HER2 lung cancer: mutations, protein expression and treatment choices

Identify the HER2 finding on your report

HER2 is also called ERBB2. Sequencing can identify an activating mutation in the gene. Amplification describes increased copies of the gene, while immunohistochemistry measures protein expression. A report can contain one or several of these findings.

Ask whether the treatment recommendation is driven by a mutation, amplification or staining score. A breast cancer explanation of HER2 positivity may not answer the lung cancer question. The test method and exact result should be carried into every discussion about a targeted drug.

Sources and references: [1] [2]

An activating mutation can open a defined treatment route

HER2-mutated NSCLC has become a distinct treatment subgroup. The exact alteration and stage still matter, as do prior chemotherapy and HER2-directed medicines. A molecular result may support a particular kinase inhibitor or antibody-drug conjugate under its applicable indication.

Ask the team to list the realistic options at your present treatment line. If there are several, compare evidence in patients with a similar history, the risk of lung inflammation and the monitoring burden. The most familiar drug name may not be the best match to the current setting.

Sources and references: [2] [3]

What an antibody-drug conjugate does

An antibody-drug conjugate, or ADC, attaches a cell-targeting antibody to a drug payload. Trastuzumab deruxtecan is a HER2-directed ADC with a role in previously treated HER2-mutated NSCLC. It has a different design and prescribing framework from ordinary trastuzumab.

ADCs can cause low blood counts, nausea and other systemic effects. Interstitial lung disease or pneumonitis is a particularly important concern with some HER2-directed ADCs. Before treatment, ask how pre-existing lung problems will be assessed and which new respiratory symptoms should trigger immediate contact.

Sources and references: [2]

Trastuzumab rezetecan in the China setting

Trastuzumab rezetecan, also known as SHR-A1811, is another HER2-directed ADC. Its China lung cancer indication covers adults with unresectable locally advanced or metastatic NSCLC carrying an activating HER2 mutation after at least one systemic treatment. The drug also has other cancer indications, which should be kept separate from lung cancer eligibility.

The HORIZON-Lung phase 2 study evaluated this treatment in previously treated HER2-mutated NSCLC in China and reported antitumor activity. Bring your earlier treatment records so the oncologist can compare your situation with that group. Low blood counts and interstitial lung disease were clinically relevant side effects, so blood-test monitoring and a plan for new breathing symptoms belong in the treatment discussion.

Sources and references: [4] [5]

HER2 kinase inhibitors are another treatment category

The options are no longer limited to ADCs. Zongertinib and sevabertinib have US indications for defined HER2 tyrosine kinase domain activating mutations in advanced nonsquamous NSCLC, with expansions during 2026. Their approved populations and monitoring requirements should be checked individually.

This can be useful when discussing a treatment sequence or an alternative to an ADC. It does not mean every HER2-expressing tumor matches an oral inhibitor. Ask whether your exact mutation is covered and which local options are available in the country where treatment would occur.

Sources and references: [6] [3]

A protein score needs its own evidence

If the report shows HER2 expression without an activating mutation, ask which treatment evidence applies to that result. Some therapies have indications defined by high protein expression in particular settings, while other proposals belong in clinical trials. Amplification may also need a separate review.

A useful consultation should identify the test threshold and prior-treatment requirements instead of relying on the broad phrase HER2 positive. If the result is borderline or the tissue is old, the team can explain whether another sample would materially change the decision.

Sources and references: [1] [2]

Choose the sequence around prior treatment and lung health

If an ADC or kinase inhibitor has already been used, bring the response history and reason it ended. Progression and intolerance lead to different questions. Ask whether a proposed new agent has evidence after the treatment you received and whether a clinical trial would be more relevant.

Report new cough, shortness of breath or fever promptly during therapy. Do not assume these symptoms are simply part of lung cancer. The team may need to distinguish infection, disease progression and treatment-related inflammation before giving another dose.

Sources and references: [2] [5]

Preparing a HER2-focused review in Shanghai

EastMedGo can help organize an inquiry using the full molecular report, HER2 staining if performed, recent scans and previous drug names. The molecular-review information can help you frame the question for a Shanghai team.

State the decision clearly: whether the result supports an ADC, whether a kinase inhibitor is relevant, or what remains after a prior HER2 medicine. We can help clarify appointment requirements and coordination arrangements. The hospital can then address the current local indication and treatment logistics before travel.

Common questions