Genetic alterations in epidermal growth factor receptor-tyrosine kinase inhibitor-naïve non-small cell lung carcinoma

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) are a standard first-line treatment for advanced non-small cell lung cancer (NSCLC) with activating EGFR mutations.
• Acquired resistance to EGFR-TKIs is common, but natural resistance mechanisms in treatment-naïve patients require further investigation.
• Understanding de novo resistance is crucial for predicting treatment efficacy and developing alternative therapeutic strategies.

Purpose of the Study:

• To determine the frequency of natural resistance mechanisms against EGFR-TKIs in EGFR-mutation-positive, treatment-naïve NSCLC patients.
• To identify specific genetic alterations associated with de novo resistance to EGFR-TKIs.
• To explore the predictive value of these resistance markers for EGFR-TKI therapeutic effects.

Main Methods:

• Analysis of 246 EGFR-TKI-naïve NSCLC patients with known EGFR mutations.
• Detection of EGFR C797S and T790M mutations using peptide nucleic acid-locked nucleic acid PCR clamp.
• Assessment of gene amplification for ERBB2, MET, EGFR, ALK, BRAF, FGFR1, MYC, RET, CCND1, CCND2, CDK4, CDK6, MDM2, and MDM4 via multiplex ligation-dependent probe amplification.

Main Results:

• No concurrent C797S mutations with known EGFR mutations were detected; de novo EGFR C797S was not identified.
• The T790M mutation was present in 4.9% of patients.
• ERBB2 or MET gene amplification occurred in 0.0-0.4% of patients. MDM2 gene amplification was found in some patients and associated with tumor recurrence and shorter progression-free survival (PFS) for first- or second-generation EGFR-TKIs.

Conclusions:

• De novo resistance to EGFR-TKIs in NSCLC is not primarily driven by EGFR C797S mutations.
• While rare, other resistance mechanisms like ERBB2 or MET amplification can be present.
• MDM2 gene amplification is a significant factor associated with poorer outcomes in EGFR-TKI treated NSCLC patients, suggesting its role in de novo resistance and recurrence.