Diagnostic Precision

A SeraCare blog focused on precision medicine and advanced clinical diagnostics

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How to resolve the challenges of MRD?

Category: NGS, ctDNA, cfDNA, reference materials, MRD

Posted by Yves Konigshofer, PhD on Oct 7, 2020
  This is part 2 of 2 of the MRD blog post. (Click here for part 1). In this section, we will discuss how to overcome some of the most common challenges of MRD testing. Overcoming the Challenges In order to mitigate sequencing errors, methods using Molecular Barcodes (MBCs), Unique Molecular Identifiers (UMIs), etc. (which are essentially all the same) may be used, where each starting molecule is sequenced many times. The MBCs are then used to generate consensus sequences from sequences that were likely obtained from the same starting molecule. The assumption is that errors appear due to somewhat stochastic processes and that the consensus sequences will likely be correct. This requires many observations of the same starting molecule, so it will be recommended to generate 10-fold more sequences than there are molecules. Therefore, with 8,000 genomic equivalents, we might want to target a sequencing depth of 80,000. This is a reason why using 10-fold more input ccfDNA may not necessarily be a good thing (in addition to having to obtain a 10-fold larger liquid biopsy) since we may have to increase sequencing depth accordingly to 800,000, which could increase the cost of sequencing 10-fold, which could reduce the likelihood for payment and running the assay profitably.
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So, you want to monitor Measurable Residual Disease? What are the challenges?

Category: NGS, ctDNA, cfDNA, reference materials, MRD, Minimal Residual Disease

Posted by Yves Konigshofer, PhD on Oct 1, 2020
Part 1 of 2   Background Measurable Residual Disease (MRD) monitoring – for purposes of this blog – will be the act of looking for somatic variants in a liquid biopsy sample by analyzing circulating cell-free DNA (ccfDNA). This is done to monitor the disappearance of a metastatic solid tumor during treatment and to follow any future reemergence of that cancer. Analyzing ccfDNA assumes that circulating tumor DNA (ctDNA) will be present, and the median ctDNA frequency in patient samples across cancers seems to be around 0.5 to 1 %. Thus, the median variant allele frequencies (VAFs) of the somatic variants will start around this range, and the goal of MRD monitoring is to be able to detect them at much lower VAFs. This can be challenging and if we are going to design an assay for MRD monitoring, then we need to be aware of them and overcome them.
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Newly Published Multi-Laboratory Study Provides Utility and Validation of the Use of ctDNA Reference Standards

Category: ctDNA, cfDNA

Posted by Russell Garlick, PhD on May 30, 2019
I am pleased to share findings from a newly published peer-reviewed study with foundational circulating tumor DNA (ctDNA) pre-analytical and analytical testing in multiple technologies and assay chemistries. The study, “Multi-laboratory Assessment of a New Reference Material for Quality Assurance of Cell-Free Tumor DNA Measurements,” was just published in The Journal of Molecular Diagnostics (He, Stein et al. 2019).
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Precision Medicine and Clinical Labs: AACR Dinner Seminar Recap

Category: clinical genomics, cfDNA, AACR

Posted by Trevor Brown on Apr 15, 2019
One of the core aims of precision medicine is to provide a more tailored approach to disease diagnosis, therapy selection, and patient monitoring to improve the overall quality of life for patients with disease. Indeed, this aim has been at the heart of the high interest and study of the potential of liquid biopsies to improve patient care in earlier detection of cancer, treatment, and surveillance.
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Customer Data: Use of Seraseq ctDNA Reference Samples to Validate Detection of Low Frequency Variants in a cfDNA-based NGS Lung Cancer Panel

Category: ctDNA, SeraSeq, AMP, cfDNA, Lung Cancer

Posted by Omo Clement, PhD on Feb 14, 2019
At the recently-concluded 2018 AMP Meeting, researchers at the New York Presbyterian Hospital (NYPH) and Weill Cornell Medical Center (WCMC) presented a poster1 on the validation of an Oncomine™ cell-free DNA Lung Assay using ctDNA NGS standards developed by SeraCare (Seraseq® ctDNA v2 Reference Materials),2
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Two Must-See Liquid Biopsy Poster Videos From AMP 2018

Category: ctDNA, SeraSeq, AMP, liquid biopsy, cfDNA

Posted by Sam Blier on Dec 7, 2018
  Of the many fantastic posters presented at AMP’s Annual Meeting in San Antonio, two concerning NGS-based liquid biopsy assays stood out. Both presenters described how their organizations are working to reliably detect pathogenic variants at extremely low allele frequencies – efforts critical to the clinical adoption of NGS-based liquid biopsy assays.
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Three liquid biopsy problems solved by the most patient-like ctDNA reference materials

Category: ctDNA, cfDNA, reference materials

Posted by Dale Yuzuki on Jul 24, 2017
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.
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