EGFR C797S
A change that appears in some patients after third-generation EGFR inhibitor therapy.
Parent marker: EGFR
Not a diagnosis and not final medical advice. Must be reviewed by a doctor.
Clinical meaning
C797S changes the binding site of the drug so that ongoing therapy may lose effectiveness. The pattern of its appearance with the T790M influences the following discussion.
How this finding appears in a report
Checked by re-sequencing of tissue or blood after progression.
When therapy stops working
Subsequent options are generally addressed through clinical trials targeting these combinations or mechanisms of resistance.
What needs verification
- Does C797S co-occur with T790M on the same allele.
- Availability of clinical trials that specifically screen for these changes.
- Methods and laboratories that produce results.
Marker context: EGFR
A common EGFR mutation (exon 19 deletion, L858R) alters the way systemic therapy is selected in non-small-cell lung cancer. Other groups of mutations, including exon 20 insertions, are generally considered distinct and are often directed to other pathways, including clinical trials.
A negative result does not always mean absent
Summary
- Gen
- EGFR
- Variant
- EGFR C797S
- Alteration type
- Mutation
- Discussed in
- Lung Cancer
- Updated
- 2026-09-10
Other names in reports
C797S
Treatment categories
Related guides
Sources
- NCI Dictionary of Cancer Terms(lembaga)
- ClinicalTrials.gov(registry)
Clinical trials
Studies mentioning marker EGFR
Filtered from public study descriptions. Access status and site readiness remain unverified.
NCT03191149Phase 2Targeted therapy
Testing Osimertinib as a Treatment for Lung Cancers With an EGFR Exon 20 Change
Lung Cancer | biomarker: EGFR | Targeted therapy
United States347 registry sites
Why this appears: Appears because it is recorded for Lung Cancer, it mentions marker EGFR, the treatment category is Targeted therapy.
What to verify: Acceptance of patients from outside the local country has not been verified.
- Registry
- Recruiting in registry
- Site
- Not verified
- International access
- Unknown
- Patient match
- Not assessed
Last checked 16 Oktober 2026Source ClinicalTrials.govNCT03191149Not verified
NCT07874490Phase 2Targeted therapy
Osimertinib and Cyclosporine A to Enhance Antitumor Efficacy in NSCLC
Lung Cancer | biomarker: EGFR | Targeted therapy
United States1 registry sites
Why this appears: Appears because it is recorded for Lung Cancer, it mentions marker EGFR, the treatment category is Targeted therapy.
What to verify: Acceptance of patients from outside the local country has not been verified.
- Registry
- Recruiting in registry
- Site
- Not verified
- International access
- Unknown
- Patient match
- Not assessed
Last checked 16 Oktober 2026Source ClinicalTrials.govNCT07874490Not verified
NCT04181060Phase 3Targeted therapy
Osimertinib With or Without Bevacizumab as Initial Treatment for Patients With EGFR-Mutant Lung Cancer
Lung Cancer | biomarker: EGFR | Targeted therapy
United States603 registry sites
Why this appears: Appears because it is recorded for Lung Cancer, it mentions marker EGFR, the treatment category is Targeted therapy.
What to verify: Acceptance of patients from outside the local country has not been verified.
- Registry
- Recruiting in registry
- Site
- Not verified
- International access
- Unknown
- Patient match
- Not assessed
Last checked 16 Oktober 2026Source ClinicalTrials.govNCT04181060Not verified
NCT07185997Phase 3Targeted therapy
Study to Evaluate Efficacy and Safety of Firmonertinib Compared With Investigator's Choice of EGFR Inhibitor as First-Line Treatment in Participants Who Have Locally Advanced or Metastatic NSCLC With EGFR P-Loop and Alpha C-Helix Compressing (PACC) Uncommon Mutations
Lung Cancer | biomarker: EGFR | Targeted therapy
United States, Australia, Canada +14139 registry sites
Why this appears: Appears because it is recorded for Lung Cancer, it mentions marker EGFR, the treatment category is Targeted therapy.
What to verify: Acceptance of patients from outside the local country has not been verified.
- Registry
- Recruiting in registry
- Site
- Not verified
- International access
- Unknown
- Patient match
- Not assessed
Last checked 16 Oktober 2026Source ClinicalTrials.govNCT07185997Not verified
Next steps
These suggestions come from links between entries in TanyaKanker's database, not from a medical judgement. Each suggestion includes why it appears.
Next to learn
- EGFR
Biomarker
Reason: Related through a biomarker
- Lung Cancer
Cancer type
Reason: Related to this page
- Targeted therapy
Treatment category
Reason: Related to this page
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Recently updated
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Date: Data revision 2026-09-10
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- Pancreatic Cancer
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Date: Data revision 2026-09-10
- Testing Osimertinib as a Treatment for Lung Cancers With an EGFR Exon 20 Change
NCT03191149 - Phase 2
Date: Registry update in the last 30 days (2026-10-15)
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