Compound EGFR Mutations Are Predominantly P-Loop and Alpha-C Helix Compressing Mutations With Increased...

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Epidermal growth factor receptor (EGFR) kinase domain mutations in non-small cell lung cancer (NSCLC) are classified into four subgroups to predict tyrosine kinase inhibitor (TKI) response.
• These mutations can be single or compound, but the characteristics of compound EGFR mutations, especially PACC/classical co-mutations, are not well understood.

Purpose of the Study:

• To investigate the landscape of single and compound EGFR mutations in NSCLC.
• To assess the drug sensitivity and clinical outcomes associated with PACC mutations, particularly compound PACC mutations.

Main Methods:

• Characterized EGFR mutation types (single vs. compound) in 15,851 NSCLC samples using cell-free DNA (cfDNA).
• Assessed drug sensitivity of mutations using in vitro Ba/F3 models.
• Evaluated clinical outcomes in 1,542 patients from real-world cohorts and literature reviews.

Main Results:

• PACC mutations occurred predominantly as compound mutations (66.2%), unlike classical and exon 20 insertion mutations which were mainly single.
• In vitro models showed compound PACC mutations (including PACC/PACC and PACC/classical) had similar drug sensitivity profiles to single PACC mutations.
• Patients with single or compound PACC mutations demonstrated improved outcomes with second-generation TKIs compared to first- or third-generation TKIs.

Conclusions:

• EGFR PACC mutations frequently present as compound mutations.
• Compound PACC mutations exhibit drug sensitivity patterns comparable to single PACC mutations.
• Second-generation TKIs may offer better clinical outcomes for NSCLC patients with PACC mutations.