Abstract 179: Comprehensive genomic profiling of solid tumors for key targeted and immuno-oncology biomarkers using Ion Torrent NGS technology on the Oncomine Comprehensive Assay Plus (OCA Plus)

Comprehensive genomic profiling (CGP) of tumor samples by next-generation sequencing is used to support clinical and translational research into the genetic variants that serve as biomarkers for diagnosis, prognosis and potential therapeutic response. However, as these assays grow in size to meet the expanding demands of users, it is challenging to maintain performance in the face of limited sample input necessitated by small sample volumes and to provide a simple and fast sample to report workflow with limited hands-on time. We, therefore, developed OCA Plus to meet user needs for a large CGP assay with excellent performance.

Gene content was prioritized based on potential clinical relevance and variant prevalence in solid tumors. Over 500 genes were selected including genes in the indication statements of approved drug labels, clinical guidelines, and in the enrollment criteria of clinical trials. In addition, driver genes were selected in key pathways including DNA repair and immune checkpoint response. Amplicon design strategies were optimized accordingly for key hotspots, full coding sequences or copy number variation (CNV). The assay used Ion AmpliSeq™ technology with manual library preparation or automated templating on the Ion Chef™ System and sequencing on the Ion GeneStudio™ S5 platform. Twenty ng of purified DNA was routinely used as input. An automated tumor-only workflow for variant calling and sample quality reporting was provided within Ion Reporter™ Software. Streamlined access to reporting of variant relevance was enabled by Oncomine™ Reporter.

In development studies of cancer cell line and formaldehyde-fixed, paraffin-embedded (FFPE) tumor samples, the assay displayed excellent uniformity (98% and 94%, respectively). Detection of single nucleotide variants and indels in cell lines and FFPE samples showed >95% sensitivity and PPV. Detection of CNV gain and loss in cell lines and FFPE samples showed >95% sensitivity and PPV. Assessment of tumor mutational burden (TMB) using publicly available whole-exome cancer sequencing data as well as test cell lines and FFPE samples showed high concordance with whole exome sequencing (R2 > 0.90). MSI sensitivity and specificity was >95% as tested using a diverse set of tumor samples. Targeted fusions were reported with 100% sensitivity and specificity when tested with commercially available controls. Total time from purified DNA to end of sequencing was < 2 days with < 3 hours of hands-on time and the time from post-sequencing to report generation was < 2 hours.

Oncomine Comprehensive Assay (OCA Plus) was developed to support CGP and routine clinical research in oncology. The assay design and informatics workflow were optimized to support low input and rapid sample-to-report turn-around time, which will accelerate clinical and translational research.

Citation Format: Vinay Mittal, Jennifer Kilzer, Dinesh Cyanam, Janice Au-Young, Santhoshi Bandla, Gary Bee, Sameh El-Difrawy, Aren Ewing, Rajesh Gottimukkala, Mohit Gupta, Nickolay Khazanov, Anelia Kraltcheva, Amir Marcovitz, Scott Myrand, Rose Putler, Yu-Ting Tseng, Warren Tom, Cristina Van Loy, James Veitch, Paul Williams, Elaine Wong-Ho, Huimin Xie, Chenchen Yang, Zheng Zang, Seth Sadis. Comprehensive genomic profiling of solid tumors for key targeted and immuno-oncology biomarkers using Ion Torrent NGS technology on the Oncomine Comprehensive Assay Plus (OCA Plus) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 179.

Abstract 3492: A targeted semi-conductor based next-generation sequencing (NGS) test to characterize microsatellite instability in FFPE tumor samples

Microsatellite instability (MSI) arises from defects in the mismatch repair (MMR) system and is associated with hypermutability of short DNA sequence repeats. Defects in MMR are observed in diverse cancer types but are common in colorectal, gastric and endometrial cancers. MSI testing is increasingly important for patient management. For example, in diverse cancer types, MSI is associated with favorable response to immune checkpoint inhibitors. The mainstay of MSI testing has been PCR/fragment analysis or IHC to monitor loss of expression of MMR proteins. Although generally robust, these methods are single biomarker tests that may consume limited biopsy samples. For this reason, MSI testing has been recently incorporated into NGS tests. However, targeted amplicon based NGS tests for MSI that consume limited sample input and provide fast turn-around time remain an unmet need. Herein, we describe a targeted NGS-based method to assess MSI that leverages Ion AmpliSeq™ or Ion AmpliSeq™ HD multiplex PCR and Ion GeneStudio™ S5 next-generation sequencing. The test is comprised of diverse microsatellite markers including mono- and di-nucleotide repeats that range from 10 to 40 bp. A novel algorithm was developed that leverages the unique signal processing properties inherent in semi-conductor sequencing and workflows were developed for tumor only samples as well as paired tumor-normal samples. The test provides results for individual microsatellites and generates an MSI score for the sample. The performance of the assay was verified over a large cohort of colorectal, gastric and endometrial cancer samples with MSI status independently assigned by orthogonal on-market tests. The MSI panel can be used by itself or integrated into larger targeted sequencing panels. MSI tests that leverage the inherent advantages of targeted semiconductor sequencing, low sample input and fast turn-around time, will support expanded research opportunities into the association of MSI with other targeted alterations and help elucidate the interaction of MSI, DNA repair defects, and the response to immune checkpoint inhibition.

Citation Format: Anelia Kraltcheva, Sameh El-Difrawy, Asha Kamat, Janice Au-Young, Simon Cawley, Seth Sadis. A targeted semi-conductor based next-generation sequencing (NGS) test to characterize microsatellite instability in FFPE tumor samples [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3492.