Vyvgart: The First FDA-Approved Biologic to Treat Myasthenia Gravis

Historically, myasthenia gravis (MG) — a rare autoimmune condition that interferes with how your nerves and muscles work together — has been difficult to treat. Common MG medications are able to help with symptoms, but some are known to cause unpleasant side effects. Still there is no cure for MG, but in the last few years, much progress has been made in offering new treatment options.

In 2021, the FDA approved a medication called Vyvgart (efgartigimod alfa) to treat MG. It was the first biologic medication available to treat this condition, making it quite different to existing therapy options. More recently, in 2023, another form of Vyvgart, called Vyvgart Hytrulo (efgartigimod alfa / hyaluronidase), was also approved. This version of Vyvgart is injected under the skin.

So what makes Vyvgart an important treatment option for MG? Here, we’ll discuss Vyvgart side effects, how it works, and more.

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What is Vyvgart used for?

Vyvgart is a biologic medication that treats generalized MG in adults who are anti-acetylcholine receptor (AChR) antibody positive.

We’ll talk more about what anti-AChR antibodies are later. For now, just know that biologic medications like Vyvgart often target the immune system. They’re more complex and harder to make compared to other, non-biologic medications.

How does MG affect the body?

MG is a chronic, autoimmune condition where the body mistakenly attacks parts of its own healthy cells. In MG, the immune system makes antibodies (defensive proteins) that disrupt how your nerves and muscles work together. This leads to muscle weakness that tends to get worse after activity and improve with rest.

Muscle weakness from MG can cause problems with everyday activities. Talking, chewing, and swallowing can be more difficult than usual. Other symptoms include double vision, drooping eyelids, and shortness of breath.

What makes Vyvgart different from other MG medications?

Vyvgart is specifically designed to stop antibodies from attacking healthy proteins in the body. It’s the only FDA-approved medication of its kind. While most other medications for MG help with symptoms, they don’t target the source of the problem — stopping the antibodies that cause MG — and Vyvgart does. 

How does Vyvgart work to treat MG?

To understand how Vyvgart works, we need to understand the relationship between our nerves and muscles.

How do nerves and muscles work together?

Our nerves control how our muscles move throughout the body. Nerves release a chemical called acetylcholine. Acetylcholine travels to the muscle cells and binds to an acetylcholine binding site (receptor). This sends a signal to the muscle cells, telling them to contract (move). But with MG, our nerves and muscles don't communicate as expected.

With MG, antibodies called anti-AChR antibodies block acetylcholine receptors so acetylcholine can’t attach. The result is a muscle that can’t contract normally. This causes the main symptom of MG: muscle weakness all over the body.

How does Vyvgart work to treat MG?

Vyvgart treats MG by blocking a protein called the neonatal Fc receptor (FcRn). Normally, FcRn plays a role in keeping antibodies in the body longer. By blocking FcRn, Vyvgart lowers levels of anti-AChR antibodies in the body. 

Vyvgart is only approved for people with generalized MG who are anti-AChR antibody positive (about 85% of people with generalized MG). If you have generalized MG and want to know if you’re anti-AChR antibody positive, talk to your healthcare provider about completing a blood test to find out.

How are Vyvgart and Vyvgart Hytrulo different?

There are two major differences between Vyvgart and Vyvgart Hytrulo:

• They’re administered in different ways. Vyvgart is given as an intravenous (IV) infusion. Vyvgart Hytrulo is given as an injection under the skin (subcutaneously).

• Vyvgart Hytrulo contains an additional ingredient. Both medications treat MG in the same way and are FDA approved for anti-AChR antibody positive MG. But Vyvgart Hytrulo contains an additional ingredient — recombinant human hyaluronidase. The hyaluronidase ingredient improves how well the medication gets absorbed by the body.

How is Vyvgart dosed?

The recommended Vyvgart dose will depend on how much you weigh. It’s given as an IV infusion over the course of one hour. You’ll receive the infusions from a healthcare professional. This might be at an infusion clinic or a healthcare provider’s office.

Vyvgart Hytrulo is dosed differently. The same dose is recommended for everyone, regardless of your weight. It takes around just 30 to 90 seconds to inject. As with Vyvgart, Vyvgart Hytrulo must be administered by a healthcare professional.

A treatment cycle of Vyvgart or Vyvgart Hytrulo spans 4 weeks. This means a total of four infusions per cycle. In the clinical study that earned Vyvgart FDA approval, cycles were spaced at least 50 days apart. The number of Vyvgart cycles you need depends on your symptoms and how well Vyvgart is working for you. Your healthcare provider will help you decide how many cycles you need.

How effective is Vyvgart?

The major clinical study of Vyvgart — the ADAPT trial — found that Vyvgart was more effective than placebo (an infusion with no medication in it) at lessening symptoms of generalized MG in people who are anti-AChR antibody positive. 

The ADAPT trial was a randomized, controlled trial, the gold standard for clinical studies. Researchers looked at Vyvgart’s ability to improve MG symptoms, including ease of talking, chewing, and breathing. The study found that 68% of people treated with Vyvgart had significant improvement in their symptoms versus 30% of people treated with placebo. 

Afterwards, most people entered into an “open-label” study (where they knew they were receiving Vyvgart). This study (the ADAPT+ study) showed that the positive effects of Vyvgart continued over the course of 2 years of treatment. This suggests that Vyvgart may improve symptoms long after you start taking it. 

Additionally, the study leading to Vyvgart Hytrulo’s FDA approval — the ADAPT-SC trial — showed that Vyvgart Hytrulo worked just as well as Vyvgart in people with MG who were anti-AChR antibody positive.

Does Vyvgart have side effects?

Yes, as with all medications, side effects are possible with Vyvgart.

The most common side effects of Vyvgart are:

• Respiratory tract infections, such as the common cold

• Headaches

• Urinary tract infections

• Tingling sensations in your arms or legs

• Muscle aches

• Injection site reactions with Vyvgart Hytrulo, including rash, redness, and itching

In the ADAPT trial, most infections in people taking Vyvgart weren’t severe. But it’s possible to have more serious infections during treatment. This is because Vyvgart can weaken your immune system, and this can raise your risk for infection. If you have an existing infection at the time you’re supposed to receive Vyvgart, let your healthcare provider know. They may delay your dose.

It’s also possible to have an allergic reaction to Vyvgart. In the ADAPT trial, allergic reactions weren’t severe. Symptoms included rash, shortness of breath, and swelling under the skin (angioedema). These reactions occurred within 1 hour to 3 weeks after Vyvgart was given. 

Your healthcare provider will monitor you for symptoms of an allergic reaction during your infusions and afterwards. If you have an allergic reaction during the infusion, your infusion will likely be stopped. If you experience an allergic reaction after going home, call your healthcare provider immediately or get emergency help.

Does Vyvgart interact with other medications?

Vyvgart hasn’t been studied for drug interactions, but it may interact with other medications that bind to the same receptor (FcRn). This may include monoclonal antibodies and immunoglobulin products.

You should also avoid getting a live vaccine while receiving Vyvgart infusions. Live vaccines are made with a live, weakened form of the germ they’re meant to protect against. Vyvgart may interact with these vaccines, making them less effective or making it more likely that you get sick from the vaccine. Examples of live vaccines include the MMR vaccine and the nasal flu vaccine (Flumist).

Vyvgart cost: How to save on Vyvgart

Vyvgart and Vyvgart Hytrulo are only available as brand-name medications. But if you have commercial insurance, you may be able to save with a copay savings card. You may be eligible to pay as little as $0 for Vyvgart using a savings card from the manufacturer.

Why trust our experts?

Written by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

Reviewed by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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