• Consensus: ISO-certified ctDNA reference materials vital for assay validation • Experts urge EQAs to include low-frequency variants for clinical relevance • ELBS workshop: Expand ctDNA EQAs to pan-cancer biomarkers and scenarios • Reference materials must mimic cfDNA properties for reliable ctDNA testing • EQAs should assess SNVs, fusions, SCNAs across NSCLC, CRC, and pan-cancer The European Liquid Biopsy Society (ELBS) ctDNA Workshop in 2023 brought together 44 experts from various disciplines to discuss the current status and future needs for reference materials and external quality assessment (EQA) in cancer liquid biopsy assays. The workshop focused on identifying, through presentations, discussion, and polls, key aspects that participants considered important for the design and use of reference materials and EQA schemes in ctDNA testing, which is increasingly used to guide crucial treatment decisions in cancer patients. The experts emphasized the importance of using well-characterized reference materials that closely mimic patient-derived ctDNA in terms of biochemical properties and assay performance, including plasma-like reference materials, multiple serial dilutions, and various input amounts to assess analytical sensitivity and specificity. The workshop participants also highlighted the importance of EQA schemes that include a broad range of clinically relevant genetic alterations, low variant allele frequencies, and cover different cancer types. Overall, the outputs of the workshop provide a snapshot of expert opinions with the ELBS community and are intended to inform ongoing discussions on reference materials and EQA for ctDNA testing, to eventually standardize EQA schemes, support improved assay validation, and ensure high-quality clinical reporting when liquid biopsy is used in routine clinical practice.
Hill et al. (Sun,) studied this question.