Defining the sensitivity landscape of EGFR variants to tyrosine kinase inhibitors

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Tyrosine kinase inhibitors (TKIs) are standard for EGFR-mutated NSCLC.
• Rare EGFR mutations often lack defined treatment options.
• Understanding variant sensitivity to TKIs is crucial for personalized therapy.

Purpose of the Study:

• To systematically assess the sensitivity of a wide range of EGFR variants, including rare mutations, to five common TKIs.
• To create a comprehensive reference for EGFR variant sensitivity to TKIs.
• To explore the potential of saturation mutagenesis and cytotoxicity assays for drug screening.

Main Methods:

• Constructed EGFR variant libraries (substitution-deletion and exon 20 insertion) using saturation mutagenesis.
• Assessed variant sensitivity to afatinib, erlotinib, gefitinib, icotinib, and osimertinib.
• Utilized massively parallel cytotoxicity assays in an EGFR-depleted cell line to determine variant enrichment.

Main Results:

• Evaluated 3914 substitution-deletion and 70,475 insertion variants in EGFR exons 18-21.
• Identified 221 substitution-deletion variants sensitive to EGFR-TKIs.
• Found high enrichment of exon 20 insertion variants (positions 770-774) across all tested TKIs, with frequent glycine or serine insertions.

Conclusions:

• This study provides a comprehensive resource on the sensitivity of diverse EGFR variants to five major TKIs.
• The findings aid in understanding treatment responses for NSCLC patients with rare EGFR mutations.
• The methodology is adaptable for evaluating other gene-drug interactions in targeted therapies.