Key Considerations for Selection and Application of Targeted Sequencing Panels in Precision Oncology

From Hotspot Detection to Pan-Cancer Coverage: Understanding Targeted Sequencing Panels

A targeted sequencing panel refers to a technical approach that enriches and performs high-throughput sequencing on a predefined set of genes or genomic regions. Compared with whole-exome or whole-genome sequencing, a panel concentrates sequencing resources on target regions of clinical or research interest, enabling higher coverage depth at lower data output, and is generally used for the detection of somatic mutations, copy number variations, fusion genes, and specific structural variants. In precision oncology, targeted sequencing panels have been widely used to assist molecular subtyping, provide references for targeted therapy, analyze prognosis-related markers, and dynamically monitor resistance mechanisms.

The core value of a targeted sequencing panel lies not in a simple increase in the number of genes, but in the degree of match between the gene list and the intended use. A well-designed panel should select genes based on authoritative databases, guideline consensus, and the level of evidence for drug targets, and should clearly define whether it covers key exons, hotspot regions, promoters, or fusion breakpoints. When selecting a panel, users should first define the application scenario: whether it is for companion diagnostic reference in newly diagnosed patients, for resistance monitoring after treatment, or for research exploration. Different scenarios differ in requirements for gene scope, sample type, reporting turnaround time, and depth of data analysis.

Impact of Sample Types and Library Construction Strategies on Test Results

Common samples for tumor targeted sequencing panels include formalin-fixed paraffin-embedded tissue, fresh frozen tissue, pleural and ascitic fluid, and plasma cell-free DNA. For formalin-fixed paraffin-embedded samples, attention should be paid to the degree of nucleic acid fragmentation and deamination damage, and molecular tags are often introduced during library construction to reduce background errors; plasma cell-free DNA samples impose higher requirements on the sensitivity and specificity of low-abundance mutation detection. Before choosing a panel, its applicable sample types, minimum nucleic acid input, library conversion efficiency, and reproducibility, among other performance indicators, should be confirmed.

Library construction strategies can be divided into amplicon-based and hybridization capture-based methods. The amplicon-based method is relatively simple to perform and has a fast turnaround, but it depends strongly on target region design and may be affected by variants in primer binding regions; the hybridization capture-based method is more suitable for larger regions or scenarios requiring simultaneous detection of fusions and copy number variations, but the workflow is more complex. Users can weigh the options based on sample number, target region size, and laboratory conditions, and need not pursue a single approach.

Performance Validation and Report Interpretation Are Important Dimensions in Panel Selection

Before a targeted sequencing panel is put into practical use, analytical performance validation is generally required, including accuracy, precision, analytical sensitivity, analytical specificity, and reportable range. Laboratories should pay attention to whether the manufacturer provides complete validation documentation, or conduct supplementary validation themselves using reference materials and residual clinical samples. Regarding report interpretation, attention should be paid to variant annotation rules, evidence levels, the calculation methods for indicators such as tumor mutational burden, and whether the report template clearly distinguishes tiers such as variants with clear clinical significance, potential clinical significance, and uncertain significance.

Confirm whether the genes and regions covered by the panel match the clinical needs of the institution;

Understand the applicable sample types and nucleic acid input requirements;

Review performance validation data and external quality assessment performance;

Evaluate version management of the bioinformatics analysis pipeline and support for report interpretation.

Overall, targeted sequencing panel selection is a comprehensive decision that combines intended clinical use, laboratory capability, and quality management. Reasonable selection and continuous validation help obtain stable and traceable test results, providing valuable molecular information for precision oncology.