Optimizing Mutation and Fusion Detection in NSCLC by Sequential DNA and RNA Sequencing.

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Locally advanced or metastatic non-small cell lung cancer (NSCLC) patients often undergo molecular screening for mutations and fusions.
• Current molecular workup involves multiple tests, risking tissue exhaustion due to emerging targeted therapies.

Purpose of the Study:

• To evaluate the efficiency of targeted RNA next-generation sequencing (NGS) for identifying gene fusions and exon-skipping events in NSCLC.
• To compare parallel (DNA and RNA NGS) versus sequential (DNA NGS followed by RNA NGS) molecular workup strategies.

Main Methods:

• Analyzed stage IV NSCLC cases using both parallel and sequential DNA and RNA NGS workflows.
• Included cytology and microdissected histology samples, primarily core needle biopsies.
• Compared molecular findings between the two workup approaches.

Main Results:

• Identifying an oncogenic driver via DNA NGS allows omitting RNA NGS in most cases, reducing RNA NGS necessity to 53%.
• Tumors from never-smokers showed a higher enrichment of fusions and exon-skipping events (32%) compared to smokers (4%).
• The parallel approach offered a shorter turnaround time (9 days) for never-smokers compared to the sequential approach (15 days).

Conclusions:

• A sequential DNA and RNA NGS strategy is most efficient for smoking-associated NSCLC.
• A parallel DNA and RNA NGS approach is recommended for never-smokers.
• This optimized molecular workup is feasible for small samples, reduces complexity and cost, and adapts to evolving therapeutic targets.