Structural basis of mutant-selectivity and drug-resistance related to CO-1686

Area of Science:

• Molecular Biology
• Structural Biology
• Oncology

Background:

• Non-small-cell lung cancer (NSCLC) with activating epidermal growth factor receptor (EGFR) mutations initially responds to reversible inhibitors like gefitinib and erlotinib.
• Drug resistance, often due to the T790M mutation, limits long-term clinical efficacy.
• Third-generation irreversible inhibitors, such as CO-1686, are designed to overcome resistance by targeting mutant EGFR, including T790M, while sparing wild-type EGFR.

Purpose of the Study:

• To determine the experimentally resolved crystal structure of EGFR T790M in complex with CO-1686.
• To elucidate the structural basis for CO-1686's irreversible inhibition and selectivity for the T790M mutant.
• To understand the structural mechanisms underlying resistance to CO-1686 conferred by EGFR L718Q and L844V mutations.

Main Methods:

• Crystallization of EGFR T790M and L858R mutants.
• Determination of crystal structures of these mutants covalently bound to CO-1686.
• Structural analysis to interpret binding modes and resistance mechanisms.

Main Results:

• The crystal structures of EGFR T790M and L858R mutants covalently bound by CO-1686 were successfully determined.
• Structural data provide insights into the irreversible inhibition mechanism of CO-1686 against EGFR mutants.
• The study explains the selective inhibition of T790M and identifies structural factors contributing to resistance from L718Q and L844V mutations.

Conclusions:

• The determined structures provide a molecular understanding of CO-1686's efficacy and selectivity in EGFR-mutated NSCLC.
• These findings can guide the design of improved irreversible EGFR inhibitors for cancer therapy.
• Understanding resistance mutations is crucial for developing next-generation targeted therapies.