Hydration effects on the efficacy of the Epidermal growth factor receptor kinase inhibitor afatinib

Area of Science:

• Oncology
• Molecular Biology
• Computational Chemistry

Background:

• Small molecule tyrosine kinase inhibitors target EGFR mutations in non-small cell lung cancer (NSCLC).
• Covalent inhibitors like afatinib were developed to overcome resistance to earlier non-covalent inhibitors.
• Afatinib showed differential efficacy in clinical trials (LUX-3, LUX-6) for EGFR 19del vs. EGFR L858R mutations.

Purpose of the Study:

• To investigate the molecular basis for afatinib's differential efficacy in NSCLC patients with EGFR 19del versus EGFR L858R mutations.
• To elucidate the role of structural constraints and binding pocket flexibility in afatinib's varying affinities.

Main Methods:

• Molecular modeling and simulations were employed to analyze the EGFR binding pocket structure.
• Analysis of hydrogen and halogen bonding interactions between afatinib and EGFR mutants.
• Single Nucleotide Polymorphism (SNP) analysis of residues near buried water molecules in the EGFR binding pocket.

Main Results:

• EGFR 19del mutations exhibit reduced binding pocket flexibility due to structural constraints.
• These constraints promote strong hydrogen and halogen bonds between afatinib and EGFR 19del.
• Buried water molecules modulate these interactions, leading to differential binding affinities for afatinib.
• SNP analysis suggests potential for further patient stratification based on surrounding residue variations.

Conclusions:

• Structural differences in EGFR 19del mutations underlie afatinib's enhanced efficacy compared to EGFR L858R.
• Afatinib's strong binding to EGFR 19del is mediated by specific hydrogen and halogen bonds influenced by pocket constraints.
• Investigating SNPs in residues near buried water could enable more precise patient stratification for afatinib therapy.