Twist Bioscience Corporation, a company to offers a synthetic DNA using a silicon platform, has launched the Twist cfDNA Pan-cancer Reference Standards, a high-quality standardized control for use in the development and continuous monitoring of liquid biopsy tests to detect cancer from blood samples.
Liquid biopsy tests, which rely on NGS-based circulating tumor DNA (ctDNA) analysis, are a promising and growing area in clinical oncology. Liquid biopsy assays can accurately identify a single tumor variant in the presence of thousands of healthy cells. The most sought-after applications in the ctDNA field include early detection of disease, personalization of therapy, monitoring response to therapy, and monitoring for relapse of disease. Developing and standardizing these ultra-sensitive yet accurate ctDNA-based assays is paramount to ensure the resulting analysis from the test informs clinical decisions reliably.
“As the number of clinical validations of liquid biopsies increase, a true ctDNA pan-cancer reference standard, beyond the few variants that are widely available today, will increase liquid biopsies’ accuracy in detecting specific oncogenes and variants,” says Florian Battke, director of development at CeGaT GmbH. “There is an obvious benefit of using a synthetic approach like the Twist ctDNA standards, as they are very high quality and closely mimic the properties of real samples without the instability.”
The Twist cfDNA Pan-cancer Reference Standards material consists of synthetically designed variant sequences that mimic ctDNA combined with background DNA that is derived from, and closely mimics, human-derived cell-free DNA (cfDNA).
This reference standard can be used by researchers to assist in the development of liquid biopsy assays to establish the analytical limit of detection (LoD) for specific cancer variants and as a control to track the quality of an NGS assay workflow to ensure the fidelity of the assay process.
The Twist cfDNA Pan-cancer Reference Standards can be used within the liquid biopsy workflow, which includes Twist Library Preparation Kit and the Twist Mechanical Fragmentation Kit, for maximum efficacy and provides a large and diverse number of clinically relevant variants, combining best in class methods for variant synthesis with unrivaled control over the specific target allele frequencies in a format which closely mimics the size distribution and fragmentation profile of cfDNA. In contrast, traditional reference standards are limited in the number and variation of variants and typically use cell line-derived DNA which can carry unwanted sequence variations and variable fragment length.
“Building on the success of our SARS-CoV-2 positive controls that are now used in COVID-19 tests worldwide, we believe having precise standard cancer reference controls that can be used in a validated workflow will be a gamechanger to confirm clinical insights from genetic information,” says Emily Leproust, CEO and co-founder of Twist Bioscience. “While it is possible to create cell-based controls specific to each test, using a robust, precise control set that detects variation in test assays will be pivotal in both development and ongoing monitoring of a wide variety of liquid biopsy assays.”
Applying the right reference materials is essential to benchmark the complexity and biological content of DNA found in liquid biopsy samples for assay development and validation. The Twist ctDNA reference material contains over 400 variants, including SNVs, indels, fusions and structural variants, as well as more than 140 clinically relevant variants. All variants are offered with a unique tiling design, which accurately mimics the pattern of naturally derived ctDNAs. All of these features make the Twist ctDNA reference a high-quality standard for the ctDNA variants that cancer liquid biopsy assays are designed to detect.
To demonstrate the limit of detection (LoD) of an ultra sensitive NGS-based liquid biopsy assay, using an accurately quantified ctDNA control is key. Twist’s silicon platform provides an advantage by specifically writing individual variants of interests, thus preventing any interference caused by contaminants derived from cell culture-based methods. Twist’s ctDNA reference material is also well-characterized and quantified, using industry-standard and proprietary methods (NGS, ddPCR, and fluorescence-based quantification).
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