ctDNA Sequencing Services

Circulating tumor DNA (ctDNA) is a type of extracellular DNA present in body fluids such as plasma, serum, cerebrospinal fluid, etc. It primarily originates from necrotic or apoptotic tumor cells, extracellular vesicles secreted by tumor cells, and circulating tumor cells. The typical size of ctDNA is in the range of 160-180 base pairs. ctDNA is a subset of cell-free DNA (cfDNA) and constitutes a relatively low proportion (between 0.1% and 1%), making its detection challenging. The maturation of next-generation sequencing (NGS) technology has significantly enhanced the sensitivity and accuracy of ctDNA detection.

Characteristics of Circulating Tumor DNA Sequencing

Convenient Sampling: Non-invasive, real-time, easily accessible multiple times ctDNA analysis is achieved by extracting blood, eliminating the risks and discomfort associated with invasive methods such as biopsies and surgeries for collecting tumor tissue. In the early stages of malignant tumors, alterations in ctDNA content and genes can be detected.

Mature Detection Technology: High sensitivity, high accuracy, low false-positive rate Utilizing NGS for ctDNA detection ensures high sensitivity and accuracy, detecting mutations as low as 0.1%. Compared to other types of tumor markers, ctDNA exhibits higher sensitivity, making it an ideal tumor biomarker.

Comprehensive Detection: Broad Application Range Nearly all tumor cells release DNA fragments into the bloodstream. Consequently, ctDNA reflects the overall status of tumors in the body. Heterogeneity significantly impacts gene testing in tumor tissues, but ctDNA detection mitigates the randomness and locality associated with tumor tissue heterogeneity. This ensures more comprehensive and reliable results for tumor mutations.

Services We Offer

Whole-Genome Resequencing for ctDNA

We provide comprehensive whole-genome resequencing for ctDNA, enabling the analysis of various types of mutations carried by ctDNA, such as single nucleotide polymorphisms (SNPs), insertions and deletions (indels), and large structural variations.

Exome Sequencing for ctDNA

Similar to conventional genomic DNA, a sufficient quantity of ctDNA can undergo exome sequencing to detect variations in coding regions.

Methylation Sequencing for ctDNA

Methylation sequencing for ctDNA is a focal point in research. This includes the detection of methylation sites for individual genes and comprehensive methylation site detection across the entire genome.

Targeted Region Sequencing for ctDNA

Our targeted region panel for ctDNA allows for the detection and analysis of specific target sites. In comparison to whole-genome sequencing, this method provides a more cost-effective solution.

(Elodie Bohers et al,. Pharmaceuticals 2021)

Service Advantages

Comprehensive Service: We offer an all-inclusive service, covering the entire process from ctDNA extraction, library preparation, sequencing, to data analysis.

Ultra-Low ctDNA Input: Our technology allows for sequencing with starting ctDNA amounts as low as 10 ng.

Stringent Quality Control: A rigorous quality control process is implemented at every stage, ensuring high accuracy in the results provided to our clients.

Specialized Bioinformatics Analysis: Our proficient bioinformatics team is equipped to meet the personalized data analysis requirements of our clients.

Sample Requirements

Sample Types: Plasma, serum, or cfDNA from cancer patients.

Plasma is recommended over serum to minimize interference from lymphocyte-derived cfDNA.

Sample Volume: Plasma > 5 mL; Serum > 10 mL; cfDNA > 10 ng.

Plasma Extraction:

Collect whole blood in EDTA anticoagulant tubes, avoiding freezing; store briefly at 2-8℃ before promptly low-temperature centrifugation to obtain plasma.

If low-temperature centrifugation is not possible, use STRECK non-invasive tubes with a proprietary stabilizer for whole blood preservation, allowing room temperature centrifugation.

To eliminate residual cells, plasma should undergo a secondary centrifugation: first at 4℃ at 1600g for 10 minutes, followed by a second centrifugation at 4℃ at 16000g for 10 minutes.

Sample Storage: Freeze plasma and serum samples rapidly in liquid nitrogen and store at -80℃. Avoid repeated freeze-thaw cycles during sample storage.

References

1. Michail Ignatiadis, et al. Liquid biopsy enters the clinic-implementation issues and future challenges. Nat Rev Clin Oncol. 2021 M
2. Ming Chen, Next-generation sequencing in liquid biopsy: cancer screening and early detection. Hum Genomics. 2019 Aug 1;13(1):34.
3. Carolin M Sauer, Longitudinal monitoring of disease burden and response using ctDNA from dried blood spots in xenograft models. EMBO Mol Med. 2022
4. Etienne Giroux Leprieur, Sequential ctDNA whole-exome sequencing in advanced lung adenocarcinoma with initial durable tumor response on immune checkpoint inhibitor and late progression. J Immunother Cancer. 2020
5. Anjui Wu, Genome-wide plasma DNA methylation features of metastatic prostate cancer. J Clin Invest. 2020
6. Jianxia Chen, et al. Design of a Targeted Sequencing Assay to Detect Rare Mutations in Circulating Tumor DNA. Genet Test Mol Biomarkers. 2019