Establishment of a Flow Cytometry Protocol for Binarily Detecting Circulating Tumor Cells with EGFR Mutation

Area of Science:

• Oncology
• Proteomics
• Molecular Diagnostics

Background:

• EGFR mutations in non-small cell lung cancer (NSCLC) predict response to tyrosine kinase inhibitors (TKIs).
• Current EGFR mutation detection requires invasive tumor biopsies.
• Less invasive methods for EGFR mutation profiling are needed, especially using circulating tumor cells (CTCs).

Purpose of the Study:

• To develop and validate a flow cytometry-based proteomic assay for detecting EGFR L858R mutations in CTCs.
• To evaluate the feasibility of using CTCs for non-invasive EGFR mutation profiling in NSCLC patients.

Main Methods:

• Established a flow cytometry method to detect EGFR L858R-bearing CTCs.
• Spiked NCI-H1975 cells into blood from healthy donors for method optimization.
• Applied the method to blood samples from 21 NSCLC patients and 10 healthy donors.

Main Results:

• The assay identified EGFR L858R-bearing CTCs in all seven patients with this mutation.
• The method showed 100% positive and 71% negative agreement compared to PCR.
• Detected EGFR L858R-bearing CTCs in three patients initially classified as EGFR wild-type, with two experiencing partial responses to EGFR-TKIs.

Conclusions:

• A feasible, less invasive proteomic approach for binary EGFR mutation detection in CTCs was developed.
• This method offers a novel means for identifying NSCLC patients eligible for EGFR-TKI therapy.
• CTC analysis holds promise for non-invasive molecular profiling in cancer diagnostics.