Use of a plasma test for verifying epidermal growth factor receptor gene (EGFR) mutations in fluid samples from...

Area of Science:

• Oncology
• Molecular Diagnostics
• Genetics

Background:

• Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are vital for treating non-small cell lung cancer (NSCLC) patients with specific EGFR mutations.
• Accurate EGFR mutation testing is essential for effective NSCLC treatment selection.

Observation:

• The commercial Cobas EGFR Mutation test v2.0 can analyze both formalin-fixed, paraffin-embedded (FFPE) tissue (FT) and plasma samples (PT).
• In three cases, EGFR mutations were detected in FFPE primary tumor tissue using FT but not in fluid samples (pleural effusion, cerebrospinal fluid).
• Fluid samples are often used for EGFR mutation testing in relapsed patients when primary tumor tissue is unavailable.

Findings:

• The formalin-fixed, paraffin-embedded tissue test (FT) may have limitations in detecting EGFR mutations in fluid samples.
• The plasma test (PT) demonstrated higher sensitivity and successfully detected the same EGFR mutations in fluid samples that were previously identified in FFPE tissue.
• The plasma test (PT) confirmed the presence of EGFR mutations in fluid samples, aligning with results from FFPE tissue testing.

Implications:

• The plasma test (PT) offers a more sensitive method for EGFR mutation detection in fluid samples, particularly for relapsed NSCLC patients.
• Utilizing the more sensitive plasma test (PT) can improve diagnostic accuracy when primary tumor tissue is unavailable.
• These findings highlight the importance of selecting the appropriate EGFR mutation testing method based on sample type to ensure accurate patient stratification for targeted therapy.