Fig. 3

Use cases for ctDNA analysis throughout the cancer patient journey: identification of actionable targets in patients with advanced cancer. A Representation of 3 real-world cases of patients with confirmed progressive disease where liquid biopsy was justified to identify actionable targets. Available clinical patient characteristics and primary tumor biopsy profiling data are displayed in the white box. The last received therapy along with the associated measured radiological response (RECIST 1.1) are in the dark blue box and the specific rationale for ordering a liquid biopsy is listed in the dark green box. Below, a summary of the NGS results from comprehensive genomic profiling (CGP) via the AVENIO ctDNA Expanded Panel are documented, including: tumor fraction in plasma estimated via ichorCNA (%; LOD 3%); clinically relevant and pathogenic somatic copy number alterations (SCNAs) and variants, with variant allele frequency (VAF, %) detected from plasma DNA; non-actionable and variants of unknown significance (VUS). Of particular note is Case 3, which had a relatively high tumor fraction of 21%, but the two pathogenic variants detected had VAFs <1%. As these low allele fractions (KRAS G12A: 0.23%, PTEN N323fs: 0.24%) do not align with the overall tumor content of the sample, these VAFs may indicate subclonality of the alterations or potential sequencing artifacts. For this reason, it would be necessary to confirm their presence with an orthogonal approach using a new blood sample, especially if they were to influence a treatment decision. B Basic decision tree for this use case and the interpretation of detected alterations from liquid biopsy NGS data. The cases in (A) are mapped at the corresponding position that reflects the individual scenario. The critical starting point is the assessment of ctDNA level, i.e. tumor fraction (TF), in plasma, as samples with sufficiently low TF may not yield any detected alterations (Case 2). In such cases, reflex tissue testing is the clinical standard. If the sample has sufficient a ctDNA level, the analyst must rule out potential CHIP or germline variants before moving on to actionability assessment. In some cases, mutations associated with resistance are detected (Case 1), but no therapeutic targets are found. The identification of actionable targets and matching of potential suitable, evidence-based treatments is not a straightforward process and thus should be discussed at a molecular tumor board with oncologists to derive the final treatment decision (Case 3)