Advancing Treatment Options for Pediatric Myasthenia Gravis: A Q&A With Jonathan Strober, MD

In November during the 2025 American Association of Neuromuscular & Electrodiagnostic Medicine meeting, Jonathan Strober, MD, a pediatric neurologist from the University of California, San Francisco, and Benioff Children's Hospital, presented new data from the ongoing phase 2/3 VIBRANCE-MG trial (NCT05265273). This trial is evaluating pediatric response to nipocalimab for generalized myasthenia gravis (MG) in patients 2 years to younger than 18 years (international arm) and in patients 8 years to younger than 18 years (US arm). At present, nipocalimab is approved for use in patients 12 years or older who are anti–acetylcholine receptor positive or anti–muscle-specific kinase antibody positive.

In this interview, Strober emphasizes the positive safety and efficacy results seen in pediatric patients that are comparable with those seen in adult patients. He also speaks of the difficulties in diagnosing MG in a pediatric population, as well as the need to improve testing, standardize care, and overcome regulatory and insurance barriers to grant necessary treatment access to younger patients.

This transcript was lightly edited for clarity and conciseness.

AJMC: How was the VIBRANCE-MG trial designed to evaluate nipocalimab?

Strober: The VIBRANCE-MG trial is the child and adolescent arm of the study that was done in the adult population on a drug called nipocalimab. Nipocalimab is an antibody that basically prevents the antibodies that you have, the immunoglobulins, from being able to be recycled. It basically drops the amount of immunoglobulins you have in your body. It doesn't drop [the level] completely—so you still have the ability to fight infections, which is how we use the antibodies—but the antibodies are what cause a lot of the problems in myasthenia by attaching themselves to the receptors on the muscle, blocking them from being stimulated or causing them to be broken down. By dropping the antibodies you have in your blood, you can help prevent a lot of the problems that these antibodies cause and therefore improve the symptoms.

AJMC: According to the data you presented at AANEM, what is the overall message regarding nipocalimab’s safety and efficacy?

Strober: The trial that we presented data on looked at kids who were 12 years to just under 18 years. There is an ongoing trial for younger kids, 8 to 12 years in this country and 2 to 12 years internationally, so that we get a better sense of: does this work the same way as it does in adults and is it as beneficial as it was in adults? We're happy to say that, yes, it kind of dropped the antibodies pretty much the same as it did for the adults, and the safety was actually really good. There was a very low risk of problems. Maybe a little bit of infection in the nose and pharynx being the most common, and COVID-19 was actually the other highest amount of adverse effects. But it's hard. I don't really consider that an adverse effect since people get COVID all the time. But we do know that because your antibodies are lower, you definitely are at higher risk of infection. Still, it doesn't really seem to be that significant of a risk, which is great. Patients did really well with it.

Most of the patients continued on through 72 weeks of taking this medication, so past the initial phase of the safety study. A lot of them were able to move from an every-other-week treatment to a once-a-month treatment. Only 1 patient had the flu during it and stopped for a little bit but then was able to go back on. Another patient had some worsening of symptoms, kind of outside the window, which happens in myasthenia—it is an up-and-down type of thing—but the patient was able to get treated for that bit of worsening and stayed on medication. Only 1 person stopped because they felt it wasn't doing anything for them.

AJMC: What are the next steps in your investigation of nipocalimab?

Strober: We still have the trial ongoing, so we're still following patients out longer. Only 3 patients had made it to the 72 weeks at the time of the cutoff when we looked at the data, so it takes a little while to kind of process the data and then be able to present it, since it all has to be scrutinized and checked out to make sure it's all good for us to present. It is ongoing in the world; it's international, and like I said earlier, we're trying to get younger and younger kids into the trial.

It's just really hard for us to get patients into trials like these because [we have less chance of finding the antibodies in] the kids that we want to have in order to enroll them in the study, and a lot of them are not as severe as the adults. They only get problems with the eyes, or they just have mild weakness, and then some of them are really severe and then we can't have them in a clinical trial—so it's kind of a middle ground that we're looking for in patients who have positive antibodies. We are still trying to recruit patients into the study. The first cohort was the 12-to-18 years range, and now the second cohort is a 2-to-12-year-old range.

In the US, it's only limited to 8 to 12 years, but internationally, it's down to 2. That is the ongoing nipocalimab trial. It's kind of an extension of this, it's just the second cohort. We wanted to make sure it was safe in a slightly older population and ones that we have a better ability to test. Once you get down to the younger kids, it's harder to do some of the functional testing that we do for these patients and really know if it's helping, but we are enrolling patients in that cohort.

AJMC: With myasthenia gravis being so rare in pediatric patients, what factors are thought to trigger the disease in younger patients?

Strober: One is that a lot of kids, for some reason, don't make the antibodies like we see in adults. It’s, again, something we know is working on the antibody level, so we want to make sure the patients who are in the trials have the antibodies that we can watch and make sure they're dropping to make sure it’s effective for that. We do know that in some patients who have myasthenia, who we believe have myasthenia but are antibody negative, what we call seronegative, if we repeat their testing over time, eventually they do develop the antibodies. For whatever reason, the antibody levels get delayed in appearing in the blood.

We're also developing better tests to be able to pick up small amounts of antibodies better. We're using better state-of-the-art testing to be able to confirm. We have other ways of confirming myasthenia in patients who are seronegative by doing electrical testing and testing with different medications to see if it’s something that we believe they truly have, even if they don't have the antibodies. But again, for these studies, we need to make sure we're really doing this study in a patient population that's as similar as possible, and so having those antibodies helps us make sure that we're trying to treat the same condition.

AJMC: How do insurance and regulatory decisions influence whether patients can actually receive the most appropriate treatment?

Strober: I don't know exactly what they go through in Europe vs what we go through in this country. I can tell you that if it's not approved by the FDA, it's really hard to get insurance companies to cover it. Often they say it’s experimental if it’s not approved by the FDA, but even once it's approved by the FDA, because the newer drugs tend to be a little bit more expensive than older drugs, and the older drugs [are] more generic [and] cheaper, a lot of insurance companies try to push us to use the older stuff, even though those still haven't been approved for this specific condition. It's just that they're older and we've been using them for longer. It's really important for these regulatory agencies to approve them or provide positive feedback so that these drugs can be used and [we] know they're being used safely, but also that they can get paid for our patients.

AJMC: What are some key unmet needs in the myasthenia gravis treatment landscape?

Strober: I think one is, in pediatrics, again, trying to come up with better tests would be really nice. I think what we're trying to do in our pediatric myasthenia gravis consortium, which has 6 centers currently, is to develop better tools to follow these patients but also develop a standard of care. There really is no standard of care for these patients. We're just so used to using drugs that have only been approved for adults that people just try the different ones on kids and hope that they're safe and hope we have the right dosing, and so kind of getting a better sense of what are people doing out there and what do we actually see in real life, in real time, what is actually working for the patients, so we can put together and say, “Hey, you know what, this is what we recommend as people who take care of these patients and take care of a good number of these patients, this is really the treatment options that you should go [with] and what route you should go in, what's the safest for the patients, what's the most effective for the patients.” That’s really what I want to see; I really want us to get a better understanding of pediatric myasthenia gravis and how we can follow these patients and best take care of them safely.

I think also what I've learned is that the reason that there are so many studies is because now it's become a requirement that in order to get approval for adult drugs, the companies have to have a pediatric arm. That's been a wonderful thing.

Just to be given the opportunity to talk about pediatric myasthenia gravis, that people are actually caring about kids with this condition, has been a huge step forward for those of us in the community who take care of it. I've had so many patients who have been told by providers, “Oh, myasthenia doesn't happen in kids. They can't have myasthenia.” We're kind of used to that in pediatrics for these rarer diseases, so the fact that word's getting out that, yes, kids can get myasthenia gravis and that we can treat them and we can treat them effectively and safely, it's just wonderful to have that opportunity, so I appreciate that, and thank you.