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Supplemental Digital Content is available in the text., Targeted therapy combined with companion diagnostics has led to the advancement of next-generation sequencing (NGS) for detection of molecular alterations. However, using a diagnostic test to identify patient populations with low prevalence molecular alterations, such as gene rearrangements, poses efficiency, and cost challenges. To address this, we have developed a 2-step diagnostic test to identify NTRK1, NTRK2, NTRK3, ROS1, and ALK rearrangements in formalin-fixed paraffin-embedded clinical specimens. This test is comprised of immunohistochemistry screening using a pan-receptor tyrosine kinase cocktail of antibodies to identify samples expressing TrkA (encoded by NTRK1), TrkB (encoded by NTRK2), TrkC (encoded by NTRK3), ROS1, and ALK followed by an RNA-based anchored multiplex polymerase chain reaction NGS assay. We demonstrate that the NGS assay is accurate and reproducible in identification of gene rearrangements. Furthermore, implementation of an RNA quality control metric to assess the presence of amplifiable nucleic acid input material enables a measure of confidence when an NGS result is negative for gene rearrangements. Finally, we demonstrate that performing a pan-receptor tyrosine kinase immunohistochemistry staining enriches detection of the patient population for gene rearrangements from 4% to 9% and has a 100% negative predictive value. Together, this 2-step assay is an efficient method for detection of gene rearrangements in both clinical testing and studies of archival formalin-fixed paraffin-embedded specimens.

Anaplastic lymphoma kinase (ALK) fusion is a common mechanism underlying pathogenesis of non-small cell lung carcinoma (NSCLC) where these rearrangements represent important diagnostic and therapeutic targets. In this study, we found a new ALK fusion gene, SEC31A-ALK, in lung carcinoma from a 53-year-old Korean man. The conjoined region in the fusion transcript was generated by the fusion of SEC31A exon 21 and ALK exon 20 by genomic rearrangement, which contributed to generation of an intact, in-frame open reading frame. SEC31A-ALK encodes a predicted fusion protein of 1,438 amino acids comprising the WD40 domain of SEC31A at the N-terminus and ALK kinase domain at the C-terminus. Fluorescence in situ hybridization studies suggested that SEC31A-ALK was generated by an unbalanced genomic rearrangement associated with loss of the 3'-end of SEC31A. This is the first report of SEC31A-ALK fusion transcript in clinical NSCLC, which could be a novel diagnostic and therapeutic target for patients with NSCLC.

RNA interference screening using pooled, short hairpin RNA (shRNA) is a powerful, high-throughput tool for determining the biological relevance of genes for a phenotype. Assessing an shRNA pooled screen’s performance is difficult in practice; one can estimate the performance only by using reproducibility as a proxy for power or by employing a large number of validated positive and negative controls. Here, we develop an open-source software tool, the Power Decoder simulator, for generating shRNA pooled screening experiments in silico that can be used to estimate a screen’s statistical power. Using the negative binomial distribution, it models both the relative abundance of multiple shRNAs within a single screening replicate and the biological noise between replicates for each individual shRNA. We demonstrate that this simulator can successfully model the data from an actual laboratory experiment. We then use it to evaluate the effects of biological replicates and sequencing counts on the performance of a pooled screen, without the necessity of gathering additional data. The Power Decoder simulator is written in R and Python and is available for download under the GNU General Public License v3.0.

Introduction: Deregulation of the proto-oncogene, MET, confers an aggressive phenotype in a variety of human cancers, promoting proliferation, invasive growth and angiogenesis. MET deregulation can be driven by gene amplification, overexpression, exon 14 skipping, gene fusions and single nucleotide variants (SNVs), such as kinase-activating point mutations. MET is a target of intensive drug development efforts, although the various mutated forms of MET exhibit unique drug sensitivities. Therefore, detection of these mutations has an important role in the development of drugs targeting MET, and has the potential to guide treatments for cancers driven by MET deregulation. Next-generation sequencing (NGS) enables comprehensive detection of all mutation types from whole genomes and transcriptomes. However, low detection sensitivity, high input requirement and high costs render these approaches impractical for routine detection of mutations from low-input clinical sample types. We developed a targeted NGS assay based on Anchored Multiplex PCR (AMP™) to detect all types of mutations driving MET deregulation from a single sample. Methods: AMP only requires a single gene-specific primer for amplification, enabling open-ended capture of DNA and cDNA fragments for NGS-based detection of known and unknown mutations. We developed AMP-based Archer® VariantPlex™ and FusionPlex® library preparation assays to detect mutations from DNA and RNA, respectively. AMP probes were designed to cover the MET gene for detection of copy numbers variants (CNVs) and SNVs from DNA, and known and novel fusions, exon skipping and expression levels from RNA. Results: We show that the VariantPlex assay enables NGS-based detection of MET amplifications from DNA in concordance with FISH results. Further NGS analysis of RNA from the same sample using the FusionPlex assay revealed the resulting overexpression of MET. We also demonstrate that AMP-enabled open-ended capture of cDNA fragments allows for reliable detection of exon 14 skipping in FFPE samples and in cells, consistent with RT-PCR results. Parallel analysis of DNA from the cell samples revealed splice site mutations that have been previously reported to drive exon 14 skipping. Furthermore, this open-ended capture also permitted identification of a novel GTF2I:MET gene fusion in a patient-derived xenograft model. Finally, we detected an kinase-activating point mutation in MET, p.Y1253D, by analysis of genomic DNA with the VariantPlex NGS assay. Conclusions: These results show that AMP-based VariantPlex and FusionPlex Assays enable comprehensive detection of multiple mutation types from low-input clinical sample types, such as FFPE specimens. As MET deregulation can be driven by many different genetic aberrations, this allows for NGS-based characterization of MET deregulation from a single sample. Citation Format: Brian A. Kudlow, Josh Haimes, Marc Bessette, Namitha Manoj, Laura M. Griffin, Danielle Murphy, Robert Shoemaker, Jason Amsbaugh, Joshua Stahl. Comprehensive detection of all major classes of MET deregulation by Anchored Multiplex PCR and next-generation sequencing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 742. doi:10.1158/1538-7445.AM2017-742

Introduction Acute myeloid leukemia (AML) oncogenesis is thought to require multiple somatic mutations in a "two-hit" process to 1) increase proliferation and 2) prevent maturation of myeloid cells. While FLT3 and KIT mutations are associated with increased proliferation, NPM1, CEBPA and several other mutations can be associated with maturation inhibition. The most common mutations in AML are internal tandem duplications (ITDs) in FLT3, which are detected in more than 20% of pediatric and adult AML cases and are associated with an aggressive phenotype. As FLT3-ITD expressed kinases are sensitive to tyrosine kinase inhibitors, they are of considerable interest for the development of novel AML treatments. Capillary gel electrophoresis can detect ITDs but cannot be easily coupled with assays to detect other mutation types common in AML. Next-generation sequencing (NGS)-based methods enable comprehensive detection of multiple mutation types. However, detection of ITDs by NGS is particularly challenging, in part because of their highly variable nature and the difficulties of mapping repeated sequences to a wild-type reference. Anchored Multiplex PCR (AMP) is a target enrichment strategy for NGS that uses molecular barcoded adaptors and gene-specific primers, permitting open-ended capture of DNA fragments from a single end. We present an approach based on AMP technology and a novel bioinformatics algorithm to detect ITDs in FLT3 as well as other mutation types common in AML. Methods We developed a library preparation assay for NGS to detect FLT3-ITDs as well as other mutations relevant in AML from genomic DNA extracted from clinical samples. We designed AMP probes to cover the commonly mutated juxtamembrane domain and tyrosine kinase domain 1. We further developed a novel de novo sequence assembly algorithm based on over 2000 in silico datasets representing a large range of known ITDs. Results In silico datasets enabled optimization of our sequencing data analysis algorithm, resulting in the detection of over 98% of in silico ITDs with no false positives. The AMP library preparation assay in conjunction with the optimized analysis algorithm enabled sensitive NGS-based detection of ITDs in 16 AML-positive blood samples. These results were consistent with results obtained from standard capillary gel electrophoresis. In addition, point mutations in the TKD of FLT3 and insertions in NPM1 exon 11 were detected in 2/7 and 5/7 FLT3-ITD positive blood samples. Conclusions Our data show that AMP enables accurate NGS-based detection of FLT3-ITDs from clinical DNA samples. As this approach can detect multiple mutation types from a single sample, our AMP library preparation coupled with our NGS analysis algorithm enables simultaneous detection of multiple mutations relevant in AML. Disclosures Van Deusen: ArcherDX, Inc.: Employment. Bessette:ArcherDX, Inc.: Employment. Johnson:ArcherDX, Inc.: Employment. Berlin:ArcherDX, Inc.: Employment. Banos:ArcherDX, Inc.: Employment. Griffin:ArcherDX, Inc.: Employment. Reckase:ArcherDX, Inc.: Employment. Stahl:ArcherDX, Inc.: Employment. Licon:ArcherDX, Inc.: Employment. Kudlow:ArcherDX, Inc.: Employment.

FLT3 internal tandem duplications (ITDs) are found in > 20% of pediatric and adult acute myeloid leukemia (AML) cases and are generally associated with a poor prognosis. Nevertheless, detection of FLT3-ITDs presents a challenge to NGS-based approaches, as many variant callers fail to identify the highly variable repeated sequences associated with FLT3-ITDs. We have developed a novel targeted assay, the Archer™ VariantPlex™ Core AML Panel, that utilizes Anchored Multiplex PCR (AMP™) with probes in multiple locations proximal to exons 13, 14, and 15 of FLT3. These exons encompass the commonly mutated juxtamembrane domain and tyrosine kinase domain 1. This panel yields high-complexity, dual-strand coverage of known FLT3-ITD locations. Because AMP probes, unlike traditional PCR probes, function independently of each other, we are able to produce multiple overlapping “snapshots” of the region of interest, thereby enhancing the ability to confidently identify complex mutation types. The sequenced reads are assembled using a novel de novo assembly algorithm in the Archer Analysis bioinformatics pipeline, in which the resulting consensus is annotated and events that involve FLT3 exons 13 14 or 15 are marked as FLT3 abnormalities. In order to assess Archer Analysis and the VariantPlex Core AML panel, we tested it on >20 patient-derived samples with known FLT3-ITDs. In addition, we generated over two thousand in silico datasets, representing the spectrum of known ITDs, to further test our panel design and analysis algorithm. Each in silico dataset was constructed to simulate reads originating from probes in VariantPlex Core AML Panel. This methodology permitted rigorous optimization of both the VariantPlex Core AML Panel and the analysis algorithm. The VariantPlex Core AML Panel, in conjunction with our novel detection algorithm, showed both exceptional sensitivity and specificity in the detection of FLT3-ITDs. FLT3-ITDs were successfully identified in all patient samples tested, and no false positives were detected. Our in silico datasets showed similarly high sensitivity and specificity. These data indicate that AMP libraries targeting the FLT3-ITD region are ideal for the detection of this complex mutation type, largely because of the overlapping and anchored read structure. Therefore, the Archer VariantPlex Core AML panel, in conjunction with Archer Analysis represents a reliable platform for the detection of FLT3-ITDs, in addition to other mutations commonly found in AML. Citation Format: Marc Bessette, Benjamin Van Deusen, Michael Banos, Laura Johnson, Aaron Berlin, Erik Reckase, Joshua Stahl, Abel Licon, Brian Kudlow. NGS-based detection of FLT3-ITDs with Anchored Multiplex PCR. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3618.

Copy number variations (CNV) impact more of the cancer genome than all other mutation types combined. Recent advances in next-generation sequencing (NGS) have enabled simultaneous detection of CNVs and other somatic mutations from FFPE-derived samples, but NGS-based detection of low level CNVs (ie 2-3x) remains challenging. Nucleic acid from FFPE is a common starting material for NGS-based cancer genotyping; however, this material is often of low complexity due to a variety of factors including limited mass amount, excessive fragmentation, or chemical crosslinking. Current practices often measure input mass, or the nanograms of DNA that are added to a reaction, yet it is input complexity, or the amount of nucleic acid available for NGS library generation, that truly dictates the amount of information that can be recovered from a given sample. Archer™ VariantPlex™ assays are targeted NGS panels that permit simultaneous detection of SNVs, in/dels, and CNVs using Anchored Multiplex PCR (AMP™). Molecular barcoded adapters are ligated to each input molecule prior to any amplification. This permits the unique identification of individual input molecules thus facilitating precise copy number measurements. In addition, AMP enables amplification of highly fragmented FFPE inputs as short fragments are captured between the ligated adapter and the enrichment probe. To determine the effect of input quality on sensitivity of CNV calling we characterized over 150 tumor sample input qualities and their resulting library metrics. In addition we modeled the effect of low tumor cellularity on CNV sensitivity by carrying out dilution experiments of CNV-positive samples into samples of normal copy number. Using Archer VariantPlex assays in conjunction with Archer Analysis, we have successfully detected CNVs as small as 2X in both FFPE and cell line DNA. We found that input nucleic acid quality, as measured by a qPCR-based assay called Archer PreSeq™ DNA QC, strongly impacted the sensitivity of CNV calling. Assessment of input complexity using the PreSeq DNA QC Assay is predictive of limit of detection for CNVs and identifies an input quantity that will result in high quality NGS libraries. Our dilution experiments confirmed the expected relationship between actual and measured copy number in our population-averaging assay. Nucleic acid damage typical of FFPE samples reduces CNV calling sensitivity; however, this loss of sensitivity can be partially mitigated by increasing the input quantity. This corroborates the notion that input complexity is the major driver of information-capture from NGS based assays. Finally, tumor cellularity displays a predictable effect on the measured CNV value. Citation Format: Josh Haimes, James Covino, Namitha Namoj, Elina Baravik, Laura Johnson, Joshua Stahl, Brady P. Culver, Brian Kudlow. NGS-based CNV detection sensitivity is dependent upon nucleic acid input quality. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1381.