Clonal dynamics of BRAF-driven drug resistance in EGFR-mutant lung cancer

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Epidermal Growth Factor Receptor (EGFR) inhibitors are standard treatments for EGFR-mutant lung cancer.
• BRAF mutations can activate MAPK signaling, potentially limiting EGFR inhibitor efficacy.
• The role of BRAF mutations in the emergence and selection of resistant clones during anti-EGFR therapy is not well understood.

Purpose of the Study:

• To investigate the impact of BRAF mutations on clonal evolution and resistance to EGFR inhibitors in EGFR-mutant lung cancer.
• To evaluate the efficacy of combined EGFR, RAF, and MEK inhibition in preclinical models.

Main Methods:

• Whole-exome sequencing to track subclonal mutations.
• Clonal analyses of individual metastases during therapy.
• Functional analyses of polyclonal cell pools.
• In vivo studies using EGFR-driven xenograft models with BRAF V600E mutations.

Main Results:

• BRAF V600E enrichment and reduced EGFR inhibitor susceptibility were observed in a dose-dependent manner.
• Resistant clones remained stable but became susceptible to combined EGFR, RAF, and MEK inhibition.
• Osimertinib/trametinib combination therapy, not monotherapy, achieved significant tumor shrinkage in xenograft models.

Conclusions:

• BRAF co-mutations influence clonal dynamics and resistance to EGFR inhibitors in lung cancer.
• Combined EGFR, RAF, and MEK inhibition is a promising therapeutic strategy for BRAF V600E-mutated EGFR-driven lung tumors.
• These findings may guide the development of improved treatment strategies for better patient prognosis.