Zilbrysq vs. Rystiggo: 5 Differences Between These Targeted Myasthenia Gravis Treatments

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Picture a typical day, whatever that looks like. Maybe it's time in the office, dinner with family, and your favorite show before bed. Whatever the case, as you live your life, your immune system is working hard behind the scenes to fight off unwanted germs, chemicals, and cell changes. You don't even notice. But when it stops functioning smoothly, it demands your attention.

This is the case with myasthenia gravis (MG), an autoimmune condition that causes immune system proteins called antibodies to attack the space between your nerves and muscles. This causes muscle weakness in the eyes, face, and limbs. More severe symptoms can show up in the muscles that you use to swallow and breathe.

In the past, MG treatments were only able to broadly suppress the immune system. But these often take a while to work, cause long-term side effects, and don't work for everyone. Zilbrysq (zilucoplan) and Rystiggo (rozanolixizumab-noli) are two newer MG therapies that are designed to address these issues.

Let's discuss five key differences between these targeted therapies so you can determine the best option for you.

1. Zilbrysq and Rystiggo are both targeted therapies, but they work in different ways

Zilbrysq and Rystiggo both calm the immune system to alleviate MG symptoms. But they do so in different ways. In order to understand how these medications work, it's important to dive deeper into details about the immune system.

The complement system is a collection of proteins in your immune system that promotes inflammation. It "complements" your immune system by helping it fight off foreign substances and germs. But Zilbrysq is a complement inhibitor. It blocks the ability of complement proteins to communicate with each other. This decreases inflammation and prevents the body from attacking itself.

Rystiggo isn't a complement inhibitor. It speeds up the breakdown of antibodies. This includes those that attack our own bodies.

2. Zilbrysq is an injection, while Rystiggo is an infusion

Zilbrysq is an injection you can give to yourself under the skin once daily. It comes in a prefilled syringe, so you don't have to measure out the dose yourself. You can do this in the comfort of your own home.

You'll have to go into your neurologist's office or an infusion center to receive Rystiggo. It's an infusion that is given under your skin once a week for 6 weeks. It takes about 10 to 20 minutes to infuse Rystiggo. And after each infusion, you'll likely be asked to wait around for an additional 15 minutes so your team can monitor you for any reactions. After 6 weeks, your neurologist will decide whether you need additional treatments.

Good to know: In some cases, you may be able to receive Rystiggo at home. A healthcare professional, such as a nurse, may be able to administer it at your residence if doing so is approved by your insurance plan.

3. Zilbrysq and Rystiggo each showed benefits in clinical trials

The majority of people with MG have antibodies in their body that target a protein called the acetylcholine receptor (AChR). This protein is responsible for sending signals from your nerves to your muscles. You're considered "AChR-positive" if these antibodies are found in your blood.

Zilbrysq works best among people with MG who test positive for these antibodies. In one study, people with anti-AChR antibodies who received Zilbrysq daily for 12 weeks saw better improvements in symptoms and quality of life compared to placebo. It helped improve a collection of symptoms, including the ability to eat, talk, swallow, and perform other daily tasks. Symptoms like these can improve as quickly as 1 week after starting the treatment.

Anti-AChR antibodies aren't the only potential culprit. People with MG can also have antibodies in their body that attack a different protein, called muscle-specific kinase (MuSK). This type of MG is more rare and difficult to treat. But Rystiggo is one treatment option to consider for it.

Rystiggo can treat people with MG who have anti-AChR and/or MuSK antibodies. Treatment with Rystiggo also improves MG symptoms, regardless of how long you've had MG, which treatments you've tried in the past, and how severe your condition is. Decreases in antibodies and improvements in symptoms were seen as early as the first week of treatment in clinical studies.

4. They each have their own risks and side effects to keep in mind

Zilbrysq and Rystiggo both lower immune system function. But they each have unique side effects to consider.

Zilbrysq-specific side effects

One of the most common Zilbrysq side effects is injection site reactions - specifically bruising. Rotating the injection site with each dose can improve injection site reactions and decrease bruising. You have the option of injecting Zilbrysq under the skin of the stomach or thighs. You can also ask someone close to you to give you the injection in the back of your arm.

Inflammation of the pancreas can rarely occur. Your neurology team will likely perform a blood draw to assess your pancreatic health before starting Zilbrysq.

Rystiggo-specific side effects

Some of the most common Rystiggo side effects are headache, fever, allergic reactions, and nausea. Some of these may happen during your infusion, and you may receive supportive medications beforehand to prevent them.

Headaches may happen in over 40% of people who receive Rystiggo. You can generally treat these headaches with an over-the-counter pain reliever such as ibuprofen (Advil, Motrin) or acetaminophen (Tylenol). Call your neurology office or go to the ER if you experience a severe headache or vision changes.

Allergic reactions happen in about 10% of people who receive Rystiggo. It can happen during the infusion and up to 2 weeks after. Rash and swelling of the lips and face are the most common symptoms. Contact your neurology team immediately if you develop a new rash, swelling of the face or throat, or trouble breathing.

Shared side effects

Zilbrysq and Rystiggo can both cause infection and diarrhea. Make sure to use good infection prevention practices, such as washing your hands after touching surfaces in public places and avoiding those who are sick. You shouldn't receive either medication if you have an active infection. Ask your prescriber if you should receive any vaccines before starting Zilbrysq or Rystiggo, too.

Diarrhea can be treated with an over-the-counter anti-diarrheal such as loperamide (Imodium A-D). Make sure you also stay well hydrated - persistent diarrhea can lead to dehydration. Reach out to your neurologist if you continue to have uncontrolled diarrhea despite your best efforts at treating it.

5. Zilbrysq has a REMS program

Zilbrysq can increase your risk of developing meningitis. This is a serious and potentially life-threatening infection that causes brain and spinal cord inflammation. Zilbrysq has a boxed warning associated with this risk - the strongest warning given to a medication by the FDA.

What's more, Zilbrysq has an FDA-implented Risk Evaluation and Mitigation Strategy (REMS) program in place. This program is meant to minimize the risk of meningitis infection and ensure Zilbrysq is used safely. Your neurologist and dispensing pharmacy both must be enrolled in the program in order for you to receive Zilbrysq.

You'll also be asked to be vaccinated for meningococcal infections before starting Zilbrysq. If you've already been vaccinated, your neurologist will determine if you need any additional doses of vaccine.

How to choose between Zilbrysq and Rystiggo

If you want the increased convenience of being able to administer your medication at home, Zilbrysq may be a better option. It can cut down on travel time and visits to the clinic. Also, if you experience sudden worsening of MG symptoms, Zilbrysq can be combined with rescue medications such as intravenous immunoglobulin and plasma exchange. You won't have to worry about them interfering with Zilbrysq treatment.

If you have a fear of needles or aren't able to self-administer injections, Rystiggo may be a better option. It's also given less often and doesn't have the same meningitis risk. You may also be able to stop receiving the treatment from time to time - you may get a break after 6 weeks of Rystiggo while your healthcare professional evaluates your response. Lastly, Rystiggo was specifically studied in people with MuSK-positive MG. This may be a better option if you have this type of MG.

Your neurologist will help you decide on the best treatment for you. The decision may also come down to what your insurance will cover.

How to save on Zilbrysq and Rystiggo

Zilbrysq and Rystiggo are only available as brand-name medications. But GoodRx can help you navigate ways to save on your prescription.

• Save with a copay savings card. If you have commercial insurance, you may be eligible to pay as little as $0 for Zilbrysq using a savings card from the manufacturer. You may also be eligible to pay as little as $0 for Rystiggo using a different savings card.

• Save with patient assistance programs. If you're uninsured or underinsured, you may be eligible for Zilbrysq's or Rystiggo's patient assistance programs, which offer the medication at no charge for up to 1 year.

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