Related Experiment Video
Updated: May 4, 2026
Deciphering the Structural Effects of Activating EGFR Somatic Mutations with Molecular Dynamics Simulation
Published on: May 20, 2020
Structural, biochemical, and clinical characterization of epidermal growth factor receptor (EGFR) exon 20 insertion
Hiroyuki Yasuda1, Eunyoung Park, Cai-Hong Yun
1Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
Abstract:
Epidermal growth factor receptor (EGFR) gene mutations (G719X, exon 19 deletions/insertions, L858R, and L861Q) predict favorable responses to EGFR tyrosine kinase inhibitors (TKIs) in advanced non-small cell lung cancer (NSCLC). However, EGFR exon 20 insertion mutations (~10% of all EGFR mutations) are generally associated with insensitivity to available TKIs (gefitinib, erlotinib, and afatinib). The basis of this primary resistance is poorly understood. We studied a broad subset of exon 20 insertion mutations, comparing in vitro TKI sensitivity with responses to gefitinib and erlotinib in NSCLC patients, and found that most are resistant to EGFR TKIs. The crystal structure of a representative TKI-insensitive mutant (D770_N771insNPG) reveals an unaltered adenosine triphosphate-binding pocket, and the inserted residues form a wedge at the end of the C helix that promotes the active kinase conformation. Unlike EGFR-L858R, D770_N771insNPG activates EGFR without increasing its affinity for EGFR TKIs. Unexpectedly, we find that EGFR-A763_Y764insFQEA is highly sensitive to EGFR TKIs in vitro, and patients whose NSCLCs harbor this mutation respond to erlotinib. Analysis of the A763_Y764insFQEA mutant indicates that the inserted residues shift the register of the C helix in the N-terminal direction, altering the structure in the region that is also affected by the TKI-sensitive EGFR-L858R. Our studies reveal intricate differences between EGFR mutations, their biology, and their response to EGFR TKIs.
Insights
Most EGFR exon 20 insertion mutations in non-small cell lung cancer (NSCLC) resist tyrosine kinase inhibitors (TKIs). However, the EGFR-A763_Y764insFQEA mutation shows sensitivity, offering a potential treatment avenue.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Epidermal growth factor receptor (EGFR) mutations drive non-small cell lung cancer (NSCLC).
- Specific EGFR mutations (G719X, exon 19 deletions/insertions, L858R, L861Q) predict response to tyrosine kinase inhibitors (TKIs).
- EGFR exon 20 insertion mutations (~10% of EGFR mutations) are linked to primary resistance to existing TKIs like gefitinib, erlotinib, and afatinib, with the underlying mechanisms poorly understood.
Purpose of the Study:
- To investigate the in vitro sensitivity of various EGFR exon 20 insertion mutations to EGFR TKIs.
- To correlate in vitro findings with clinical responses in NSCLC patients.
- To elucidate the structural basis for TKI sensitivity or resistance in EGFR exon 20 insertion mutants.
Main Methods:
- In vitro kinase assays to assess TKI sensitivity of EGFR mutants.
- Analysis of clinical data from NSCLC patients treated with gefitinib or erlotinib.
- Crystal structure determination of representative EGFR exon 20 insertion mutants (e.g., D770_N771insNPG).
Main Results:
- Most studied EGFR exon 20 insertion mutations demonstrated resistance to gefitinib and erlotinib in vitro and in patients.
- The crystal structure of D770_N771insNPG revealed an unaltered ATP-binding pocket but a wedge-like insertion promoting an active kinase conformation, independent of TKI affinity.
- Unexpectedly, EGFR-A763_Y764insFQEA exhibited high in vitro sensitivity to TKIs, and patients with this mutation responded to erlotinib.
- Structural analysis of A763_Y764insFQEA indicated a shift in the C helix register, altering the TKI-binding region.
Conclusions:
- EGFR exon 20 insertion mutations exhibit diverse biological behaviors and differential responses to EGFR TKIs.
- The structural basis for resistance in most exon 20 insertion mutants involves promoting an active kinase conformation without altering TKI binding affinity.
- The EGFR-A763_Y764insFQEA mutation represents a distinct subset of exon 20 insertions that remain sensitive to certain TKIs, offering a therapeutic target.
More Related Videos
09:38Establishing Dual Resistance to EGFR-TKI and MET-TKI in Lung Adenocarcinoma Cells In Vitro with a 2-step Dose-escalation Procedure
Published on: August 11, 2017
11:15Next Generation Sequencing for the Detection of Actionable Mutations in Solid and Liquid Tumors
Published on: September 20, 2016
