All EGFR mutations are (not) created equal: focus on uncommon EGFR mutations.

Area of Science:

• Oncology
• Genetics
• Molecular Biology

Background:

• Epidermal Growth Factor Receptor (EGFR) mutations are key drivers in non-small cell lung cancer (NSCLC).
• Common EGFR mutations (del19, L858R) respond to tyrosine kinase inhibitors (TKIs).
• Uncommon EGFR mutations occur in approximately 10% of NSCLC patients and often exhibit resistance to standard TKIs.

Purpose of the Study:

• To characterize the clinical features and outcomes of patients with uncommon or compound EGFR mutations in NSCLC.
• To evaluate the efficacy of EGFR tyrosine kinase inhibitors (TKIs) in patients with these rare mutations.

Main Methods:

• Retrospective review of 490 EGFR-mutated NSCLC samples.
• Inclusion of 44 cases with uncommon/compound EGFR mutations for survival analysis.
• Analysis of mutation types, patient demographics, smoking history, and treatment response.

Main Results:

• Sixty (12.2%) patients presented with uncommon/compound EGFR mutations, predominantly non-smokers (86.7%).
• Common uncommon mutations included G719X, L861Q, S768I (31.7%), and exon 20 insertions (28.3%).
• First-line afatinib in 7 patients yielded a median progression-free survival of 8.13 months and an overall response rate of 57.1%.

Conclusions:

• Rare and dual EGFR mutations in NSCLC are heterogeneous, displaying distinct clinical characteristics.
• This study provides insights into the molecular landscape and treatment response in a large Indian cohort.
• Afatinib demonstrates potential efficacy in managing NSCLC patients with uncommon EGFR mutations.