Long-Term MINT Data Support Durable Response to Inebilizumab in Myasthenia Gravis

One-year results from the open-label extension of the phase III MINT trial presented at the American Association of Neuromuscular and Electrodiagnostic Medicine annual meeting showed that the benefits of inebilizumab (Uplizna) were sustained in patients with acetylcholine receptor (AChR) or muscle-specific kinase (MuSK) autoantibody-positive generalized myasthenia gravis, with safety and tolerability also maintained.

In this exclusive MedPage Today video, Richard Nowak, MD, of the Yale Myasthenia Gravis Clinic in New Haven, Connecticut, discusses the updated findings, including durable improvements in Myasthenia Gravis Activities of Daily Living (MG-ADL) and Quantitative Myasthenia Gravis (QMG) scores and what the data may mean for longer-term treatment confidence.

Following is a transcript of his remarks:

MINT, or the myasthenia gravis inebilizumab trial, was a phase III placebo-controlled clinical trial that enrolled patients with generalized myasthenia gravis that were either AChR or MuSK autoantibody positive. The randomized controlled period was 52 weeks for the AChR group and 26 weeks for the MuSK group. And there were 190 AChR-antibody patients enrolled and 48 MuSK-antibody patients.

The primary endpoint, which looked at change in MG-ADL score at week 26, was met for the combined study population as well as some of the key secondary outcomes. This led to FDA approval of inebilizumab for the treatment of either AChR or MuSK autoantibody-positive generalized myasthenia gravis in December of 2025.

The study also included an open-label extension period for up to 3 years. In fact, we have patients currently enrolled in the open-label extension. This was optional for patients that completed the randomized controlled period. And what we presented and looked at is an interim analysis of how patients are doing at the 1-year open-label period [OLP] follow-up.

And what we’re observing is that patients continue to demonstrate improvement and benefit based on the patient reported MG-ADL outcome at the 1-year open-label period, as well as with the QMG score. So both the patient-reported and physician-reported outcomes continued to demonstrate a durability of response. Patients that were assigned originally to placebo and then crossed over into active drug also demonstrate consistent clinical improvements in both of those outcome measures, and this was all prespecified.

So in sum, the open-label extension demonstrates that patients continue to have benefit, number one. And number two, it also appears that the longer the patients are post-initiating inebilizumab, there are greater benefits observed over time. So the ADL scores tend to be lower on average. The QMGs tend to be, again, lower on average if you compare to patients over a period of time following initial study treatment.

Additionally, we also followed safety and tolerability during the open-label extension part of the study, which would be expected. And again, safety and tolerability during the OLP was also maintained.

How are these findings important and how do we use these findings? So the study certainly demonstrates that patients that benefit from inebilizumab treatment have a sustained benefit or durability of response over time. And the second is that patients continue to demonstrate that they’re tolerating the medication. So safety and tolerability for an additional 1 year of follow-up was also very good news and positive.

This is something that sometimes comes up over time. Well, if patients get better and it’s safe and tolerable during the randomized control period, how do patients fare over time? Does that response continue, number one? And clearly the response does continue. And actually we see apparently greater responses over time. Again, the study wasn’t really powered to look at some of those nuances, but greater responses are being observed the longer the patient is since initiating the study treatment.

So all of those things combined actually provide additional insight, number one. Number two, greater confidence in the use of inebilizumab for patients with generalized myasthenia gravis with either AChR or MuSK autoantibodies.

So in addition, we will likely have 3-year follow-up data that we will be presenting at future congresses or meetings to get a deeper understanding of how patients do over additional follow-up period. But we thought that it was important to present the 1-year open-label period data at this point in time to provide those additional insights into the role of inebilizumab or anti-CD19 B-cell depletion therapy for patients with a generalized myasthenia gravis. So certainly more to come and we look forward to sharing our data and our work with future meetings.