By Richard J. Nowak, MD, with Rachel Reiff Ellis
Richard J. Nowak, MD, is director of the Myasthenia Gravis Clinic, director of Clinical & Translational Neuromuscular Research (CTNR), and associate professor of neurology at Yale School of Medicine.
The insights shared here represent his knowledge as a medical professional.
Myasthenia gravis (MG) is an autoimmune condition where your body’s defense system makes a mistake and starts to attack the surface of your muscles — specifically the receptors or receivers on your muscle’s surface. When that happens, it affects your muscle’s ability to contract, which causes fatigable muscle weakness.
The proteins that carry out this attack are called autoantibodies. Antibodies are protective proteins your immune system makes in response to harmful substances. Autoantibodies attack your body’s own substances as if they’re foreign and harmful.
Nipocalimab lowers the levels of autoantibodies that cause muscle weakness in people with autoimmune MG. It’s in a class of targeted medications called FcRn inhibitors or FcRn antagonists. FcRn is involved in the recycling of immunoglobulin G (IgG) antibodies. By blocking FcRn, nipocalimab reduces your levels of circulating IgG antibodies, including those that cause autoimmune diseases.
One of nipocalimab’s important features is that it was designed and studied as a chronic maintenance therapy, so people taking it could have an improvement in their disease and maintain that improvement over time.
Who Is This Treatment For?
Nipocalimab is for people with what we call “antibody-positive” MG. MG has different subtypes, and we define them by the autoantibodies we find during diagnosis.
Acetylcholine receptor (AChR) antibodies are the most common autoantibody of MG, and account for up to 80% of people with the disease. A less common autoantibody subtype is muscle-specific tyrosine kinase (MuSK) antibodies, which accounts for 5% to 10% of MG cases.
The way we find out if you have these autoantibodies depends on how your MG presents and where you are in your diagnostic journey. A very common test we do is a blood test to look for the presence of these autoantibodies, specifically AChR antibodies and MuSK antibodies.
What’s Different About This Drug?
There are a number of targeted treatments for MG that have been FDA approved over the last five to seven years. Nipocalimab isn’t different from these drugs in terms of drug class, but the hope is that it will provide much more consistent control of MG symptoms and disease over time than previous options.
So is this a breakthrough treatment? Is this a first in class or a new class of medications? No. But I think it offers people options, especially if someone has tried a prior FCRN antagonist and they're having fluctuating symptoms.
How Effective Is It?
Nipocalimab does not cure MG, but it helps to maintain disease control. The goal of treatment is to lower the disease-causing antibodies in your body. And we hope that translates to improved strength, improved function, and an improvement in overall quality of life. What we can say from the clinical trials is this medication demonstrated clinical benefit within weeks to a couple of months of starting treatment. And so we would expect the same in the outpatient setting now that it's available for prescription.
How Do You Take It?
We give nipocalimab as an IV infusion, typically in an outpatient infusion center. But depending on insurance authorization, some people can get it at home with a home nurse who can give the infusion.
It's not unusual for us to start an infusion like this at an outpatient infusion center so that we can monitor people in a controlled environment. But if it's a treatment that is continued over time and insurance allows us, we do then like to switch it to a home infusion.
We're still learning about how we can best apply medications like nipocalimab and FcRn inhibitors in general. For example, how long should you take it? Right now there isn’t one answer for every person on the drug. It was studied and tested as a chronic treatment. So the thought process is that it would maintain disease control over time.
But for some people, I would say that it is a medication that should be continued for the long term. In other people, it's a medication that should be used only short term. It really depends on the person and how we're using nipocalimab in their treatment regimen. And there are some cases where the medication isn’t really beneficial, and we discontinue it.
What Are the Side Effects?
Infusion-related reactions can occur with any intravenous infusion. They're not common, and they haven’t been reported to be severe, based on clinical trial data we have in hand.
So it’s not a significant concern, but it's something we do let patients know when they receive an infusion therapy. That's also why a nurse gives the IV and it’s not a self-administered drug. We keep an eye on the person taking it to watch for anything concerning.
Who Shouldn’t Take This Drug?
Everyone is different, so there are no absolutes when it comes to who should or shouldn't take nipocalimab. One risk factor that comes up is that many of the medications we have to treat MG are, in fact, immunosuppressive therapies. So when you take them, you raise your risk for infection and infectious complications.
With the FcRn antagonist drugs, the most common complication we see is a urinary tract infection. So if you’re someone who has monthly urinary tract infections, this might not be the best medication for you.
Whether nipocalimab is right for you depends on you and your other health history. It’s a decision you need to make at an individual level with your doctor.
Will Insurance Cover It?
We have to certainly get insurance authorization prior to starting treatment. Depending on your insurance policy and plan, typically you have to go through a step system where we can demonstrate to your insurance company you’ve tried and failed, or you can’t take other standard medications before they’ll cover nipocalimab.
Will that change in time? I hope so. Because this medication is something we should be considering using earlier in people with moderate to severe disease. Many of the other older medications can take months, or even up to a year to achieve clinical benefit.
And some first-line therapies like prednisone or corticosteroids have considerable side effects, especially when used at moderate to high doses. So when your disease burden is high, it’d be great if we could start this medication sooner rather than later.
