Trastuzumab

Trastuzumab is a prescription medication used to treat breast cancer and stomach cancer.  It may be used alone or in combination with other medications. Trastuzumab belongs to a group of drugs called monoclonal antibodies, which help stop the growth of cancer cells.

This medication comes in an injectable form and is given into the vein (IV) by a healthcare provider once every week or once every 3 weeks.

Common side effects of trastuzumab include fever, nausea, and vomiting.

Breast cancer is a cancer that forms in the cells of the breasts. Some women have (HER2+) breast cancer. (HER2+) stands for Human Epidermal growth factor receptor 2 positive. (HER2) is a special protein found on breast cancer cells that controls cancer growth and spread.

Trastuzumab is approved for treatment of HER2 positive breast cancer, because it is specifically designed to target the HER2 protein. By binding to the HER2 protein, trastuzumab prevents the growth of cancer cells.

HER2 testing is done to see whether treatment with trastuzumab will likely be effective in treating breast cancer. If testing is not done, treatment with this medication may not be an effective treatment.

Trastuzumab is a prescription medication used alone or in combination with other medications to treat certain types of breast cancer that has spread to other parts of the body. Trastuzumab is also used with other medications to treat stomach cancer that has spread to other parts of the body. 

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Trastuzumab may be found in some form under the following brand names:

• Herceptin

Trastuzumab may cause serious side effects (see "Drug Precautions").

The most common side effects associated with trastuzumab in patients with metastatic stomach cancer are:

• Low white blood cell counts
• Diarrhea
• Fatigue
• Low red blood cell counts
• Swelling of the mouth lining
• Weight loss
• Upper respiratory tract infections
• Fever
• Low platelet counts
• Swelling of the mucous membranes
• Swelling of the nose and throat
• Change in taste

The most common side effects associated with trastuzumab in patients with breast cancer are:

• Fever
• Nausea
• Vomiting
• Infusion reactions
• Diarrhea
• Infections
• Increased cough
• Headache
• Fatigue
• Shortness of breath
• Rash
• Low white and red blood cell counts
• Muscle pain

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you are being treated with:

• daunorubicin (Daunoxome, Cerubidine)
• doxorubicin (Doxil)
• epirubicin (Ellence)
• idarubicin (Idamycin)
• paclitaxel (Abraxane, Taxol)

This is not a complete list of trastuzumab drug interactions. Ask your doctor or pharmacist for more information.

Heart Problems

• Trastuzumab treatment can result in heart problems, including those without symptoms (such as reduced heart function) and those with symptoms (such as congestive heart failure). The risk and seriousness of these heart problems were highest in people who received both trastuzumab and a certain type of chemotherapy (anthracycline). One patient died in an adjuvant (early) breast cancer trial of significantly weakened heart muscle.
• Trastuzumab can cause serious heart problems, including:
  • A decline in heart function
  • Irregular heartbeats
  • High blood pressure
  • Serious heart attack
  • Death
• Your doctor will stop trastuzumab therapy if you have weakening of the heart muscle or changes in the heart muscle structure.

Monitoring the Heart

• Your doctor will evaluate your heart function before and during treatment. For adjuvant breast cancer therapy, your doctor will also evaluate heart function after the end of treatment.
• Your doctor may run tests, such as an echocardiogram or a MUGA scan, and will review your health history to see how well the heart muscle is working.
• If you are taking trastuzumab and have stopped treatment temporarily because of significant heart problems, your doctor should monitor your heart health more frequently.

Infusion Reactions

• Some patients have had serious infusion reactions and lung problems; infusion reactions leading to death have been reported
• Symptoms usually happen during or within 24 hours of taking trastuzumab
• Your infusion should be temporarily stopped if you experience shortness of breath or very low blood pressure
• Your doctor should monitor you until these symptoms completely go away
• Your doctor may have you completely stop trastuzumab treatment if you have:
  • A severe allergic reaction
  • Swelling
  • Lung problems
  • Swelling of the lungs
  • Severe shortness of breath
• Infusion reaction symptoms consist of:

Pregnancy

• Trastuzumab can cause harm to the fetus (unborn baby), in some cases death to the fetus, when taken by a pregnant woman
• You should use effective birth control methods while receiving trastuzumab and for at least 6 months after you finish taking trastuzumab
• Nursing mothers taking trastuzumab may want to stop nursing or stop trastuzumab, depending on the importance of the drug to the mother

Lung Problems

Taking trastuzumab Can Result in Serious and Potentially Deadly Lung Problems, Including:

• A severe shortness of breath
• Fluid in or around the lungs
• Weakening of the valve between the heart and the lungs
• Too little oxygen in the body
• Swelling of the lungs
• Scarring of the lungs

Problems like these may occur after an infusion reaction. If you have trouble breathing at rest due to existing lung disease, or large lung tumors appear, you may have more serious lung problems. Your doctor should stop trastuzumab if you experience lung problems.

Additional Important Safety Information associated with trastuzumab

Worsening of Low White Blood Cell Counts Due to Chemotherapy

• Worsening of low white blood cell counts to serious and life-threatening levels and associated fever were higher in patients taking trastuzumab in combination with chemotherapy when compared with those who received chemotherapy alone. The likelihood that a patient will die from infection was similar among patients who received trastuzumab and those who did not

HER2 Testing

• You must have a HER2 test to determine if your cancer is HER2-positive before taking trastuzumab, as benefit has only been shown in patients whose tumors are HER2-positive

• You should contact your doctor immediately for any of the following:
  • New onset or worsening shortness of breath
  • Cough
  • Swelling of the ankles/legs
  • Swelling of the face
  • Palpitations
  • Weight gain of more than 5 pounds in 24 hours
  • Dizziness or loss of consciousness
• If you are pregnant or of childbearing potential, you should know that trastuzumab exposure can result in harm to the fetus (unborn baby)
• You should use effective birth control methods during treatment and for a minimum of six months following trastuzumab
• If you are nursing your baby, you should stop taking trastuzumab or stop nursing

Medicines can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of trastuzumab there are no specific foods that you must exclude from your diet when receiving trastuzumab.

Tell your doctor if you are allergic to any ingredient in trastuzumab, medicines made from Chinese hamster ovary cell protein, benzyl alcohol, or any other medicines.

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements.

Tell your doctor if you have lung disease or heart disease.

Tell your doctor if you are pregnant or breastfeeding.

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

This medication falls into category D.

• Trastuzumab can cause harm to the fetus (unborn baby), in some cases death to the fetus, when taken by a pregnant woman.
• You should use effective birth control methods while receiving trastuzumab and for at least 6 months after you finish taking trastuzumab.

Nursing mothers taking trastuzumab may want to stop nursing or stop trastuzumab, depending on the importance of the drug to the mother. Talk to your doctor if you are breastfeeding or plan to breastfeed. It is not known if trastuzumab is excreted in human breast milk or if it will harm your baby.

Trastuzumab is given intravenously (IV) by a healthcare provider in a medical setting (healthcare provider's office, or hospital). The first dose is usually given over 90 minutes. Subsequent maintenance doses may be given over 30 minutes if the first dose is well-tolerated. Trastuzumab is given once a week or every three weeks, depending on the chosen dosing regimen.

Your doctor will monitor the side effects you experience and your response to therapy, as well as:

• how well your heart, kidneys and liver are functioning
• your complete blood count (CBC)

Take this medication exactly as prescribed by your doctor. Follow the directions on your prescription label carefully. The dose your doctor recommends may be based on the following:

• the condition being treated
• other medical conditions you have
• other medications you are taking
• how you respond to this medication
• your weight
• your height
• your age
• your gender

Adjuvant Treatment of HER2-Overexpressing Breast Cancer

• Option 1: Starting dose of 4 mg/kg over 90 minute IV (into the vein) infusion, then 2 mg/kg over 30 minute IV infusion weekly for 52 weeks.
• Option 2: Starting dose of 8 mg/kg over 90 minutes IV (into the vein) infusion, then 6 mg/kg over 30–90 minutes IV infusion every three weeks for 52 weeks.

Metastatic HER2-Overexpressing Breast Cancer

• Starting dose of 4 mg/kg as a 90 minute IV infusion followed by subsequent weekly doses of 2 mg/kg as 30 minute IV infusions.

Metastatic HER2-overexpressing Gastric Cancer

• Starting dose of 8 mg/kg over 90 minutes IV infusion, followed by 6 mg/kg over 30 to 90 minutes IV infusion every 3 weeks.

If you take too much trastuzumab, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.

If trastuzumab is administered by a healthcare provider in a medical setting, it is unlikely that an overdose will occur. However, if overdose is suspected, seek emergency medical attention.

While you are receiving trastuzumab, your doctor may require you have certain lab tests to check your body's response to trastuzumab. Be certain to keep all appointments with your doctor and the laboratory.

WARNING: CARDIOMYOPATHY, INFUSION REACTIONS, EMBRYO-FETAL TOXICITY, and PULMONARY TOXICITY

Cardiomyopathy

Trastuzumab administration can result in sub‑clinical and clinical cardiac failure. The incidence and severity was highest in patients receiving trastuzumab with anthracycline‑containing chemotherapy regimens.

Evaluate left ventricular function in all patients prior to and during treatment with trastuzumab. Discontinue trastuzumab treatment in patients receiving adjuvant therapy and withhold trastuzumab in patients with metastatic disease for clinically significant decrease in left ventricular function. 

Infusion Reactions; Pulmonary Toxicity

Trastuzumab administration can result in serious and fatal infusion reactions and pulmonary toxicity. Symptoms usually occur during or within 24 hours of trastuzumab administration. Interrupt trastuzumab infusion for dyspnea or clinically significant hypotension. Monitor patients until symptoms completely resolve. Discontinue trastuzumab for anaphylaxis, angioedema, interstitial pneumonitis, or acute respiratory distress syndrome.

Embryo Fetal Toxicity

Exposure to trastuzumab during pregnancy can result in oligohydramnios and oligohydramnios sequence manifesting as pulmonary hypoplasia, skeletal abnormalities, and neonatal death.