is known of the contributions of peripheral blood cell (PBC) methylation to processes such as aging and tumorigenesis. To address whether MLH1 methylation in PBCs is correlated with tumorigenesis we utilized the Illumina 450 K microarrays to measure methylation in PBC DNA of 846 healthy controls and 252 CRC patients from Ontario, Canada. Analysis of a region of chromosome 3p21 spanning the MLH1 locus in healthy controls revealed that a CpG island shore 1 kb upstream of the MLH1 gene exhibits different methylation profiles when stratified by SNP genotypes (rs1800734, rs749072, and rs13098279). Individuals with wild-type genotypes incur significantly higher PBC shore methylation than heterozygous or homozygous variant carriers (p<1.1×10(-6); ANOVA). This trend is also seen in CRC cases (p<0.096; ANOVA). Shore methylation also decreases significantly with increasing age in cases and controls. This is the first study of its kind to integrate PBC methylation at a CpG island shore with SNP genotype status in CRC cases and controls. These results indicate that CpG island shore methylation in PBCs may be influenced by genotype as well as the normal aging process.

Translating genomics to the clinic: implications of cancer heterogeneity

BACKGROUND

Sequencing of cancer genomes has become a pivotal method for uncovering and understanding the deregulated cellular processes driving tumor initiation and progression. Whole-genome sequencing is evolving toward becoming less costly and more feasible on a large scale; consequently, thousands of tumors are being analyzed with these technologies. Interpreting these data in the context of tumor complexity poses a challenge for cancer genomics.

CONTENT

The sequencing of large numbers of tumors has revealed novel insights into oncogenic mechanisms. In particular, we highlight the remarkable insight into the pathogenesis of breast cancers that has been gained through comprehensive and integrated sequencing analysis. The analysis and interpretation of sequencing data, however, must be considered in the context of heterogeneity within and among tumor samples. Only by adequately accounting for the underlying complexity of cancer genomes will the potential of genome sequencing be understood and subsequently translated into improved management of patients.

SUMMARY

The paradigm of personalized medicine holds promise if patient tumors are thoroughly studied as unique and heterogeneous entities and clinical decisions are made accordingly. Associated challenges will be ameliorated by continued collaborative efforts among research centers that coordinate the sharing of mutation, intervention, and outcomes data to assist in the interpretation of genomic data and to support clinical decision-making.

Genome-wide meta-analysis of common variant differences between men and women

The male-to-female sex ratio at birth is constant across world populations with an average of 1.06 (106 male to 100 female live births) for populations of European descent. The sex ratio is considered to be affected by numerous biological and environmental factors and to have a heritable component. The aim of this study was to investigate the presence of common allele modest effects at autosomal and chromosome X variants that could explain the observed sex ratio at birth. We conducted a large-scale genome-wide association scan (GWAS) meta-analysis across 51 studies, comprising overall 114 863 individuals (61 094 women and 53 769 men) of European ancestry and 2 623 828 common (minor allele frequency >0.05) single-nucleotide polymorphisms (SNPs). Allele frequencies were compared between men and women for directly-typed and imputed variants within each study. Forward-time simulations for unlinked, neutral, autosomal, common loci were performed under the demographic model for European populations with a fixed sex ratio and a random mating scheme to assess the probability of detecting significant allele frequency differences. We do not detect any genome-wide significant (P < 5 × 10(-8)) common SNP differences between men and women in this well-powered meta-analysis. The simulated data provided results entirely consistent with these findings. This large-scale investigation across ~115 000 individuals shows no detectable contribution from common genetic variants to the observed skew in the sex ratio. The absence of sex-specific differences is useful in guiding genetic association study design, for example when using mixed controls for sex-biased traits.

Feasibility of real time next generation sequencing of cancer genes linked to drug response: results from a clinical trial

The successes of targeted drugs with companion predictive biomarkers and the technological advances in gene sequencing have generated enthusiasm for evaluating personalized cancer medicine strategies using genomic profiling. We assessed the feasibility of incorporating real-time analysis of somatic mutations within exons of 19 genes into patient management. Blood, tumor biopsy and archived tumor samples were collected from 50 patients recruited from four cancer centers. Samples were analyzed using three technologies: targeted exon sequencing using Pacific Biosciences PacBio RS, multiplex somatic mutation genotyping using Sequenom MassARRAY and Sanger sequencing. An expert panel reviewed results prior to reporting to clinicians. A clinical laboratory verified actionable mutations. Fifty patients were recruited. Nineteen actionable mutations were identified in 16 (32%) patients. Across technologies, results were in agreement in 100% of biopsy specimens and 95% of archival specimens. Profiling results from paired archival/biopsy specimens were concordant in 30/34 (88%) patients. We demonstrated that the use of next generation sequencing for real-time genomic profiling in advanced cancer patients is feasible. Additionally, actionable mutations identified in this study were relatively stable between archival and biopsy samples, implying that cancer mutations that are good predictors of drug response may remain constant across clinical stages.

Abstract 5063: International Cancer Genome Consortium (ICGC)

The International Cancer Genome Consortium (ICGC) was established to bring together researchers from around the globe to comprehensively analyze the genomic, transcriptomic, and epigenomic changes in 50 different tumor types or subtypes that are of clinical and societal importance across the globe. (International network of cancer genome projects (Nature 464, 993-998 (15 April 2010)). As of November 2011, the ICGC has received commitments from funding organizations in Asia, Australia, Europe and North America for 43 project teams in 13 jurisdictions to study over 18,000 tumor genomes. The genomic analyses of tumors conducted by ICGC members in Australia and Canada (pancreatic cancer), Japan (liver cancer), Spain (blood cancer), the UK (breast, lung and skin cancer) and the USA (blood, brain, breast, colon, kidney, lung, ovarian, rectal, stomach and uterine cancer) are now available through the Data Coordination Center housed on the ICGC website at www.icgc.org. The ICGC's informed consent and ethical oversight policies state that cancer patients enrolled in an ICGC-related study should be informed that their participation is voluntary, that their clinical care will not be affected by their participation and that data obtained from analyses using their samples will be made available to the international research community. Ultimately, over 25,000 tumor genomes will be sequenced worldwide. This will provide a comprehensive catalogue of genomic abnormalities associated with cancer, a collection of data that will reveal the repertoire of mutations that cause this wide-ranging disease and help define clinically relevant subtypes of cancer. The data will also provide a rich resource for the world's researchers who are working to develop new treatments to make patient care move forward.

Abstract 3184: Whole genome sequencing of low-input fresh frozen prostate cancer biopsies

Prostate cancer is the most commonly diagnosed malignancy among men in the United States. Due to an aging population, prostate cancer incidence has been increasing, with an estimated 200,000 men being diagnosed in 2010 and more than 32,000 deaths resulting from this disease. Better predictors of patient prognosis and treatment outcome are required to individualize prostate cancer treatment. High-throughput genomic sequence-based approaches offer a unique opportunity to identify biomarkers of disease-progression, thereby enabling more individualized therapy. The Canadian Prostate Cancer Genome Network (CPC-GENE) is an outcomes-based initiative that will sequence 500 specimens from 350 prostate cancer patients over a 5-year time span. Previously, whole genome sequencing efforts from biopsy specimens have been hindered by insufficient quantities of extracted DNA required as input for sequencing library construction. As a proof of concept to demonstrate the ability to sequence low input amounts of DNA from prostate biopsies, whole genome sequencing has been initiated for 50 prostate tumor biopsy samples along with their matched blood-derived reference sample. An on-bead sample preparation protocol was optimized using decreasing quantities of input DNA and used to construct sequencing libraries from as low as 100ng of DNA derived from macrodissected fresh frozen prostate biopsies (&gt;70% cellularity). Sequencing is performed on the Illumina HiSeq 2000 platform to generate coverage depths of 50x for tumor samples and 30x for reference samples. Following alignment using NovoAlign and variant-calling using GATK, we compared our results to genotyping-array results generated using the Affymetrix OncoScan platform. Single-nucleotide variants detected using arrays were validated &gt;99% of the time by sequence data, confirming that the use of a low-input library did not hinder mutation detection. Sequencing does not exhibit significant genome-wide coverage biases, and CNV calls were compared between the genotyping arrays and the next-generation sequencing data. Outcomes from the sequencing and analysis of the initial 50 sample sets will similarly be applied over a 5-year period to characterize an additional 450 prostate specimens. The ability to whole genome sequence specimens where minimal amounts of extracted DNA exist presents new opportunities to sequence many samples previously deemed unusable, while also providing encouraging prospects for whole genome sequencing applications for future studies using biopsy specimens.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3184. doi:1538-7445.AM2012-3184

Abstract LB-230: A prospective clinical trial to evaluate DNA sequencing as a diagnostic tool to guide cancer therapy: results from the initial 50 patients

Background:We are conducting a multicenter clinical trial to evaluate the feasibility of including next-generation sequencing in routine clinical care. Study goals are to determine patient acceptance of research biopsies for genomic sequencing, optimal methods and procedures for sample collection, DNA extraction for successful analysis, review and reporting of mutations back to clinicians and patients with three weeks. Methods: Patients (pts) with metastatic cancer potentially eligible for clinical trials are recruited from 4 cancer centers. A tumor biopsy, blood sample and archived tumor specimens are collected from consenting patients. DNA from samples are analyzed using Pacific Biosciences RS targeted gene sequencing and Sequenom Oncocarta™ V1.0 genotyping. Detected mutations are validated in a CAP/CLIA certified laboratory. An expert panel of clinicians and scientists review results to determine whether results are actionable and reportable to clinicians. Results: As of 01/2012, 50 pts have been recruited. Pt demographics include median age = 57; primary tumor colorectal 9 pts (18%), breast 8 (16%), ovary 8 (16%), lung 5 (10%), others 20 (40%); median number prior treatments = 3; median time with metastatic disease = 17 months. Over 90% of approached pts consented to the study. Molecular profiling by Pacific Biosciences RS and Sequenom was successful in 43 pts (86%) with 100% concordance between genomic platforms. Somatic mutations were identified in over 30% of pts; 75% of these (including mutations in KRAS, PIK3CA, EGFR, RET, KIT) were deemed actionable. Seven pts (14%) had treatment impacted by matching a targeted therapy to the genetic profile; 4 patients had benefit (1 PR in ovarian cancer, 1 SD in breast cancer, 2 clinical benefits in thyroid and unknown primary squamous cell cancers). Four pts had novel mutations in AKT1, PDGFRA, EGFR and KRAS not present on the Oncocarta panel demonstrating the added benefit of sequencing the entire exon. Genomic results from of archived tumor specimens and fresh tumor biopsies matched in 26 of 30 patients (90%) with paired samples. 62% of pts had delivery of a clinical report within &lt;/= 21 days. Bioinformatics tools developed to assist with sample handling, analyses and reporting mechanisms are being optimized for routine inclusion into the clinical environment. Mutation specific reporting templates have been developed to provide results and curetted information from publically available sources. Conclusion: The study is on track to meet the pre-defined study benchmarks for patient recruitment, sample quality, and turnaround time. Our results indicate that high throughput sequencing with clinical laboratory verification of results is feasible and may be used as a clinical tool to guide cancer therapy and add value to the information generated by traditional genotyping methods.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-230. doi:1538-7445.AM2012-LB-230

Characterization of gene-environment interactions for colorectal cancer susceptibility loci

Genome-wide association studies (GWAS) have identified more than a dozen loci associated with colorectal cancer (CRC) risk. Here, we examined potential effect-modification between single-nucleotide polymorphisms (SNP) at 10 of these loci and probable or established environmental risk factors for CRC in 7,016 CRC cases and 9,723 controls from nine cohort and case-control studies. We used meta-analysis of an efficient empirical-Bayes estimator to detect potential multiplicative interactions between each of the SNPs [rs16892766 at 8q23.3 (EIF3H/UTP23), rs6983267 at 8q24 (MYC), rs10795668 at 10p14 (FLJ3802842), rs3802842 at 11q23 (LOC120376), rs4444235 at 14q22.2 (BMP4), rs4779584 at 15q13 (GREM1), rs9929218 at 16q22.1 (CDH1), rs4939827 at 18q21 (SMAD7), rs10411210 at 19q13.1 (RHPN2), and rs961253 at 20p12.3 (BMP2)] and select major CRC risk factors (sex, body mass index, height, smoking status, aspirin/nonsteroidal anti-inflammatory drug use, alcohol use, and dietary intake of calcium, folate, red meat, processed meat, vegetables, fruit, and fiber). The strongest statistical evidence for a gene-environment interaction across studies was for vegetable consumption and rs16892766, located on chromosome 8q23.3, near the EIF3H and UTP23 genes (nominal P(interaction) = 1.3 × 10(-4); adjusted P = 0.02). The magnitude of the main effect of the SNP increased with increasing levels of vegetable consumption. No other interactions were statistically significant after adjusting for multiple comparisons. Overall, the association of most CRC susceptibility loci identified in initial GWAS seems to be invariant to the other risk factors considered; however, our results suggest potential modification of the rs16892766 effect by vegetable consumption.

Abstract 1853: Identification and characterization of genes in regions of recurrent genomic gain as putative therapeutic targets in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related mortality in the United States. PDAC presents with the worst prognosis of all solid tumors and the 5-year survival rate for patients with advanced PDAC is only 2%. Current chemotherapies fail to attenuate the aggressiveness of this disease and as such, novel therapeutic strategies are needed. The purpose of our study is to identify putative therapeutic targets in PDAC and characterize the role of a target gene in tumor progression. Towards this aim, we sought to identify genes which are recurrently gained or amplified in pancreatic tumors. If increased copy of specific genes confers neoplastic properties, selective targeting of such genes may have therapeutic implications. We obtained publically available copy number alteration data on 60 PDAC genomes characterized in four independent PDAC studies. Using bioinformatics and computational approaches, we identified 20 genomic loci that are gained in at least one sample in three of the four PDAC datasets. Our integrated analysis of the genes mapping to these 20 loci results in a catalogue of 710 protein-coding genes and 46 miRNA genes, which are candidate targets for further analysis. In order to delineate appropriate biological models for functional validation of these genes in PDAC, we obtained SNP array-based copy number data using the Illumina OmniExpress platform and gene expression analysis from Illumina HT-12 BeadChip arrays from 30 human PDAC cell lines. We identified genes from our candidate gene list in which copy number alteration and gene expression are correlated as computed by a Spearman rank correlation coefficient, α. This gene set was enriched for genes with high correlation between copy number and expression in comparison to simulated gene sets (p = 0.007). Our data suggest that Epithelial cell-transforming sequence 2 oncogene (ECT2) on 3q26.3 is a strong candidate for functional validation. This gene encodes a Rho-specific guanine exchange factor involved in various cellular processes including regulation of G1-to-S phase transition in cell-cycle progression. To validate our in silico findings, we have designed experiments to investigate the role of ECT2 amplification in PDAC, using the 30 human PDAC cell lines we have genetically analyzed. This will be accomplished through differential inhibition of the ECT2 protein, using RNAi and small molcules, in cell lines in which ECT2 is amplified, compared to appropriate control lines. In conclusion, we have identified a set of candidate target genes in PDAC and are currently validating the role of one of these targets, ECT2, in PDAC tumor progression.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1853. doi:1538-7445.AM2012-1853

The genetic basis for cancer treatment decisions

Personalized cancer medicine is based on increased knowledge of the cancer mutation repertoire and availability of agents that target altered genes or pathways. Given advances in cancer genetics, technology, and therapeutics development, the timing is right to develop a clinical trial and research framework to move future clinical decisions from heuristic to evidence-based decisions. Although the challenges of integrating genomic testing into cancer treatment decision making are wide-ranging and complex, there is a scientific and ethical imperative to realize the benefits of personalized cancer medicine, given the overwhelming burden of cancer and the unprecedented opportunities for advancements in outcomes for patients.

Cancer Genomics: Technology, Discovery, and Translation

In recent years, the increasing awareness that somatic mutations and other genetic aberrations drive human malignancies has led us within reach of personalized cancer medicine (PCM). The implementation of PCM is based on the following premises: genetic aberrations exist in human malignancies; a subset of these aberrations drive oncogenesis and tumor biology; these aberrations are actionable (defined as having the potential to affect management recommendations based on diagnostic, prognostic, and/or predictive implications); and there are highly specific anticancer agents available that effectively modulate these targets. This article highlights the technology underlying cancer genomics and examines the early results of genome sequencing and the challenges met in the discovery of new genetic aberrations. Finally, drawing from experiences gained in a feasibility study of somatic mutation genotyping and targeted exome sequencing led by Princess Margaret Hospital–University Health Network and the Ontario Institute for Cancer Research, the processes, challenges, and issues involved in the translation of cancer genomics to the clinic are discussed.

Meta-analysis of new genome-wide association studies of colorectal cancer risk

Colorectal cancer is the second leading cause of cancer death in developed countries. Genome-wide association studies (GWAS) have successfully identified novel susceptibility loci for colorectal cancer. To follow up on these findings, and try to identify novel colorectal cancer susceptibility loci, we present results for GWAS of colorectal cancer (2,906 cases, 3,416 controls) that have not previously published main associations. Specifically, we calculated odds ratios and 95% confidence intervals using log-additive models for each study. In order to improve our power to detect novel colorectal cancer susceptibility loci, we performed a meta-analysis combining the results across studies. We selected the most statistically significant single nucleotide polymorphisms (SNPs) for replication using ten independent studies (8,161 cases and 9,101 controls). We again used a meta-analysis to summarize results for the replication studies alone, and for a combined analysis of GWAS and replication studies. We measured ten SNPs previously identified in colorectal cancer susceptibility loci and found eight to be associated with colorectal cancer (p value range 0.02 to 1.8 × 10(-8)). When we excluded studies that have previously published on these SNPs, five SNPs remained significant at p < 0.05 in the combined analysis. No novel susceptibility loci were significant in the replication study after adjustment for multiple testing, and none reached genome-wide significance from a combined analysis of GWAS and replication. We observed marginally significant evidence for a second independent SNP in the BMP2 region at chromosomal location 20p12 (rs4813802; replication p value 0.03; combined p value 7.3 × 10(-5)). In a region on 5p33.15, which includes the coding regions of the TERT-CLPTM1L genes and has been identified in GWAS to be associated with susceptibility to at least seven other cancers, we observed a marginally significant association with rs2853668 (replication p value 0.03; combined p value 1.9 × 10(-4)). Our study suggests a complex nature of the contribution of common genetic variants to risk for colorectal cancer.

Analysis of early C2C12 myogenesis identifies stably and differentially expressed transcriptional regulators whose knock-down inhibits myoblast differentiation

Myogenesis is a tightly controlled process involving the transcriptional activation and repression of thousands of genes. Although many components of the transcriptional network regulating the later phases of myogenesis have been identified, relatively few studies have described the transcriptional landscape during the first 24 h, when myoblasts commit to differentiate. Through dense temporal profiling of differentiating C2C12 myoblasts, we identify 193 transcriptional regulators (TRs) whose expression is significantly altered within the first 24 h of myogenesis. A high-content shRNA screen of 77 TRs involving 427 stable lines identified 42 genes whose knockdown significantly inhibits differentiation of C2C12 myoblasts. Of the TRs that were differentially expressed within the first 24 h, over half inhibited differentiation when knocked down, including known regulators of myogenesis (Myod1, Myog, and Myf5), as well as 19 TRs not previously associated with this process. Surprisingly, a similar proportion (55%) of shRNAs targeting TRs whose expression did not change also inhibited C2C12 myogenesis. We further show that a subset of these TRs inhibits myogenesis by downregulating expression of known regulatory and structural proteins. Our findings clearly illustrate that several TRs critical for C2C12 myogenesis are not differentially regulated, suggesting that approaches that focus functional studies on differentially-expressed transcripts will fail to provide a comprehensive view of this complex process.

Genetic variants and susceptibility to neurological complications following West Nile virus infection

To determine genetic factors predisposing to neurological complications following West Nile virus infection, we analyzed a cohort of 560 neuroinvasive case patients and 950 control patients for 13 371 mostly nonsynonymous single-nucleotide polymorphisms (SNPs). The top 3 SNPs on the basis of statistical significance were also in genes of biological plausibility: rs2066786 in RFC1 (replication factor C1) (P = 1.88 × 10⁻⁵; odds ratio [OR], 0.68 [95% confidence interval {CI}, .56–.81]); rs2298771 in SCN1A (sodium channel, neuronal type I α subunit) (P = 5.87 × 10⁻⁵; OR, 1.47 [95% CI, 1.21–1.77]); and rs25651 in ANPEP (ananyl aminopeptidase) (P = 1.44 × 10⁻⁴; OR, 0.69 [95% CI, .56–.83]). Additional genotyping of these SNPs in a separate sample of 264 case patients and 296 control patients resulted in a lack of significance in the replication cohort; joint significance was as follows: rs2066786, P = .0022; rs2298771, P = .005; rs25651, P = .042. Using mostly nonsynonymous variants, we therefore did not identify genetic variants associated with neuroinvasive disease.

Abstract B48: Feasibility study of molecular profiling (MP) in patients (Pts) with advanced solid cancers using targeted mutation analysis and targeted exome sequencing

Background: As the development of molecularly targeted agents is increasingly linked to predictive biomarkers, there is a need for novel strategies of cancer genome characterization at the point of care. This study assesses the feasibility of biopsying pts with advanced solid cancers for MP using both targeted exome sequencing and targeted mutation analysis. Metrics of feasibility include delivering results within 21 days and identifying “actionable” mutations in at least 30% of pts.

Method: Total accrual of 50–100 pts from 5 centers is planned. Enrolled pts undergo a tumor biopsy, blood sample and retrieval of archived tumor specimens. Each biopsy sample is divided for fixation by snap freezing and formalin. Following DNA extraction, germline and somatic mutations are evaluated using two platforms: 1) Targeted mutation analysis by Sequenom™ MassARRAY using Oncocarta 1.0 (238 mutations from 19 genes) in a CLIA certified laboratory and 2) Targeted exome sequencing by Pacific Biosciences™ PacBio RS initially sequencing exomes from the Oncocarta genes with planned expansion to over 1,000 genes. Identified mutations are confirmed by Sanger sequencing in a CLIA certified laboratory. An expert panel reviews MP results prior to generating reports. Customized MP reports detail mutations identified, platforms used, genes examined, failed mutation analyses and clinical significance of mutations detected according to literature review. Impact of MP on treatment decisions is recorded at regular intervals for up to 2 years.

Results: We report results from the first 15 pts enrolled. Median age was 52 years (range 44–71). Most common primary tumor types were breast (5) and colorectal (3). Fourteen pts underwent successful tumor biopsies: 8 required radiological guidance, 4 were performed by clinicians at bedside and 2 had samples obtained during palliative surgery. One pt had tumor deemed inaccessible at time of biopsy. One adverse event of a minor skin infection at biopsy site was observed. Median number of cores per radiological biopsy was 4 (range 3–5). Median tumor cellularity in biopsy samples was 60% (range 0–90). MP was possible in 12 (86%) of the 14 biopsied pts: 2 pts had insufficient DNA from biopsy. In pts completing MP, median time for MP analysis was 14 days (range 8–28) and median time from consent to result was 22 days (range 15–35). Actionable mutations were identified in biopsy samples of 7 (57%) pts; mutated genes include PIK3CA (3), KRAS (3) and EGFR (1). An additional novel non Oncocarta somatic mutation was identified by PacBio RS and validated by Sanger: a PDGFRA mutation of unknown significance in a KRAS mutant colon cancer pt. Agreement between platforms was 100% for Oncocarta mutations. Snap freezing was abandoned in favor of formalin fixation alone as their comparisons revealed concordant results and greater DNA quantity was recovered from the latter. At the first follow up time-point, 3 (20%) pts had treatment decisions impacted by M P.

Conclusion: Early results from this study demonstrate that biopsying pts with advanced tumors for MP using targeted exome sequencing and targeted mutation analysis is feasible. MP reports can be generated in a timely manner and “actionable” mutations are identified in 57% of pts. These early results demonstrate that identifying mutations by MP may impact treatment recommendations.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B48.

Unraveling the genetics of cancer: genome sequencing and beyond

Advances in next-generation sequencing technology are enabling the systematic analyses of whole cancer genomes, providing insights into the landscape of somatic mutations and the great genetic heterogeneity that defines the unique signature of an individual tumor. Moreover, integrated studies of the genome, epigenome, and transcriptome reveal mechanisms of tumorigenesis at multiple levels. Progress in sequencing technologies and bioinformatics will improve the costs, sensitivity, and accuracy of detecting somatic mutations, while large-scale projects are underway to coordinate cancer genome sequencing at the global level to facilitate the generation and dissemination of high-quality uniform genetic data. These developments will create opportunities for deeper studies of cancer genetics and the clinical application of genome sequencing, and will motivate further research in cancer pathogenesis.

From genomic databases to translation: a call to action

The rapid rise of international collaborative science has enabled access to genomic data. In this article, it is argued that to move beyond mapping genomic variation to understanding its role in complex disease aetiology and treatment will require extending data sharing for the purposes of clinical research translation and implementation.

Is rigorous retrospective harmonization possible? Application of the DataSHaPER approach across 53 large studies

BACKGROUND

Proper understanding of the roles of, and interactions between genetic, lifestyle, environmental and psycho-social factors in determining the risk of development and/or progression of chronic diseases requires access to very large high-quality databases. Because of the financial, technical and time burdens related to developing and maintaining very large studies, the scientific community is increasingly synthesizing data from multiple studies to construct large databases. However, the data items collected by individual studies must be inferentially equivalent to be meaningfully synthesized. The DataSchema and Harmonization Platform for Epidemiological Research (DataSHaPER; http://www.datashaper.org) was developed to enable the rigorous assessment of the inferential equivalence, i.e. the potential for harmonization, of selected information from individual studies.

METHODS

This article examines the value of using the DataSHaPER for retrospective harmonization of established studies. Using the DataSHaPER approach, the potential to generate 148 harmonized variables from the questionnaires and physical measures collected in 53 large population-based studies (6.9 million participants) was assessed. Variable and study characteristics that might influence the potential for data synthesis were also explored.

RESULTS

Out of all assessment items evaluated (148 variables for each of the 53 studies), 38% could be harmonized. Certain characteristics of variables (i.e. relative importance, individual targeted, reference period) and of studies (i.e. observational units, data collection start date and mode of questionnaire administration) were associated with the potential for harmonization. For example, for variables deemed to be essential, 62% of assessment items paired could be harmonized.

CONCLUSION

The current article shows that the DataSHaPER provides an effective and flexible approach for the retrospective harmonization of information across studies. To implement data synthesis, some additional scientific, ethico-legal and technical considerations must be addressed. The success of the DataSHaPER as a harmonization approach will depend on its continuing development and on the rigour and extent of its use. The DataSHaPER has the potential to take us closer to a truly collaborative epidemiology and offers the promise of enhanced research potential generated through synthesized databases.

Cancer genome variation in children, adolescents, and young adults

This mini-review describes the rapid changes in genome technologies that are leading to comprehensive views of genetic alterations in cancer, and presents high-level thoughts on ways to accelerate translation into clinical medicine. Issues that are more relevant to children, adolescents, and young adult patients with cancer are highlighted.