Biomarkers, Complement Inhibition, and the Future of CIDP Care

Despite the growing number of therapies available for chronic inflammatory demyelinating polyneuropathy (CIDP), substantial unmet needs remain for many patients living with the disorder. CIDP, a rare immune-mediated neuropathy characterized by progressive weakness, sensory dysfunction, and demyelination of peripheral nerves, continues to present significant diagnostic and therapeutic challenges because of its heterogeneous presentation, overlap with disease mimics, and absence of definitive biomarkers.

Over the past several years, increasing research attention has focused on improving early diagnosis, identifying biologic drivers of refractory disease, and developing therapies that may better address long-term disability and axonal injury. At the same time, the field has increasingly looked toward lessons learned from other neuroimmunologic disorders, including multiple sclerosis and myasthenia gravis, where earlier intervention and more targeted therapies have substantially altered long-term outcomes.

At the 2026 American Academy of Neurology (AAN) Annual Meeting, NeurologyLive^® sat down with Karen Lynch, MD, MRCPI, senior global medical director at Sanofi, to discuss the current burden of CIDP, persistent diagnostic barriers, and several ongoing investigational programs evaluating complement inhibition in the disease. Lynch also reflected on the evolving role of biomarkers, longitudinal monitoring tools, and how innovation in CIDP may parallel advancements previously seen across other neuroimmunology conditions.

NeurologyLive: How do you currently frame the burden of CIDP for neurologists, and why does the disease remain underrecognized despite therapeutic advances?

Karen Lynch, MD, MRCPI: I think fundamentally, despite a lot of the therapies that are around, and especially emerging in recent years, there still remains unmet need. About a third of patients don't respond to the first standard of care and may require multiple therapies, and those that do respond, about 70% of them have an inadequate response or a partial response. We still have a ways to go in terms of improving disability for patients.

We've all sort of seen this in practice. Remission is possible, but it's the exception rather than the rule. I think that's where, with Sanofi, we see that there continues to be a lot of work that needs to be done.

People often don't realize the legacy that we have in neuromuscular disease in Sanofi. We started at Genzyme with a deep history there in Pompe disease, Fabry disease, and multiple other neuromuscular disorders. Bringing through our deep immunology expertise at Sanofi, I think we've come up with some great science and research that we're pulling through with some innovative therapies, including our complement inhibitor.

What are some of the major factors contributing to delayed or missed diagnosis in CIDP?

I think even for the best neurologists and neuromuscular experts, it can be hard. CIDP can be overdiagnosed or underdiagnosed, and the challenge is it's not like other neurological diseases where maybe you have an MRI or a biomarker that you can rely on. CIDP is, for the most part, a clinical diagnosis.

We have guidelines that anchor on that clinical diagnosis, and then it requires nerve conduction studies. That in itself can be a hurdle because expertise can vary, and it is just not an easy diagnosis to make.

On top of that, you have many mimics that can resemble CIDP, from diabetic neuropathy, which is very common, to disorders like GBS. So you can see how, based on clinical judgment, examination findings, and nerve conduction studies, which themselves can be difficult to interpret, there are major challenges in anchoring the diagnosis.

The holy grail would be finding a biomarker, or maybe several biomarkers, or a multimodality approach that makes diagnosis easier, because time is nerve when it comes to conditions like this.

How do delays in diagnosis affect long-term outcomes and disability progression in CIDP?

Well, I think delayed diagnosis is a huge issue. If you miss somebody who actually has CIDP, the challenge is that when you have an immune-mediated neuropathy like this, you have a lot of downstream damage occurring on the nerve, on the myelin, and on the axon itself.

Once you cause damage to the axon, then you start to get into an issue of irreversibility. Patients may not fully recover. That's where permanent disability and secondary axonal damage can occur.

That's really the challenge: trying to pick up the diagnosis as early as possible and start patients on appropriate therapy early so you don't reach that axonal damage stage. Once patients have severe axonal damage, it's very hard to come back from that.

This is where innovation is necessary. There are therapies out there, and clinicians are familiar with using them, but they don't work for everyone. With all the science and innovation going on right now, hopefully we're building toward finding signals, creating registries, studying natural history, and understanding this disorder better.

I think it's wonderful to see all the innovation and competition happening because it's really needed for this field. We have seen this before in other neuromuscular and autoimmune disorders. Multiple sclerosis is a great example. CIDP today reminds me of where MS was maybe 10 or 15 years ago, when many things were still unknown and heterogeneous. Then over time, with more research and translational work, we started to identify biomarkers, antibody profiles, and different patient subsets. I think we'll get there eventually in CIDP too.

Can you discuss the ongoing investigational trials evaluating complement inhibition in CIDP?

The first trial is focused on refractory CIDP, and I just want to clarify that we don't necessarily think of these patients as extreme cases. About a third of patients won't respond to first-line therapy, and many require second-line therapies or combinations, so there is still a substantial burden there.

We're studying patients who haven't responded adequately to standard of care and evaluating how they do with our investigational therapy. That trial is called MOBILIZE, and it's ongoing globally right now. We hope to have a readout next year.

The second study is called VITALIZE, and this one is going a step further. We're comparing directly against standard of care, specifically IVIG, which remains the most commonly used therapy in Europe and the United States. It's a double-dummy, double-blind design where patients either receive IVIG or the investigational therapy, and then eventually all continue into an open-label phase.

Part of the reason we designed that study is because in our phase 2 trial we observed that patients transitioning from IVIG to riliprubart showed meaningful improvements. Over half of them improved beyond where they had been previously, and when we presented the longer-term data, nearly 80% remained relapse-free at 76 weeks.

IVIG can carry burden for some patients, whether that's fluctuations in symptoms, treatment access issues, or logistical challenges. So, we felt it was important to study this more directly.

What do we currently understand about refractory disease biology in CIDP?

The difficult answer is that I don't think we fully know, because we're not completely sure what is driving disease in these patients. The treatments currently available may have broader immunomodulatory effects, but CIDP is likely driven by multiple mechanisms.

Antibodies are probably going to be a major piece of it, but they could involve IgG antibodies, IgM antibodies, and different subsets of immune activity. The currently available treatments may only target certain components of those pathways.

Complement inhibition is interesting because complement acts as an effector mechanism causing nerve damage, but it also amplifies innate immune responses and macrophage activity. So, the idea is that shutting down complement may provide a deeper response in patients who aren't adequately responding to existing therapies.

I hope that if successful, it becomes another useful tool in the toolkit to help these patients.

Could complement inhibitors eventually be used alongside standard therapies in CIDP?

It's a really good question, and I think it's definitely something we would want to explore. We already see combination approaches used in disorders like myasthenia gravis to allow more flexibility in care.

Once we have more data, especially from our head-to-head IVIG study, we'll understand more about how these therapies may interact. Patients sometimes still need IVIG boosts or steroid boosts from time to time, so understanding how these therapies may complement each other will be important.

It's definitely an area that deserves more research moving forward.

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