A method of high-throughput functional evaluation of EGFR gene variants of unknown significance in cancer

Area of Science:

• Oncology
• Genetics
• Pharmacology

Background:

• Large-scale cancer genome projects identify numerous variants of unknown significance (VUS) in oncogenes.
• The functional relevance and clinical impact of these VUS remain largely uninvestigated.
• Investigating VUS is crucial for understanding cancer progression and drug resistance.

Purpose of the Study:

• To develop and apply a high-throughput method for evaluating the transforming potential and drug sensitivity of oncogene VUS.
• To assess 101 nonsynonymous epidermal growth factor receptor (EGFR) mutants using the developed method.
• To identify novel EGFR mutations conferring resistance or sensitivity to tyrosine kinase inhibitors (TKIs) and other targeted therapies.

Main Methods:

• Development of the mixed-all-nominated-mutants-in-one (MANO) method for high-throughput functional assessment of VUS.
• Application of the MANO method to 101 nonsynonymous EGFR mutants.
• Evaluation of transforming potential and sensitivity to EGFR tyrosine kinase inhibitors (TKIs) like gefitinib and erlotinib, as well as cetuximab.

Main Results:

• Identification of multiple EGFR mutations conferring resistance to gefitinib and erlotinib, including exon 19 missense mutations and specific point mutations (L833V, A839T, V851I, A871T, G873E).
• Discovery that compound mutations in the cis allele of L858R-positive tumors decrease gefitinib sensitivity.
• Demonstration that some EGFR mutants highly resistant to TKIs exhibit sensitivity to cetuximab.

Conclusions:

• The MANO method provides a high-throughput platform for functional assessment of oncogene VUS.
• Uncommon EGFR mutations have clinical relevance and their combined effects should be evaluated.
• These findings support the customization of cancer therapy based on individual patient mutation profiles and drug sensitivity.