Myasthenia gravis is a life-long (chronic) autoimmune condition, which means that the body’s immune system attacks its own healthy cells. Most people with generalized myasthenia gravis (gMG) have antibodies in their system that attack receptors in the neuromuscular junction, which is where the nerve and muscle cells communicate. This blocks signals between the cells and leads to muscle weakness.
Rystiggo is part of a new group of medicines, called FcRn receptor inhibitors, that are approved to target specific parts of your immune system to reduce these harmful antibodies.
How Your Medicine Works
There is no cure for gMG. It causes muscle weakness that can affect various parts of the body. The more you use the muscles, the weaker they become. Common symptoms include the following and can be different from person to person.
- Drooping of one or both eyelids
- Changes in facial expressions due to weakness in your face, jaw, or mouth
- Weakness in your arms, legs, and hands
- Difficulty swallowing
- Trouble speaking
In gMG, two of the harmful antibodies are called anti-acetylcholine receptor (AChR) or anti-muscle-specific kinase (MuSK) receptor antibodies. These antibodies block receptors on muscle cells, preventing them from receiving signals from nerve cells. As a result, the immune system mistakenly attacks the body’s own muscles.
Rystiggo is a new treatment designed to reduce the harmful antibodies causing the symptoms of gMG. Rystiggo targets a protein called the neonatal Fc receptor (FcRn). By binding to FcRn, Rystiggo causes the body to remove the anti-AChR and anti-MuSK antibodies from the bloodstream. With fewer of these antibodies in the blood, there is less blockage of the nerve-to-muscle communication. This can lead to improved muscle strength and fewer MG symptoms for many people.
Can Anyone With Myasthenia Gravis Use Rystiggo?
Rystiggo is approved for use in people with gMG who have certain types of antibodies in their blood, called anti-AChR or anti-MuSK antibodies. Although most (80%-90%) people with MG have one of these antibodies, not everyone does, so it is important to confirm that one of these antibodies is present. Rystiggo may not help people who do not have these antibodies.
How Will I Receive This Medicine?
Rystiggo is commonly given by a health care provider as an infusion under the surface of your skin. The needle is put into your subcutaneous tissue, which is the deeper layer of your skin. It is usually given in the lower part of your belly area, below your belly button (navel).
The dose of Rystiggo you get may be based on your body weight. The infusion will last about 15 minutes, but the exact time may vary. Your health care provider will monitor you for signs of an allergic reaction (hypersensitivity) for up to 15 minutes after the infusion.
Commonly, the infusion is given once a week for six weeks. This is considered a treatment “cycle.” You may have a treatment break between the cycles. Follow the instructions given to you by your health care provider on how often you should receive Rystiggo. Your health care provider will determine how long you should receive Rystiggo in the treatment cycles.
How Was It Studied?
One study was done to look at the safety and efficacy of Rystiggo for gMG. Everyone in the study had MG with anti-AChR or anti-MuSK antibodies, and most people (90%) had anti-AChR antibodies. The average age was 52 years, and the average duration of disease was six years. About two-thirds of the people in the study were female (61%) and White (68%). About 11% were Asian, 3% were Black, and 1% were Native Hawaiian or other Pacific Islander. Most people had mild (39%) or moderate (57%) disease based on the Myasthenia Gravis Foundation of America disease class, with only 4% of the people with a severe disease.
Here is some important information about the treatments that people were using when the study started. These medicines were allowed to continue during the study.
- Most people (86%) were using an anticholinesterase medicine.
- About two-thirds (65%) were taking an oral corticosteroid every day.
- About half (52%) were taking an immunosuppressive medicine.
Two different doses of Rystiggo were compared with a placebo, and no one knew which dose or if they were receiving the medicine or a placebo. Each person received an infusion once a week for six weeks. At the end of the six weeks, everyone was followed for another eight weeks for changes in symptoms and side effects.
The study measured the efficacy of Rystiggo by rating each person’s symptoms using the following scales. A higher score in each scale means that symptoms are more severe.
- The Myasthenia Gravis Activities of Daily Living (MG-ADL) scale, which asks the person to rate how much their symptoms affect different activities in the day, like talking, chewing, swallowing, breathing, seeing clearly, and brushing their teeth and hair. The score ranges from 0 to 24.
- The Quantitative MG (QMG) score, which asks a health care provider to measure muscle strength in different parts of the body. The score ranges from 0 to 39.
- The Myasthenia Gravis Composite (MGC) scale, which combines ratings from the patient and the health care provider for eye function, muscle strength, neck movement, chewing, swallowing, and breathing. The score ranges from 0 to 50.
- The Myasthenia Gravis Symptoms Patient-Reported Outcomes (PRO) scale, which allows a person to rate five core symptoms of MG: overall muscle weakness, neck muscles, eye muscles, overall fatigue, and breathing muscles. The score ranges from 0 to 100.
What Benefits Were Seen in the Studies?
People who received Rystiggo at either dose saw improvements in MG-ADL starting after week one, with maximum improvements at week six. Also, people who received Rystiggo saw improvements in QMG, MGC, and PRO scales. This means that symptoms rated by the people in the study and the health care providers improved more with Rystiggo than a placebo. Overall, people receiving Rystiggo felt that their muscles were stronger, and they were more able to move compared to the people who received a placebo.
Your results may differ from what was seen in clinical studies. You and your health care provider should determine if the benefits outweigh any potential risks.
Signs That the Medicine Is Working
Rystiggo works to improve your muscle strength. You may start to see improvement in your muscles a few weeks after starting Rystiggo infusions.
Do not stop using this or any other medicines for MG without talking with your health care provider first, even if your symptoms have gotten better. Your symptoms may get worse again if you stop or change any of your medicines.
It is important to track your progress and review with your health care provider. Contact your health care provider if you don’t see improvements or your symptoms are getting worse.
Are There Any Reasons Why Rystiggo Should Not Be Used?
Rystiggo should not be started if you have an active infection. Tell your health care provider if you have any of the following symptoms of an infection. They may wait to start your infusion or delay a treatment cycle until the infection is resolved.
- Fever, sweats, chills, or muscle aches
- Coughing or coughing up blood
- Burning, stinging, or pain when you pee
- A runny nose, excess mucus, nasal congestion, or sore throat
- Shortness of breath or wheezing
- Tiredness
- Diarrhea or stomach pain
- Weight loss
How Can I Prevent and Manage Side Effects?
The most common side effects of Rystiggo are headache, fever, an infection in the nose or throat, nausea, diarrhea, severe allergic reactions, and reactions where the needle went in for the infusion.
Headaches are commonly mild to moderate. Talk to your health care provider if you have regular headaches or a headache that is more severe. They may recommend over-the-counter (OTC) medicines to help manage headaches during treatment.
Nausea and diarrhea were common in the first few weeks. Tell your health care provider if you have either of these symptoms. To limit nausea or diarrhea, you can try simple steps such as eating bland foods like rice, bananas, and toast; drinking plenty of water; and lowering the amount of caffeine you are drinking. Call your health care provider if your symptoms are not improving or are getting worse. Your health care provider may prescribe prescription medicines to treat this or may ask you to keep OTC medicines on hand.
Call your health care provider if you are having common cold symptoms or symptoms of other infections. Your health care provider will determine how best to treat the symptoms.
Rystiggo can cause a reaction where the needle goes in, which may involve redness, itching, and swelling. One way to reduce these reactions is to inject the drug into a different part of the body each time, which is called “rotating” the injection site. Tell your health care provider if you have any signs of a reaction where you receive Rystiggo.
These are not all of the possible side effects. Talk with your health care provider if you are having symptoms that bother you. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.
What Types of Interactions Can Happen?
Talk with your health care provider about any vaccines that you may need. You should not receive certain vaccines right before or while using Rystiggo. Tell your health care provider about any vaccines you have recently received or have scheduled.
Rystiggo works by blocking the FcRn receptor. It may lower the effects of other medicines that bind to the FcRn receptor. Tell your health care provider if you are using the following medicines.
- Immunoglobulin products, like intravenous immunoglobulin (IVIg)
- Monoclonal antibodies
- Medicines that use antibody derivatives containing the human Fc domain
This is not a complete list of medicines that may interact with Rystiggo. Tell your pharmacist or health care provider about all the prescription or OTC medicines, vitamins/minerals, herbal products, or other supplements you take or have recently taken. This will help them find out if there are any interactions, or if you need a dosage adjustment.
Getting Your Medicine
Most people will receive Rystiggo at an infusion center. Based on certain requirements, some people may be able to use Rystiggo at home with the help of a nurse. Talk with your health care provider about what option is right for you. The drugmaker has a program to help support the process for you and your health care provider. You can find out more at www.rystiggo.com or by calling 844-669-2731.
Insurance approval. Your insurance may require approval for Rystiggo, also called a prior authorization. The insurance company reviews the prescription from your health care provider to make sure it is covered and determines the process that needs to be followed.
Finding a Rystiggo infusion center. Rystiggo infusions are given at certain hospitals and infusion centers in the United States. Talk to your health care provider about an infusion center near you or find out more information at www.rystiggo.com/infusion-finder.
Financial assistance. There is a financial assistance program from the drugmaker. Whether you are eligible depends on whether you have prescription insurance and what type of insurance you have.
