Tyler Izatt

Germline Mutations in HOXB13 and Prostate-Cancer Risk

BACKGROUND Family history is a significant risk factor for prostate cancer, although the molecular basis for this association is poorly understood. Linkage studies have implicated chromosome 17q21-22 as a possible location of a prostate-cancer susceptibility gene. METHODS We screened more than 200 genes in the 17q21-22 region by sequencing germline DNA from 94 unrelated patients with prostate cancer from families selected for linkage to the candidate region. We tested family members, additional case subjects, and control subjects to characterize the frequency of the identified mutations. RESULTS Probands from four families were discovered to have a rare but recurrent mutation (G84E) in HOXB13 (rs138213197), a homeobox transcription factor gene that is important in prostate development. All 18 men with prostate cancer and available DNA in these four families carried the mutation. The carrier rate of the G84E mutation was increased by a factor of approximately 20 in 5083 unrelated subjects of European descent who had prostate cancer, with the mutation found in 72 subjects (1.4%), as compared with 1 in 1401 control subjects (0.1%) (P=8.5x10(-7)). The mutation was significantly more common in men with early-onset, familial prostate cancer (3.1%) than in those with late-onset, nonfamilial prostate cancer (0.6%) (P=2.0x10(-6)). CONCLUSIONS The novel HOXB13 G84E variant is associated with a significantly increased risk of hereditary prostate cancer. Although the variant accounts for a small fraction of all prostate cancers, this finding has implications for prostate-cancer risk assessment and may provide new mechanistic insights into this common cancer. (Funded by the National Institutes of Health and others.).

Integrated genomic characterization reveals novel, therapeutically relevant drug targets in FGFR and EGFR pathways in sporadic intrahepatic cholangiocarcinoma.

Advanced cholangiocarcinoma continues to harbor a difficult prognosis and therapeutic options have been limited. During the course of a clinical trial of whole genomic sequencing seeking druggable targets, we examined six patients with advanced cholangiocarcinoma. Integrated genome-wide and whole transcriptome sequence analyses were performed on tumors from six patients with advanced, sporadic intrahepatic cholangiocarcinoma (SIC) to identify potential therapeutically actionable events. Among the somatic events captured in our analysis, we uncovered two novel therapeutically relevant genomic contexts that when acted upon, resulted in preliminary evidence of anti-tumor activity. Genome-wide structural analysis of sequence data revealed recurrent translocation events involving the FGFR2 locus in three of six assessed patients. These observations and supporting evidence triggered the use of FGFR inhibitors in these patients. In one example, preliminary anti-tumor activity of pazopanib (in vitro FGFR2 IC50≈350 nM) was noted in a patient with an FGFR2-TACC3 fusion. After progression on pazopanib, the same patient also had stable disease on ponatinib, a pan-FGFR inhibitor (in vitro, FGFR2 IC50≈8 nM). In an independent non-FGFR2 translocation patient, exome and transcriptome analysis revealed an allele specific somatic nonsense mutation (E384X) in ERRFI1, a direct negative regulator of EGFR activation. Rapid and robust disease regression was noted in this ERRFI1 inactivated tumor when treated with erlotinib, an EGFR kinase inhibitor. FGFR2 fusions and ERRFI mutations may represent novel targets in sporadic intrahepatic cholangiocarcinoma and trials should be characterized in larger cohorts of patients with these aberrations.

Genome and Transcriptome Sequencing in Prospective Metastatic Triple-Negative Breast Cancer Uncovers Therapeutic Vulnerabilities

Triple-negative breast cancer (TNBC) is characterized by the absence of expression of estrogen receptor, progesterone receptor, and HER-2. Thirty percent of patients recur after first-line treatment, and metastatic TNBC (mTNBC) has a poor prognosis with median survival of one year. Here, we present initial analyses of whole genome and transcriptome sequencing data from 14 prospective mTNBC. We have cataloged the collection of somatic genomic alterations in these advanced tumors, particularly those that may inform targeted therapies. Genes mutated in multiple tumors included TP53, LRP1B, HERC1, CDH5, RB1, and NF1. Notable genes involved in focal structural events were CTNNA1, PTEN, FBXW7, BRCA2, WT1, FGFR1, KRAS, HRAS, ARAF, BRAF, and PGCP. Homozygous deletion of CTNNA1 was detected in 2 of 6 African Americans. RNA sequencing revealed consistent overexpression of the FOXM1 gene when tumor gene expression was compared with nonmalignant breast samples. Using an outlier analysis of gene expression comparing one cancer with all the others, we detected expression patterns unique to each patients tumor. Integrative DNA/RNA analysis provided evidence for deregulation of mutated genes, including the monoallelic expression of TP53 mutations. Finally, molecular alterations in several cancers supported targeted therapeutic intervention on clinical trials with known inhibitors, particularly for alterations in the RAS/RAF/MEK/ERK and PI3K/AKT/mTOR pathways. In conclusion, whole genome and transcriptome profiling of mTNBC have provided insights into somatic events occurring in this difficult to treat cancer. These genomic data have guided patients to investigational treatment trials and provide hypotheses for future trials in this irremediable cancer. Mol Cancer Ther; 12(1); 104–16. ©2012 AACR.

Personalized treatment of Sézary syndrome by targeting a novel CTLA4:CD28 fusion

Matching molecularly targeted therapies with cancer subtype‐specific gene mutations is revolutionizing oncology care. However, for rare cancers this approach is problematic due to the often poor understanding of the diseases natural history and phenotypic heterogeneity, making treatment of these cancers a particularly unmet medical need in clinical oncology. Advanced Sézary syndrome (SS), an aggressive, exceedingly rare variant of cutaneous T‐cell lymphoma (CTCL) is a prototypical example of a rare cancer. Through whole genome and RNA sequencing (RNA‐seq) of a SS patients tumor we discovered a highly expressed gene fusion between CTLA4 (cytotoxic T lymphocyte antigen 4) and CD28 (cluster of differentiation 28), predicting a novel stimulatory molecule on the surface of tumor T cells. Treatment with the CTLA4 inhibitor ipilimumab resulted in a rapid clinical response. Our findings suggest a novel driver mechanism for SS, and cancer in general, and exemplify an emerging model of cancer treatment using exploratory genomic analysis to identify a personally targeted treatment option when conventional therapies are exhausted.

Extramedullary myeloma whole genome sequencing reveals novel mutations in Cereblon, proteasome subunit G2 and the glucocorticoid receptor in multi drug resistant disease.

Extramedullary disease (EMD) in Multiple Myeloma (MM) is characterized by the detection of monoclonal plasma cells outside the bone marrow niche, and is frequently associated with poor prognosis. Here we describe novel genomic events leading to drug refractory disease in a heavily pretreated 37-year-old IgG-kappa MM patient presenting with progressive, multi-drug refractory EMD. For the first time we report an acquired truncating mutation of Cereblon (CRBN) as well as point mutations in proteasome subunit G2 and the glucocorticoid receptor as an explanation for drug resistance. Initial myeloma treatment for the patient occurred over multiple years and included the immunomodulatory drugs (IMiDs) thalidomide and lenalidomide, the proteasome inhibitor bortezomib, cortiosteroids, radiation, one autologous and two allogeneic transplantations. She experienced extramedullary relapse, presenting as an extensive neck mass and smaller soft tissue nodules in the upper left triceps. The most recent therapy immediately prior to genomic sequencing was hyper-CVAD (hyperfractionated cyclophosphamide, vincristine, doxorubicin and dexamethasone) incorporating alkylating agent cyclophosphamide with transient minor response. The patient was then enrolled in a pilot study utilizing next generation sequencing (NGS) to identify novel markers and potential therapeutic targets. Samples were acquired with patient consent in compliance with Mayo Clinic Institutional Review Board. For this study we completed array comparative genomic hybridization, whole exome, whole genome (insert = 1 kb) and RNA sequencing (RNASeq) of a biopsy taken from the neck mass to thoroughly interrogate the tumour genome of this patient. The presence of mutations of interest was evaluated by capillary sequencing in an expanded cohort of 25 CD138+ MM samples with low CRBN expression. The neck mass pathology confirmed sheets of atypical plasma cells, kappa light chain restriction, CD138+, CD20− and CD45−. Array comparative genomic hybridization revealed multiple copy number abnormalities, most notably del1(p13.2–34.2), monosomy 13 and monosomy X. Therapy subsequent to biopsy for genome sequencing was with pomalidomide and dexamethasone without response. Unfortunately, the patient succumbed to her disease in less than the 12 weeks required at the time for sequencing and data analysis. Sequencing revealed a highly disturbed genome (Figure 1) consisting of 4 somatic insertions/deletions, 38 intra-chromosomal rearrangements, and 35 translocations, including the high risk marker and initiating tumour event t(14;16). Furthermore, 271 nonsynonymous, somatic point mutations were detected in genes including KRAS, PIK3CA, ATM, and NFKB2 (Table I). Importantly, a Q99* truncating mutation as well as a R283K point mutation were observed in CRBN, that we recently demonstrated as essential for the anti-MM action of IMiDs (Zhu, et al 2011). To our knowledge this is the first documented mutation of Cereblon in a primary myeloma sample. Additional sequencing of CRBN in the expanded cohort of 25 patients revealed a synonymous mutation in only one sample. Figure 1 Circos plot depicting genome wide somatic variants, rearrangements and copy number changes derived from next generation sequencing. Numbers with circles around them indicate the following: 1) somatic single nucleotide variation (SNV), 2) location of SNV ... Table I Summary of clinically relevant single nucleotide variations We also observed in the patient biopsy a potentially clinically relevant nonsynonymous point mutation in proteasome assembly chaperone 2, PSMG2 (E171K). PSMG2 is a proteasome assembly protein involved in mammalian 20S proteasome maturation (Hirano, et al 2005). Mutations in proteasome assembly components contribute to proteasome inhibitor resistance (Keats, et al 2007), possibly explaining this patient’s bortezomib-refractory disease. Capillary sequencing of PSMG2 in our expanded cohort revealed no mutations, although exonic deletion of PSMG2 has also been reported in myeloma (Walker, et al 2012). The last nonsynonymous point mutation associated with drug resistance was identified in NR3C1 (G369A), a glucocorticoid receptor. Mutation of NR3C1 has been associated with resistance to steroid therapy (Bray and Cotton 2003), which this patient received and proved refractory. No NR3C1 mutations were identified in our expanded cohort and none have been previously reported in other myeloma genomes (Chapman, et al 2011, Walker, et al 2012). Mutations in NR3C1 have however been described in the glucocorticoid resistant MM.1R cell line (Moalli, et al 1992). Patients with low NR3C1 expression levels who received thalidomide demonstrated better progression-free survival and overall survival than those with low NR3C1 who did not receive thalidomide (Heuck, et al 2012). While these mutations suggest causality of drug-refractory disease, they do not identify pathways that can be exploited with targeted therapies. Additional mutations were observed in pathways for which targeted therapies are available. This patient had mutations in KRAS (G12C) and in ATM (T1985I), both of which affect the signalling of MEK downstream, thus making MEK a therapeutic target of interest in this patient. While there are no approved MEK inhibitors available for MM treatment, more than 100 trials are currently investigating MEK inhibitors, of which three of these trials are being conducted in MM patients (www.clinicaltrials.gov). The patient tumour also contained canonical, activating mutations in PIK3CA (E542K). Interestingly, one study demonstrated that 64% of PIK3CA mutations occur in exon 9, where codon 542 is located. Moreover, 19% of patients with PIK3CA mutations also presented with KRAS mutations, of which 9% are G12C (Janku, et al 2012), found in our patient. The PI3K pathway is vitally important as it regulates downstream targets, such as AKT and MTOR, which are responsible for cell proliferation, growth, survival and metastasis (Bartholomeusz and Gonzalez-Angulo 2012). In addition, a number of clinical trials are currently investigating PIK3 inhibitors (www.clinicaltrials.gov). In summary, this is the first description of CRBN mutations in a primary myeloma sample and furthermore of a “triple negative” MM patient possessing mutations probably contributing to resistance to all three major drug classes utilized in MM therapy. These mutations were not replicated in our validation cohort of 25 patients with low level CRBN expression and functional data have not yet been obtained, thus further investigation is necessary to better understand the mutation frequency and the functional significance of mutation in these genes. In summary, our approach utilizing comprehensive next generation sequencing not only identified mutations suggestive of the patient’s refractory disease, but also revealed unforeseen therapeutic options highlighting the importance of this technology in advancing individualized medicine.

Paired Tumor and Normal Whole Genome Sequencing of Metastatic Olfactory Neuroblastoma

Background Olfactory neuroblastoma (ONB) is a rare cancer of the sinonasal tract with little molecular characterization. We performed whole genome sequencing (WGS) on paired normal and tumor DNA from a patient with metastatic-ONB to identify the somatic alterations that might be drivers of tumorigenesis and/or metastatic progression. Methodology/Principal Findings Genomic DNA was isolated from fresh frozen tissue from a metastatic lesion and whole blood, followed by WGS at >30X depth, alignment and mapping, and mutation analyses. Sanger sequencing was used to confirm selected mutations. Sixty-two somatic short nucleotide variants (SNVs) and five deletions were identified inside coding regions, each causing a non-synonymous DNA sequence change. We selected seven SNVs and validated them by Sanger sequencing. In the metastatic ONB samples collected several months prior to WGS, all seven mutations were present. However, in the original surgical resection specimen (prior to evidence of metastatic disease), mutations in KDR, MYC, SIN3B, and NLRC4 genes were not present, suggesting that these were acquired with disease progression and/or as a result of post-treatment effects. Conclusions/Significance This work provides insight into the evolution of ONB cancer cells and provides a window into the more complex factors, including tumor clonality and multiple driver mutations.

Whole genome sequencing reveals potential targets for therapy in patients with refractory KRAS mutated metastatic colorectal cancer

BackgroundThe outcome of patients with metastatic colorectal carcinoma (mCRC) following first line therapy is poor, with median survival of less than one year. The purpose of this study was to identify candidate therapeutically targetable somatic events in mCRC patient samples by whole genome sequencing (WGS), so as to obtain targeted treatment strategies for individual patients.MethodsFour patients were recruited, all of whom had received > 2 prior therapy regimens. Percutaneous needle biopsies of metastases were performed with whole blood collection for the extraction of constitutional DNA. One tumor was not included in this study as the quality of tumor tissue was not sufficient for further analysis. WGS was performed using Illumina paired end chemistry on HiSeq2000 sequencing systems, which yielded coverage of greater than 30X for all samples. NGS data were processed and analyzed to detect somatic genomic alterations including point mutations, indels, copy number alterations, translocations and rearrangements.ResultsAll 3 tumor samples had KRAS mutations, while 2 tumors contained mutations in the APC gene and the PIK3CA gene. Although we did not identify a TCF7L2-VTI1A translocation, we did detect a TCF7L2 mutation in one tumor. Among the other interesting mutated genes was INPPL1, an important gene involved in PI3 kinase signaling. Functional studies demonstrated that inhibition of INPPL1 reduced growth of CRC cells, suggesting that INPPL1 may promote growth in CRC.ConclusionsOur study further supports potential molecularly defined therapeutic contexts that might provide insights into treatment strategies for refractory mCRC. New insights into the role of INPPL1 in colon tumor cell growth have also been identified. Continued development of appropriate targeted agents towards specific events may be warranted to help improve outcomes in CRC.

Clinical Implementation of Integrated Genomic Profiling in Patients with Advanced Cancers

DNA focused panel sequencing has been rapidly adopted to assess therapeutic targets in advanced/refractory cancer. Integrated Genomic Profiling (IGP) utilising DNA/RNA with tumour/normal comparisons in a Clinical Laboratory Improvement Amendments (CLIA) compliant setting enables a single assay to provide: therapeutic target prioritisation, novel target discovery/application and comprehensive germline assessment. A prospective study in 35 advanced/refractory cancer patients was conducted using CLIA-compliant IGP. Feasibility was assessed by estimating time to results (TTR), prioritising/assigning putative therapeutic targets, assessing drug access, ascertaining germline alterations, and assessing patient preferences/perspectives on data use/reporting. Therapeutic targets were identified using biointelligence/pathway analyses and interpreted by a Genomic Tumour Board. Seventy-five percent of cases harboured 1–3 therapeutically targetable mutations/case (median 79 mutations of potential functional significance/case). Median time to CLIA-validated results was 116 days with CLIA-validation of targets achieved in 21/22 patients. IGP directed treatment was instituted in 13 patients utilising on/off label FDA approved drugs (n = 9), clinical trials (n = 3) and single patient IND (n = 1). Preliminary clinical efficacy was noted in five patients (two partial response, three stable disease). Although barriers to broader application exist, including the need for wider availability of therapies, IGP in a CLIA-framework is feasible and valuable in selection/prioritisation of anti-cancer therapeutic targets.

Simultaneous characterization of somatic events and HPV-18 integration in a metastatic cervical carcinoma patient using DNA and RNA sequencing.

Objective Integration of carcinogenic human papillomaviruses (HPVs) into the host genome is a significant tumorigenic factor in specific cancers including cervical carcinoma. Although major strides have been made with respect to HPV diagnosis and prevention, identification and development of efficacious treatments for cervical cancer patients remains a goal and thus requires additional detailed characterization of both somatic events and HPV integration. Given this need, the goal of this study was to use the next generation sequencing to simultaneously evaluate somatic alterations and expression changes in a patient’s cervical squamous carcinoma lesion metastatic to the lung and to detect and analyze HPV infection in the same sample. Materials and Methods We performed tumor and normal exome, tumor and normal shallow whole-genome sequencing, and RNA sequencing of the patient’s lung metastasis. Results We generated over 1.2 billion mapped reads and identified 130 somatic point mutations and indels, 21 genic translocations, 16 coding regions demonstrating copy number changes, and over 36 genes demonstrating altered expression in the tumor (corrected P < 0.05). Sequencing also revealed the HPV type 18 (HPV-18) integration in the metastasis. Using both DNA and RNA reads, we pinpointed 3 major events indicating HPV-18 integration into an intronic region of chromosome 6p25.1 in the patient’s tumor and validated these events with Sanger sequencing. This integration site has not been reported for HPV-18. Conclusions We demonstrate that DNA and RNA sequencing can be used to concurrently characterize somatic alterations and expression changes in a biopsy and delineate HPV integration at base resolution in cervical cancer. Further sequencing will allow us to better understand the molecular basis of cervical cancer pathogenesis.

An integrated framework for reporting clinically relevant biomarkers from paired tumor/normal genomic and transcriptomic sequencing data in support of clinical trials in personalized medicine

The ability to rapidly sequence the tumor and germline DNA of an individual holds the eventual promise of revolutionizing our ability to match targeted therapies to tumors harboring the associated genetic biomarkers. Analyzing high throughput genomic data consisting of millions of base pairs and discovering alterations in clinically actionable genes in a structured and real time manner is at the crux of personalized testing. This requires a computational architecture that can monitor and track a system within a regulated environment as terabytes of data are reduced to a small number of therapeutically relevant variants, delivered as a diagnostic laboratory developed test. These high complexity assays require data structures that enable real-time and retrospective ad-hoc analysis, with a capability of updating to keep up with the rapidly changing genomic and therapeutic options, all under a regulated environment that is relevant under both CMS and FDA depending on application. We describe a flexible computational framework that uses a paired tumor/normal sample allowing for complete analysis and reporting in approximately 24 hours, providing identification of single nucleotide changes, small insertions and deletions, chromosomal rearrangements, gene fusions and gene expression with positive predictive values over 90%. In this paper we present the challenges in integrating clinical, genomic and annotation databases to provide interpreted draft reports which we utilize within ongoing clinical research protocols. We demonstrate the need to retire from existing performance measurements of accuracy and specificity and measure metrics that are meaningful to a genomic diagnostic environment. This paper presents a three-tier infrastructure that is currently being used to analyze an individual genome and provide available therapeutic options via a clinical report. Our framework utilizes a non-relational variant-centric database that is scaleable to a large amount of data and addresses the challenges and limitations of a relational database system. Our system is continuously monitored via multiple trackers each catering differently to the diversity of users involved in this process. These trackers designed in analytics web-app framework provide status updates for an individual sample accurate to a few minutes. In this paper, we also present our outcome delivery process that is designed and delivered adhering to the standards defined by various regulation agencies involved in clinical genomic testing.