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From the Community

June 18, 2025

Bruce Bebo

People in doctor's coats examine MRIs while looking at an iPad. — Image: iStock

Throughout my career I have seen many MS research developments, including the development and refinement of many disease modifying therapies, breakthroughs in myelin repair, new insights into what is driving progressive MS, the establishment of the Pathways to Cures Roadmap and, most recently, updates to the MS diagnostic criteria that will help us diagnose MS earlier and more accurately.Now, we are revisiting the course descriptors of MS — In other words, the terms we use to describe the “types” of MS.You are likely familiar with the existing course descriptors — clinically isolated syndrome (CIS), relapsing-remitting MS (RRMS), secondary progressive MS (SPMS), and primary progressive MS (PPMS) — which were first introduced in 1996, revised in 2013, and clarified in 2020. The International Advisory Committee on Clinical Trials in Multiple Sclerosis, which is co-sponsored by the National MS Society and the European Commission for Treatment and Research in MS (ECTRIMS), established these course descriptors.Last month, this same committee met to discuss revising the course descriptors entirely.

It’s Time for a Change

Why change something that is so familiar to people affected by MS? Because we have learned so much about MS in the last decade that we’re at a major turning point. We are evolving from only understanding how MS presents and appears clinically (as symptoms) to understanding some of the underlying biology that's driving MS.Right now, we can measure MS clinically. You go to your neurologist, and they can measure things like your walking speed and the severity of your symptoms. But none of that addresses the underlying causes of MS in your body. We have MRIs, which are very helpful, but imperfect.In the next few years, I expect we will have additional, valuable tools — such as biomarkers — available to us. We are continuing to invest in technology that can measure what’s happening inside the body (biological markers).As we’ve learned more about the biology of MS, it has become clear that the current descriptors don’t tell the full story of a person’s MS journey. The current descriptors try to put MS into neat categories that many people don't fit into.I think we are all aware that everybody's journey with MS is different, and that MS can present in a lot of different ways. The descriptors we have now are helpful, but they aren’t ideal for informing how we treat MS.There’s a bit of a balance to strike because, while we understand a lot more about the underlying biology of MS than we did when the last version of the disease descriptors was published, we still may not be quite close enough to completely describe MS in biological terms. We still have some gaps in our understanding of what drives different forms of MS, especially the progressive aspects of MS. Measuring progression is a big area we need to get better at.But the hope is that a framework can be developed now that can evolve as we identify some of the pieces that we’re still missing. That’s where we landed at last month’s meeting: The community, which included many top MS researchers, feels like we’re ready to create this new framework, even if all the details aren’t quite there yet.

Why This Matters

What's Next

There is a feeling that we need to work with urgency because the current descriptors aren’t working well for us. But we also need to be cautious because there are a lot of implications for this change.Changing how we describe MS will impact people with MS and their family members, healthcare providers, regulators, drug development companies, insurance companies — the list goes on. Some implications we can anticipate, and others we cannot. That means this change has to be made thoughtfully, considering all of the downstream consequences.There will need to be a lot of preparation, so this isn’t happening tomorrow. We look forward to sharing more as we continue our progress.

Bruce Bebo, PhD, is Executive Vice President, Research at the National MS Society and was previously a research immunologist focusing on the influence of sex hormones on MS. He is a driven and passionate Society volunteer, successful fundraiser and advocate, fueled in part by the fact that his mother had MS.

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