EGFR Mutation in Lung Cancer

This page is for people whose lung cancer report mentions an EGFR mutation. It explains what the result means, which tests find it, the main drugs used, common side effects, and when to call your care team.

EGFR stands for epidermal growth factor receptor. It is a protein that sits on the surface of a cell and tells it when to grow.

Certain changes in the EGFR gene jam that switch in the "on" position. The cell keeps dividing without waiting for a signal. Those changes are called driver mutations, because the tumor depends on them to keep growing.

That dependence is a weakness. Drugs that block EGFR can shut the signal off. NCI states that EGFR variants strongly predict a better response rate and longer progression-free survival in patients who take EGFR inhibitors.

Smoking history changes the odds sharply. NCI cites an analysis of 2,142 lung adenocarcinoma samples from Memorial Sloan Kettering.

• Never-smokers: 52% had an exon 19 deletion or an L858R mutation, or 302 of 580 samples.
• Former smokers: 15%, or 181 of 1,218.
• Current smokers: 6%, or 20 of 344.

The difference between those groups was statistically significant. That is why testing is not skipped in a patient who never smoked.

This is the detail that decides your treatment, and it is easy to miss on a report.

Exon 19 deletions and exon 21 L858R are the two changes NCI calls sensitizing. Tumors carrying them respond to standard EGFR inhibitors. FDA's osimertinib approvals name these two specifically.

Exon 20 insertions behave differently. They sit in the same gene but do not respond the same way. FDA has approved separate drugs for them, described further below.

So "EGFR positive" is not a complete answer. Ask which exon and which specific change.

FDA names a required companion diagnostic with each approval, and the names differ.

The cobas EGFR Mutation Test is the companion diagnostic FDA named for adjuvant osimertinib. Guardant360 CDx is the one named for amivantamab in exon 20 insertions, and it works on blood rather than tissue. FoundationOne CDx also appears on FDA's companion diagnostic list for non-small cell lung cancer, covering EGFR, ALK, and BRAF changes across several drugs.

If your report is blood-based and negative, ask whether tissue testing should follow. A blood test can miss what a tissue sample would show.

FDA approved osimertinib on December 18, 2020 as adjuvant therapy after tumor removal, for non-small cell lung cancer with EGFR exon 19 deletions or exon 21 L858R mutations. Adjuvant means treatment given after surgery to lower the chance of return.

The ADAURA trial supplied the evidence. In stage II to IIIA disease, median disease-free survival was not reached in the osimertinib group. In the placebo group it was 19.6 months, with a 95% confidence interval of 16.6 to 24.5. The hazard ratio was 0.17, with a 95% confidence interval of 0.12 to 0.23.

Dosing is 80 mg by mouth once daily, with or without food. It continues until the cancer returns, until side effects stop it, or for up to 3 years. That is the label's reference amount, printed so you can recognize your own tablets. The prescription your team wrote is the one to follow, and they can lower the dose if side effects build up.

The FDA label lists the approved uses beyond surgery. They are worth knowing, because people often assume one setting is the whole story.

• Stage IIIA, IIIB, or IIIC disease that cannot be removed by surgery and did not worsen during or after platinum-based chemoradiation.
• First treatment for cancer that has spread to other parts of the body.
• Combined with pemetrexed and platinum-based chemotherapy as first treatment for cancer that has spread.
• Cancer that has spread, carries a change called T790M, and grew worse during or after another EGFR tyrosine kinase inhibitor.

That last bullet matters. Cancer can stop responding to a first EGFR drug over time. That is not a sign that testing was wrong, and new testing may look for changes like T790M.

FDA granted accelerated approval to amivantamab on May 21, 2021. The indication was locally advanced or metastatic non-small cell lung cancer with EGFR exon 20 insertion mutations, after the disease progressed on platinum-based chemotherapy.

The CHRYSALIS trial enrolled 81 patients with these mutations. The overall response rate was 40%, with a 95% confidence interval of 29% to 51%. Median duration of response was 11.1 months. A response rate shows how many tumors shrank. It is not the same as living longer.

On March 1, 2024, FDA made that approval a full one. It also approved amivantamab with carboplatin and pemetrexed as a first treatment for exon 20 insertions. In the PAPILLON trial of 308 people, median progression-free survival was 11.4 months with the combination against 6.7 months with chemotherapy alone.

The dose and schedule depend on your body weight and on whether it is given alone or with other drugs, so ask your team for yours.

On July 2, 2025, FDA also granted accelerated approval to sunvozertinib, a pill, for exon 20 insertions that have grown during or after platinum-based chemotherapy.

Osimertinib is not the only choice for exon 19 deletions and L858R. FDA has also approved:

• Amivantamab with lazertinib as a first treatment for locally advanced or metastatic disease with these changes (approved August 19, 2024).
• Amivantamab with carboplatin and pemetrexed when the cancer has grown during or after an EGFR tyrosine kinase inhibitor.
• Datopotamab deruxtecan (accelerated approval, June 23, 2025) for EGFR-mutated disease that has already been treated with an EGFR drug and platinum-based chemotherapy.

Older EGFR pills are approved too. This list is not complete, and approvals keep changing. Ask your team which approved options fit your exact change and your earlier treatment.

EGFR is also on normal skin, nails, and gut lining. That is why the side effect list looks the way it does.

FDA lists these in more than 20% of patients on adjuvant osimertinib: lymphopenia, leukopenia, thrombocytopenia, diarrhea, anemia, rash, muscle and bone pain, nail toxicity, neutropenia, dry skin, stomatitis, fatigue, and cough. Stomatitis means mouth sores. Lymphopenia, leukopenia, neutropenia, and thrombocytopenia are low counts of different blood cells. Anemia means low red blood cells. Nail toxicity often shows as painful, inflamed skin around the nail.

For amivantamab, FDA lists rash, infusion-related reactions, paronychia, muscle and bone pain, shortness of breath, nausea, fatigue, swelling, stomatitis, cough, constipation, and vomiting in at least 20% of patients. Paronychia is that same nail-fold inflammation.

Ask for a skin plan before the rash starts. It is far easier to prevent than to reverse.

• Call 911 if you collapse, have a seizure, or have serious trouble breathing.
• Call right away, at any hour, for a temperature of 100.4°F (38°C) or higher. CDC says to call your doctor immediately for this fever during chemotherapy, and MedlinePlus lists fever as a reason to call immediately on osimertinib. If you cannot reach your team quickly, go to an emergency department and tell them you are being treated for cancer.
• Call right away for a new or worse cough, shortness of breath, or chest pain. Lung inflammation is a known risk with this drug class.
• Call right away for a rash that blisters or peels, or red, painful, or teary eyes. MedlinePlus lists these as reasons to get help immediately.
• Call right away for a fast or pounding heartbeat, or new swelling of the ankles or feet.
• Call the same day for diarrhea that is getting worse. NCI says up to six bowel movements above your normal daily number can usually be managed at home. Seven or more above normal can be life-threatening and may need hospital care. Keep a count.
• Call the same day for nail fold pain with pus or spreading redness.

• Which exact EGFR change was found, and in which exon?
• Which test was used, and was it tissue or blood?
• Is my treatment adjuvant, first-line, or after progression?
• How long is the planned course, and what marks the end?
• What is the plan for rash and nail problems before they start?
• If this drug stops working, what testing happens next?

For related reading, see Biomarker Testing and Precision Medicine, Targeted Therapy vs Chemotherapy, and Pathology Reports.

• FDA Approval Summary: Osimertinib for Adjuvant Treatment of Surgically Resected Non-Small Cell Lung Cancer — Clinical Cancer Research, 2021 (FDA reviewers)
• FDA — FDA Grants Accelerated Approval to Amivantamab-vmjw for Metastatic Non-Small Cell Lung Cancer
• FDA — List of Cleared or Approved Companion Diagnostic Devices
• National Cancer Institute — Non-Small Cell Lung Cancer Treatment (PDQ), Health Professional Version
• National Cancer Institute — Osimertinib Mesylate
• National Cancer Institute — Diarrhea and Cancer Treatment
• CDC — Fever During Chemotherapy
• MedlinePlus — Osimertinib
• DailyMed — TAGRISSO (osimertinib) label
• FDA — FDA approves amivantamab-vmjw for EGFR exon 20 insertion-mutated non-small cell lung cancer indications
• FDA — RYBREVANT (amivantamab-vmjw) prescribing information
• FDA — FDA grants accelerated approval to sunvozertinib for metastatic NSCLC with EGFR exon 20 insertions
• FDA — FDA grants accelerated approval to datopotamab deruxtecan-dlnk for EGFR-mutated NSCLC
• FDA — Drug Trials Snapshots: LAZCLUZE (lazertinib)