What is Trastuzumab: Uses, Dosage, Side Effects and More

Trastuzumab is a targeted cancer treatment that helps fight certain types of breast and stomach cancers. This medication works by blocking specific proteins that fuel cancer growth, giving your immune system a better chance to fight the disease.

If you or someone you care about has been prescribed trastuzumab, you likely have many questions about what to expect. This guide will walk you through everything you need to know about this important medication in simple, clear terms.

What is Trastuzumab?

Trastuzumab is a type of targeted therapy called a monoclonal antibody. Think of it as a specially designed key that fits into specific locks on cancer cells.

Unlike traditional chemotherapy that affects all fast-growing cells, trastuzumab specifically targets cancer cells that have too much of a protein called HER2. This protein acts like a growth signal that tells cancer cells to multiply rapidly.

The medication is given through an IV infusion, usually in a hospital or cancer treatment center. Your healthcare team will monitor you closely during each treatment to ensure your safety and comfort.

What is Trastuzumab Used For?

Trastuzumab treats HER2-positive breast cancer and certain stomach cancers. Your doctor will test your cancer cells to confirm they have high levels of HER2 protein before prescribing this medication.

For breast cancer, trastuzumab can be used in several situations. It may be given before surgery to shrink tumors, after surgery to prevent cancer from returning, or when cancer has spread to other parts of your body.

In stomach cancer cases, trastuzumab is typically combined with chemotherapy medications. This combination approach often works better than using chemotherapy alone for HER2-positive stomach cancers.

How Does Trastuzumab Work?

Trastuzumab blocks the HER2 protein on cancer cells, essentially cutting off their growth signals. This makes it harder for cancer cells to multiply and spread throughout your body.

The medication also helps your immune system recognize and attack cancer cells more effectively. By attaching to the HER2 protein, trastuzumab marks cancer cells as targets for your body's natural defense system.

This is considered a strong and effective medication for HER2-positive cancers. Many patients see significant improvement in their condition, though individual responses can vary based on factors like cancer stage and overall health.

How Should I Take Trastuzumab?

Trastuzumab is given as an IV infusion in a medical setting, never at home. Your healthcare team will insert a small tube into a vein in your arm or through a port if you have one.

The first infusion usually takes about 90 minutes, while subsequent treatments typically last 30 minutes. You'll be monitored throughout the process for any reactions or side effects.

You can eat normally before your treatment, and staying hydrated is actually helpful. Drinking plenty of water in the days leading up to your infusion can make the process smoother and may help reduce some side effects.

Your medical team will give you medications before each infusion to help prevent allergic reactions. These pre-medications might include antihistamines or steroids to keep you comfortable.

How Long Should I Take Trastuzumab For?

The length of trastuzumab treatment depends on your specific situation and how well you respond to the medication. Most patients receive treatment for about one year when used after surgery.

If you're receiving trastuzumab for cancer that has spread, treatment may continue as long as it's working and you're tolerating it well. Your doctor will regularly check your progress through scans and blood tests.

Treatment is typically given every three weeks, though some patients may receive it weekly. Your oncologist will create a schedule that works best for your specific type of cancer and overall health.

Never stop taking trastuzumab without talking to your doctor first. Even if you feel better, completing the full course of treatment is important for the best possible outcome.

What Are the Side Effects of Trastuzumab?

Like all cancer treatments, trastuzumab can cause side effects, though many people tolerate it quite well. Most side effects are manageable with proper care and monitoring.

Here are some common side effects you might experience during treatment:

• Flu-like symptoms such as fever, chills, and body aches (especially after the first infusion)
• Fatigue and feeling more tired than usual
• Headaches that may come and go
• Nausea or upset stomach
• Diarrhea or changes in bowel movements
• Muscle or joint pain
• Skin rash or irritation

These symptoms often improve as your body adjusts to the medication. Your healthcare team can provide medications and strategies to help manage these effects.

More serious side effects are less common but require immediate attention. The most important one to watch for is heart problems, as trastuzumab can sometimes affect how well your heart pumps blood.

Contact your doctor right away if you experience any of these more serious symptoms:

• Shortness of breath or difficulty breathing
• Chest pain or unusual chest sensations
• Swelling in your legs, ankles, or feet
• Rapid or irregular heartbeat
• Severe allergic reactions including difficulty breathing, swelling of face or throat
• Signs of infection such as persistent fever or chills

Your medical team will monitor your heart function regularly throughout treatment. This typically involves heart scans every few months to ensure your heart is staying healthy.

Who Should Not Take Trastuzumab?

Trastuzumab isn't suitable for everyone, and your doctor will carefully evaluate whether it's right for you. The most important factor is whether your cancer is HER2-positive, as the medication won't work for HER2-negative cancers.

People with certain heart conditions may not be able to take trastuzumab safely. Your doctor will check your heart function before starting treatment and may recommend alternative treatments if there are concerns.

Here are situations where trastuzumab might not be recommended:

• History of heart failure or serious heart problems
• Previous treatment with certain chemotherapy drugs that can damage the heart
• Severe breathing problems or lung disease
• Severe allergic reactions to trastuzumab or similar medications
• Pregnancy (the medication can harm an unborn baby)

If you're pregnant or planning to become pregnant, it's crucial to discuss this with your doctor. Trastuzumab can cause serious harm to developing babies, so effective birth control is important during treatment.

Your doctor will also consider your overall health, other medications you're taking, and any previous cancer treatments. This comprehensive evaluation helps ensure trastuzumab is the safest and most effective option for your situation.

Trastuzumab Brand Names

Trastuzumab is available under several brand names, with Herceptin being the most well-known original version. This medication has been helping cancer patients for over two decades.

Several biosimilar versions are now available, including Herzuma, Ontruzant, and Trazimera. These biosimilars work the same way as the original medication but may cost less.

Your doctor or pharmacist will let you know which specific brand you're receiving. All approved versions of trastuzumab go through rigorous testing to ensure they're safe and effective.

Trastuzumab Alternatives

If trastuzumab isn't suitable for you, several other treatment options may be available. Your oncologist will consider factors like your cancer type, stage, and overall health when recommending alternatives.

For HER2-positive breast cancer, other targeted therapies include pertuzumab, which is often used alongside trastuzumab, and T-DM1, which combines trastuzumab with chemotherapy in one medication.

Newer options like tucatinib and neratinib may be considered for certain situations, particularly when cancer has spread to the brain or when other treatments haven't worked as well as hoped.

For some patients, traditional chemotherapy or hormone therapy might be recommended instead of or in addition to targeted treatments. Your medical team will help you understand all your options and their potential benefits and risks.

Is Trastuzumab Better Than Other HER2 Treatments?

Trastuzumab is considered the gold standard for treating HER2-positive cancers, but "better" depends on your specific situation. For many patients, it's the most effective first-line treatment available.

Compared to chemotherapy alone, trastuzumab often provides better results with fewer severe side effects. It specifically targets cancer cells rather than affecting all fast-growing cells in your body.

Some newer medications like T-DM1 or combinations with pertuzumab may be more effective in certain situations. However, trastuzumab remains the foundation of treatment for most HER2-positive cancers.

Your oncologist will consider your individual case, including cancer stage, previous treatments, and overall health, to determine the best treatment approach for you.