Enhertu is a targeted medication used to treat specific HER2-positive or HER2-low cancers. Dosage is determined by body weight and the specific condition being treated.
The following table shows recommended dosages of Enhertu by condition. Doses are in milligrams (mg) per kilogram (kg) of body weight. One kg is approximately 2.2 pounds (lb).
Your medical team will calculate your specific Enhertu dosage based on your condition and your body weight.
| Condition | Recommended dosage | Frequency |
|---|---|---|
| Breast cancer (HER2-positive, HER2-low, HER2-ultralow) | 5.4 mg/kg | Every 3 weeks |
| Non-small cell lung cancer (HER2-mutant) | 5.4 mg/kg | Every 3 weeks |
| Solid tumors (HER2-positive) | 5.4 mg/kg | Every 3 weeks |
| Stomach cancer (HER2-positive) | 6.4 mg/kg | Every 3 weeks |
When used to treat HER2-positive breast cancer, Enhertu may be administered alone or followed by an injection of another cancer drug called Perjeta (pertuzumab).
Your doctor may adjust or delay your Enhertu dose based on:
- Side effects: Severe lung problems, low white blood cell count, or heart problems may require a dose reduction.
- Treatment response: Whether your cancer is stable or progressing.
- Weight changes: Significant weight loss or gain will trigger a recalculation of your dose.
Enhertu dose reduction
If you experience bothersome Enhertu side effects, your doctor may reduce your Enhertu dosage using the following “step-down” protocol. Once a dose is reduced, it is not typically increased again.
- For breast cancer: 5.4 mg/kg → 4.4 mg/kg → 3.2 mg/kg
- For non-small cell lung cancer (NSCLC): 5.4 mg/kg → 4.4 mg/kg → 3.2 mg/kg
- For stomach (gastric) cancer: 6.4 mg/kg → 5.4 mg/kg → 4.4 mg/kg
Depending on how severe your side effects are, you may need to pause your treatment until your symptoms are relieved. If you have severe side effects, your doctor may permanently stop your Enhertu treatment.
Enhertu is given as an intravenous (IV) infusion by a healthcare professional in a clinical setting.
- First infusion: Typically lasts 90 minutes to monitor for reactions
- Subsequent infusions: If the first dose is well-tolerated, later infusions usually take 30 minutes
- Cycle: Doses are administered once every 21 days (3-week cycle)
Yes, Enhertu is typically used as a long-term treatment. If you and your doctor determine that Enhertu is safe and effective for you, you’ll likely use it long term.
Your dose of Enhertu is based on your weight in kg, so your maximum dose will vary depending on your weight.
If you’re using Enhertu to treat breast cancer, non-small cell lung cancer (NSCLC), or solid tumors, the maximum recommended dose is 5.4 mg/kg of body weight. If you’re using Enhertu to treat stomach cancer or gastroesophageal cancer, the maximum dose is 6.4 mg/kg.
Your medical team will do your Enhertu dose calculation for you.
No, having liver problems typically won’t affect your Enhertu dosage. But your doctor may monitor you more closely during treatment to make sure the drug isn’t causing you harm.
If you have a liver problem and are concerned about receiving Enhertu, talk with your doctor.
If you miss an appointment for your Enhertu infusion, contact your doctor immediately. Do not wait until your next scheduled cycle. Your team will reschedule the dose as soon as possible and reset your 3-week cycle from that new date.
Enhertu has boxed warnings from the Food and Drug Administration (FDA) for the following risks. A boxed warning is the strongest warning the FDA requires. It alerts doctors and patients about drug effects that may be dangerous.
Interstitial lung disease and pneumonitis
Interstitial lung disease and pneumonitis, including fatal cases, have been reported with Enhertu. Call your doctor immediately if you develop signs and symptoms of these serious conditions, including cough, fever, trouble breathing, or other new or worsening respiratory symptoms.
Embryo-fetal toxicity
Enhertu can cause harm to a developing fetus. If you are sexually active and can become pregnant, effective birth control is required during Enhertu treatment.
For more details, discuss these warnings with your doctor.
Note: This summary article is for informational purposes only. For more details, see Enhertu’s prescribing information or talk with your doctor. Also, always follow the specific dosing instructions provided by your oncologist.
Disclaimer: While Healthline strives for factual, comprehensive, and current information, this article is not a substitute for a licensed healthcare professional’s expertise. Always consult a doctor before taking or discontinuing any medication. Drug information is subject to change and may not cover all uses, directions, precautions, warnings, interactions, reactions, or adverse effects. The lack of a warning does not guarantee a drug’s safety, effectiveness, or appropriateness for all patients or specific uses. Learn more about our approach to content integrity.