Zanidatamab-hrii (Ziihera®)

Monoclonal antibodies are created in a lab to attach to the targets found on specific types of cancer cells. The antibody “calls” the immune system to attack the cell it is attached to, causing your immune system to kill the cancer cell. Zanidatamab-hrii is a bispecific HER2-directed monoclonal antibody. HER2 is a protein found on the surface of some cancer cells and this medication binds to two extracellular sites on HER2. It helps stop tumor growth.

How to Take Zanidatamab-hrii

This medication is given as an intravenous infusion (directly into the vein). Your dose depends on the size of your body and your provider will tell you how often you will receive it. How long the infusion takes will depend on how many doses you have received and how you tolerate the medication. About 30 to 60 minutes before your infusion, you will be given medications (pre-medications) to help prevent an infusion reaction. You will be given acetaminophen, an antihistamine, and a corticosteroid. It is important to tell your provider if you are having any new symptoms or side effects. 

Possible Side Effects of Zanidatamab-hrii

There are a number of things you can do to manage the side effects of zanidatamab-hrii. Talk to your care team about these recommendations. They can help you decide what will work best for you. These are some of the most common or important side effects:

Infusion-Related Side Effects

The infusion can cause a reaction that may lead to chills, fever, shortness of breath or trouble breathing, flushing, nausea and vomiting, rash, dizziness, feeling lightheaded, or chest discomfort. Tell your provider right away if you are having any new symptoms during your infusion. Your infusion may be paused or your dose may be decreased depending on how severe your reaction is.

Diarrhea

Your oncology care team can recommend medications to relieve diarrhea. Also, try eating low-fiber, bland foods, such as white rice and boiled or baked chicken. Avoid raw fruits, vegetables, whole-grain breads, cereals, and seeds. Soluble fiber is found in some foods and absorbs fluid, which can help relieve diarrhea. Foods high in soluble fiber include applesauce, bananas (ripe), canned fruit, orange sections, boiled potatoes, white rice, products made with white flour, oatmeal, cream of rice, cream of wheat, and farina. 

Liver Toxicity

This medication can cause liver toxicity, which your oncology care team may monitor for using blood tests called liver function tests. Notify your healthcare provider if you notice yellowing of the skin or eyes, your urine appears dark or brown, or you have pain in your abdomen, as these can be signs of liver toxicity.

Electrolyte Abnormalities

This medication can affect the normal levels of electrolytes (potassium, sodium, etc.) in your body. Your levels will be monitored using blood tests. If your levels become too low, your care team may prescribe specific electrolytes to be given by IV or taken by mouth. Do not take any supplements without first consulting with your care team.

Fatigue

Fatigue is very common during cancer treatment and is an overwhelming feeling of exhaustion that is not usually relieved by rest. While on cancer treatment, and for a period after, you may need to adjust your schedule to manage fatigue. Plan times to rest during the day and conserve energy for more important activities. Exercise can help combat fatigue; a simple daily walk with a friend can help. Talk to your healthcare team for helpful tips on dealing with this side effect. 

Important but Less Common Side Effects

• Heart Problems: This medication can affect how well your heart pumps blood, called left ventricular dysfunction. Your heart function will be checked before and during treatment with this medication. You should contact your provider right away if you have new or worsening shortness of breath, feeling more tired than normal, your feet or ankles are swollen, you lose consciousness, your heart feels like it is beating fast or skipping a beat, sudden weight gain, or feeling dizzy or lightheaded.

Reproductive Concerns

Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant or father a child while on this medication. Effective birth control is necessary during treatment and for at least 4 months after treatment. Even if your menstrual cycle stops or you believe you are not producing sperm, you could still be fertile and conceive. You should not breastfeed while receiving this medication.