Structural insights into drug development strategy targeting EGFR T790M/C797S

Area of Science:

• Oncology
• Molecular Biology
• Drug Discovery

Background:

• First-generation EGFR inhibitors (gefitinib/erlotinib) are ineffective against T790M mutations in non-small-cell lung cancer (NSCLC).
• Third-generation EGFR inhibitors (WZ4002, CO-1686, AZD9291) target T790M but face resistance from C797S mutations.
• Novel EGFR inhibitors that avoid covalent linkage at Cys797 are needed to overcome T790M and C797S resistance.

Purpose of the Study:

• To present crystal structures of EGFR mutants with reversible inhibitors.
• To identify new strategies for developing next-generation EGFR inhibitors.
• To understand resistance mechanisms and guide future drug design.

Main Methods:

• X-ray crystallography of EGFR activating/drug-resistant mutants.
• Enzyme kinetics assays.
• Site-directed mutagenesis.

Main Results:

• Revealed a previously un-described hydrophobic clamp in the EGFR kinase domain.
• Demonstrated that reversible inhibitors can target EGFR T790M mutants.
• Identified mutations in the hydrophobic clamp that confer resistance by weakening ATP binding or abolishing kinase activity.

Conclusions:

• The hydrophobic clamp is a potential target for developing next-generation EGFR inhibitors.
• Reversible inhibitors offer a promising approach to overcome EGFR T790M and C797S resistance.
• Mutations in the hydrophobic clamp may not readily lead to drug resistance due to compromised kinase activity.