The videos above were produced in 2021. For the latest treatment options, speak with your doctor.

Support for this educational program provided by Amgen, AstraZeneca, Blueprint Medicines, Bristol Myers Squibb, Genentech, Lilly Oncology, Merck, Novartis and Pfizer.

What is HER2?

Errors in the HER2 gene are one type of lung cancer biomarker. HER2 (also known as ERBB2) is a signaling receptor in the cell. It belongs to a family of signaling receptors that also includes EGFR, so sometimes you may hear the two talked about together. There can be mutations in the HER2 gene or a patient can have too many copies of the HER2 gene (also called an amplification).

Who is most likely to have a HER2 mutation?

HER2 mutations tend to be more common in adenocarcinoma non-small cell lung cancer patients that have little to no smoking history and are female. About 2% of all lung cancer patients have HER2 mutations.  

How do you know if you have a HER2  mutation or amplification?

There are several ways to detect errors in HER2. The best way is through comprehensive next-generation sequencing (NGS). This type of testing places tissue from a patient’s tumor (gathered from a biopsy) in a machine that looks for many possible biomarkers at one time. There may be some situations where a patient can’t undergo the biopsy needed to perform NGS, and so liquid biopsy is recommended. A liquid biopsy can look for certain biomarkers in a patient’s blood. 

HER2 amplifications are tested using immunohistochemistry (IHC), which examines tumor tissue under a microscope. Talk to your doctor to make sure one of these tests was performed.  

Learn more about the different types of biomarker tests here.

What is the course of treatment like for someone with a HER2 error?

Right now, treatment is available for patients who have a type of HER2 mutation called a HER2 exon 20 insertion mutation. Treatment for advanced-stage lung cancer with this mutation is chemotherapy with or without immunotherapy, followed by a targeted therapy (given through IV) called fam-trastuzumab deruxtecan (Enhertu). Some patients may receive a different targeted drug called ado-trastuzumab emtansine (Kadcyla), which is approved for breast cancer but sometimes used in HER2-positive lung cancer.

Treatment for advanced-stage HER2 amplification depends on the amount of HER2 in the tumor. Some patients may receive fam-trastuzumab deruxtecan (Enhertu) after prior treatment with chemotherapy (with or without immunotherapy). 

Many other HER2-targeted medications are being studied in a clinical trials. Ask your doctor if a clinical trial is right for you. 

Work with your doctor to discuss your goals and options each time you have to make a treatment decision. The three big questions to ask are:

  1. What is the goal of this treatment?
  2. What are the potential side effects?
  3. What other options do I have?

Research is happening at a rapid pace and your doctor should be up to date on the recommendations for your specific type of lung cancer. If you don’t feel comfortable with the answers you are receiving, do not hesitate to seek out a second opinion.

Where can I get support?

Page last updated: October 9, 2025

Freedom From Smoking Clinic - Chardon, OH
Chardon, OH | Sep 10, 2025
Fight For Air Climb - Cleveland, OH
Cleveland, OH | Mar 01, 2026