EGFR T790M detection in formalin-fixed paraffin-embedded tissues of patients with lung cancer using RNA-based in situ...

Area of Science:

• Oncology
• Molecular Diagnostics
• Genetics

Background:

• Drug resistance to Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors (EGFR TKIs) necessitates T790M mutation detection in lung cancer patients.
• Accurate T790M detection is crucial for identifying patients eligible for third-generation EGFR TKIs like osimertinib.
• Current diagnostic methods require sufficient tumor tissue, often necessitating invasive biopsies.

Purpose of the Study:

• To evaluate the feasibility of a novel in situ analysis technique utilizing RNA target sequences for EGFR T790M detection in lung cancer.
• To assess the diagnostic performance of the BaseScope T790M assay compared to established methods.

Main Methods:

• Analysis of 28 formalin-fixed paraffin-embedded (FFPE) lung adenocarcinoma samples using the BaseScope T790M in situ hybridization technique.
• Comparison of BaseScope T790M results with the gold standard Scorpions ARMS assay for EGFR gene mutation testing.
• Preliminary evaluation of the sensitivity and specificity of the BaseScope T790M assay.

Main Results:

• The BaseScope T790M assay demonstrated 100% sensitivity and 100% specificity in the evaluated cohort.
• The assay successfully detected T790M mutations in FFPE samples, with an average positive cell proportion of 35.78% in positive cases.
• Results were consistent with the Scorpions ARMS assay, confirming the reliability of the novel technique.

Conclusions:

• The BaseScope T790M assay is a feasible and accurate method for evaluating EGFR T790M mutations directly on FFPE slides.
• This technique integrates molecular findings with histomorphological information, potentially simplifying the diagnostic workflow.
• BaseScope T790M assay shows significant clinical utility and warrants further validation in larger patient cohorts.