Study of the Clearance of Minimal Residual Disease Measured at the End of First-line Treatment in Patients Treated for B-cell Lymphoma or Hodgkin Lymphoma

Over the past decade, molecular biology methods known as "liquid biopsy" tools have emerged to identify tumor genotypes without a traditional biopsy, using blood samples and sequencing of circulating tumor DNA (ctDNA). Evidence supporting ctDNA's ability to perform comprehensive tumor genotyping, serving as an accurate reflection of the tumor genotype, has been well-documented in the literature. Two key aspects of the clinical relevance and routine applicability of ctDNA are currently under investigation:

The potential to measure and monitor the clearance of minimal residual disease (MRD) during and after treatment, which heavily depends on the detection limit and sensitivity of the analytical method.

The ability to deliver ctDNA analysis results to clinicians in real time, within timelines compatible with patient decision-making.

At Rouen, the investigators now use a method based on Unique Molecular Identifiers (UMIs), a type of molecular barcode that provides increased precision during sequencing. These molecular barcodes are short sequences used to uniquely label each DNA molecule in a sample library, minimizing false positives caused by random sequencing errors. By incorporating individual barcodes into each original DNA fragment, true variants in the original sample can be distinguished from errors introduced during library preparation, target enrichment, or sequencing.

The investigators have developed a new Next Generation sequencing (NGS) panel dedicated to ctDNA analysis using UMIs, encompassing 101 genes and 133 Kb of sequencing regions with phased variants on an Illumina® pipeline.