Clinical genomics laboratories are increasingly looking to liquid biopsy cancer assays to complement their current solid tumor assays. Compared to their solid tumor assay counterparts, circulating tumor DNA (ctDNA) assays offer a different set of challenges to consider for clinical labs. One of the most important of which, is to develop a set of reagents that are appropriately validated to determine the critical performance of the assay across many parameters. The ctDNA targets of liquid biopsy assays are typically at much lower allelic frequencies and require a robust and reproducibly designed assay to consistently detect these important variants.
SeraCare’s new Seraseq™ Circulating Tumor Reference Materials
"The most effective ways to use QC data to monitor the health of your NGS assay."
Previously, we wrote about some of the Quality Control challenges that clinical laboratories performing Next Generation Sequencing (NGS) face towards ensuring their assays are safe and effective for guiding medical management decisions. Reliable access to high quality reference materials is necessary to help overcome these challenges; however, it is not sufficient. Insights that reference materials provide into the health of an NGS assay are only as good as laboratories’ ability to use their QC data effectively.
With limited time and resources to collect, organize, access, and analyze QC metrics, laboratories may frequently rely on reference materials as binary indicators of Pass/Fail: As long as the expected endpoint results are obtained, an assay is considered to be performing well. The drawback of this approach is that it is reactive, rather than proactive: A sufficient number of failures must occur within a given timeframe before a troubleshooting investigation is performed. By the time a problem is recognized, resources have been wasted and turnaround times (TAT) delayed; in some cases, fidelity of patient results may even have been put at risk. Additional time and costs are then incurred as the investigation proceeds.
Specimen analysis by NGS yields a wealth of information in addition to endpoint variant calls that is indicative of assay performance. Data such as nucleic acid quantity and quality at different steps throughout the workflow (PDF) and sequencing library characteristics are generated every time a reference material is tested. However, these data must be carefully tracked and trended to allow use as highly informative QC parameters. For clinical laboratories whose primary focus is on patient testing and reporting, granular QC metrics may not be captured and reviewed as part of routine test monitoring.
“Ensure NGS-based tests for Personalized Medicine are safe and effective for guiding medical management decisions”
Since the introduction of the GS20 in 2005 by 454 Life Sciences, Next Generation Sequencing (NGS) has found many applications in clinical diagnostics. As a result of this transition from the long-held gold standard, Sanger sequencing, the primary challenge for clinical laboratories has shifted from data acquisition to ensuring these tests are safe and effective for guiding medical management decisions.
Many laboratories struggle to gain a thorough understanding of the analytic performance characteristics of their NGS tests. The difficulty arises from the fact that these assays are comprised of highly complex, fragmented workflows, and have many different intended uses. However, across the various practices currently used for NGS assay development, validation, and performance monitoring, there is a common goal: results must be as accurate, precise, and consistent as possible.
The distinction between accuracy and precision.
If you took a university introductory statistics course, you may have learned the distinction between accuracy and precision. It may likely have been presented with an archery analogy, where ‘Accurate’ was represented by arrows loosely clustered around the target’s bull’s-eye, ‘Precise’ was shown as a tight grouping displaced from the center, and ‘Accurate and Precise’ was depicted as what every archer aims for, a tight grouping directly at the bull’s-eye. Suddenly, words that are used interchangeably in everyday conversation took on dramatically different meanings.
Important information for assay development and review by the FDA
The presentations during the FDA-AACR Liquid Biopsies in Oncology Drug and Device Development Workshop on July 19, 2016 included several important pieces of information that will likely guide the development of assays and their review by the FDA.
After 17 months of deliberations since its first open meeting February 20, 2015 on NGS IVD assay oversight, the U.S. Food and Drug Administration (FDA) issued DRAFT guidance for Stakeholders and FDA staff. The document “Use of Standards in FDA Regulatory Oversight of Next Generation Sequencing (NGS)-Based In Vitro Diagnostics (IVDs) Used for Diagnosing Germline Diseases” was published online on July 6, 2016. This document (PDF located here) is for analytical validity and not for clinical validation.
Diagnosing inherited disease, processing FFPE samples, state-of-the-art oncology in North Carolina, and developments in circulating tumor DNA technology
We are living through a time of rapid change in the clinical genetics laboratory, though at times it may appear that change doesn’t occur fast enough given the challenges within the existing healthcare system. At the recent Molecular Medicine Tri-Conference held in San Francisco March 7 through 11 2016, here are a few summary highlights of the conference.
Poster Titled “New Technical Approach to Construct ctDNA Materials for use in Characterizing, Developing and Validating Plasma Assays”, available for download
The Keystone Symposia is an organization with 44 years of history on specialized topics across the fields of molecular and cellular biology. This week in Banff, Alberta, Canada is a Keystone Symposia conference called The Cancer Genome, along with a joint meeting on Genomics and Personalized Medicine. Their Twitter description (@KeystoneSymp) describes the Keystone organization as “A catalyst for accelerating life science discovery and connecting scientists within and across disciplines at symposia worldwide”.
Laboratory-developed tests are in the spotlight by the US Food and Drug Administration
Recently, the FDA upped the ante in the ongoing debate over its desire to regulate laboratory developed tests (LDTs) with the release of a report detailing the ‘real and potential harms to patients and to public health’ arising from LDTs. This debate has been heating up for several years now—not coincidentally with the emergence of precision medicine and the rapid adoption of data-intensive tools such as Next Generation Sequencing (NGS) and the growing pipelines of targeted therapeutics. One might argue that the horse has already left the barn and the FDA are trying to corral it back in.
A handy infographic to compare the first-generation (Sanger) and next-generation sequencing (NGS) technologies
It is hard to believe that next-generation sequencing has only been around for a little over ten years, but has had a profound impact on many frontiers of basic and applied genetics. To contrast the first-generation (Sanger sequencing by capillary electrophoresis) and the next-generation sequencing (NGS) approaches, we provide you with this infographic.