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 like a guided missile, specifically targeting cancer cells that have too much of a protein called HER2, while leaving your healthy cells largely untouched.

If your doctor has recommended trastuzumab, it means your cancer tests positive for HER2 overexpression. This actually gives you access to a highly effective treatment option that has helped many people with similar cancers live longer, healthier lives.

What is Trastuzumab?

Trastuzumab is a type of immunotherapy called a monoclonal antibody. Think of it as a specially designed protein that acts like a smart bomb, seeking out and attaching to HER2 proteins that are overproduced in certain cancer cells.

This medication belongs to a class of drugs called targeted therapies. Unlike traditional chemotherapy that affects all rapidly dividing cells, trastuzumab specifically targets cancer cells with high levels of HER2 protein. This targeted approach often means fewer side effects compared to conventional chemotherapy.

The drug 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. About 20-25% of breast cancers are HER2-positive, meaning they have too much HER2 protein on their surface.

For breast cancer, doctors use trastuzumab in several situations. It can treat early-stage breast cancer after surgery to help prevent the cancer from coming back. It's also used for advanced or metastatic breast cancer that has spread to other parts of the body.

In stomach cancer, trastuzumab helps treat advanced gastric adenocarcinoma when the cancer cells also overexpress HER2. Your doctor will test your cancer tissue to confirm it's HER2-positive before starting this treatment.

How Does Trastuzumab Work?

Trastuzumab works by blocking the HER2 protein on cancer cells, which stops them from growing and dividing. When cancer cells have too much HER2, they grow and spread more aggressively than normal cells.

This medication attaches to the HER2 receptors like a key fitting into a lock. Once attached, it prevents growth signals from reaching the cancer cell. This essentially puts the brakes on cancer cell growth and can cause the cancer cells to die.

Trastuzumab is considered a moderately strong cancer treatment. While it's generally gentler than traditional chemotherapy, it's still a powerful medication that requires careful monitoring by your healthcare team.

How Should I Take Trastuzumab?

Trastuzumab is given as an IV infusion in a medical setting, not as a pill you take at home. Your healthcare team will prepare and administer the medication for you.

Before your infusion, you don't need to fast or avoid eating. In fact, having a light meal beforehand can help you feel more comfortable during the treatment. Drink plenty of water to stay hydrated, and wear comfortable clothes since you'll be sitting for a while.

The first infusion usually takes about 90 minutes, while subsequent treatments typically take 30-60 minutes. Your nurse will monitor you closely during the infusion and for a period afterward to watch for any reactions.

How Long Should I Take Trastuzumab For?

The length of trastuzumab treatment depends on your specific situation and type of cancer. For early-stage breast cancer, treatment typically lasts one year with infusions every three weeks.

For advanced or metastatic cancer, you may continue treatment as long as it's helping control your cancer and you're tolerating it well. Your doctor will regularly assess how well the treatment is working through scans and blood tests.

Never stop taking trastuzumab without discussing it with your oncologist first. Even if you're feeling well, the medication may still be working to keep your cancer under control.

What Are the Side Effects of Trastuzumab?

Most people tolerate trastuzumab well, but like all medications, it can cause side effects. The good news is that serious side effects are relatively uncommon, and your healthcare team knows how to manage them.

Here are the more common side effects you might experience during treatment:

• Fatigue and feeling more tired than usual
• Headaches that are typically mild to moderate
• Nausea, though usually not severe
• Diarrhea or changes in bowel habits
• Muscle aches and joint pain
• Infusion reactions like fever, chills, or skin rash

These common side effects are usually manageable and often improve as your body adjusts to the treatment. Your healthcare team can provide medications and strategies to help minimize these effects.

There are also some less common but more serious side effects that require immediate medical attention:

• Heart problems, including weakened heart muscle
• Severe allergic reactions during infusion
• Lung problems such as difficulty breathing
• Severe infections due to lowered immune function

Your doctor will monitor your heart function regularly with tests like echocardiograms or MUGA scans. If you experience chest pain, shortness of breath, or swelling in your legs, contact your healthcare team immediately.

Who Should Not Take Trastuzumab?

Trastuzumab isn't suitable for everyone, and your doctor will carefully evaluate whether it's right for you. People with certain heart conditions may not be able to take this medication safely.

You should not take trastuzumab if you have a known severe allergic reaction to the medication or any of its ingredients. Your doctor will also be cautious if you have a history of heart problems, including heart failure or significant heart rhythm abnormalities.

Pregnancy is another important consideration. Trastuzumab can harm an unborn baby, so effective birth control is essential during treatment and for several months after. If you're pregnant or planning to become pregnant, discuss this with your doctor immediately.

Trastuzumab Brand Names

Trastuzumab is available under several brand names, with Herceptin being the most well-known original version. This was the first trastuzumab approved by the FDA and has been helping patients for over two decades.

Several biosimilar versions are now available, including Ogivri, Ontruzant, Herzuma, and Trazimera. Biosimilars are highly similar to the original medication and work just as effectively, often at a lower cost.

Your doctor or insurance company may prefer one version over another, but all FDA-approved trastuzumab products are considered equally effective and safe for treatment.

Trastuzumab Alternatives

If trastuzumab isn't suitable for you, other HER2-targeted therapies are available. Pertuzumab is another monoclonal antibody that's often used in combination with trastuzumab for enhanced effectiveness.

T-DM1 (ado-trastuzumab emtansine) is a newer option that combines trastuzumab with a chemotherapy drug. This medication delivers chemotherapy directly to HER2-positive cancer cells while sparing healthy cells.

For some patients, newer options like tucatinib or neratinib might be considered, especially if the cancer has spread to the brain or if other treatments haven't worked well.

Is Trastuzumab Better Than Other HER2 Treatments?

Trastuzumab remains the gold standard for HER2-positive cancer treatment, but newer medications often work best when used together rather than as replacements. Each treatment has its own strengths and is chosen based on your specific situation.

Compared to pertuzumab alone, trastuzumab has a longer track record and more extensive research supporting its use. However, many doctors now use both medications together because they complement each other's actions.

T-DM1 might be preferred in certain situations, particularly when cancer has progressed on other treatments. Your oncologist will consider factors like your overall health, cancer stage, and previous treatments when choosing the best approach for you.