TORONTO — Novartis' experimental oral multiple sclerosis drug remibrutinib significantly reduced relapses in two large late-stage trials, according to data presented at a medical conference in Toronto on Friday, October 23 — but the benefit fell short of what analysts had hoped for, intensifying a high-stakes race with Roche's rival drug, Reuters reported.
Illustration: A modern medical research laboratory with a glowing molecular structure model representing BTK inhibitor research for multiple sclerosis.
What Happened
Detailed results from the two pivotal Phase III trials of remibrutinib, previously disclosed only in top-line form, were presented at the medical conference in Toronto on Friday. The drug reduced annualized relapse rates by 35.2 percent and 31.2 percent in the two studies, compared with teriflunomide — an older MS treatment sold by Sanofi under the brand name Aubagio — according to Reuters' account of the presentation.
The numbers landed below the bar analysts had set. Before the readout, analysts had expected a relapse reduction in the range of 45 to 60 percent. Instead, the detailed data arrived just days after Roche released pooled Phase III data for its own oral MS drug, fenebrutinib, which reported a 55 percent reduction in annualized relapse rate versus the same comparator, teriflunomide.
Both remibrutinib and fenebrutinib belong to a class of treatments known as BTK inhibitors. The class has previously been linked to liver toxicity, making safety a closely watched concern for investors and regulators alike. On that front, the two drugs appear to differ: while Roche's fenebrutinib showed significantly higher liver enzyme elevations versus the comparator drug, Novartis said there was no liver safety signal in its drug, Reuters reported.
Illustration: An artistic close-up concept of oral medication capsules and a glass of water beside a stethoscope.
Background
Multiple sclerosis is a chronic autoimmune condition in which the immune system attacks the protective myelin sheath around nerve fibers, disrupting communication between the brain and the rest of the body. Relapsing forms of the disease are marked by periodic flare-ups of neurological symptoms. Existing blockbuster therapies include the anti-CD20 class, which targets and destroys the immune cells that drive the disease — Ocrevus from Roche, Kesimpta from Novartis itself, and Briumvi from TG Therapeutics.
BTK inhibitors represent the next generation of oral contenders. Ahead of the Toronto readout, analysts had said that relapse improvements similar to those seen in Roche's fenebrutinib trial would be needed to show that this class of treatments is better than the currently used anti-CD20 therapies.
Heinz Wiendl, co-chair of the Novartis studies, struck a measured tone in an interview, saying of the two BTK drugs: "All in all, they might be quite similar in what they do in terms of reducing relapses and disability."
For Novartis, the stakes extend beyond one disease. The Swiss drugmaker is banking on remibrutinib's success across different therapeutic areas, especially following a string of recent trial setbacks for its heart drug pelacarsen and its muscle weakness therapy del-desiran. Analysts currently estimate remibrutinib could bring in over $4 billion in peak sales, if approved for patients with relapsing forms of MS.
Illustration: An abstract scientific concept of immune cells and nerve fibers with a protective shield effect.
Why It Matters
The readouts frame a direct contest over the future standard of care for relapsing multiple sclerosis. A pill that works as well as infused or injected anti-CD20 antibodies — with a cleaner safety profile — could reshape treatment for millions of patients around the world. Roche currently holds the efficacy edge in the head-to-head narrative, but its liver enzyme signal could complicate the drug's path through regulators and prescribers. Doctors treating a lifelong disease weigh such signals heavily, because patients may stay on a therapy for decades without interruption.
Novartis' cleaner safety profile is its counterweight. Liver toxicity has dogged the BTK inhibitor class, and the absence of a liver safety signal in remibrutinib's data may matter as much to doctors and health agencies as the percentage-point gap in relapse reduction. The market has noticed: investors have been positioning around these readouts for months, and the commercial prize — a multi-billion-dollar oral MS franchise — is large enough that both companies are racing to define the class.
What Happens Next
Regulatory submissions are the next milestone. Analysts will be watching closely for Novartis' filing plans and for how regulators weigh the trade-off between the two drugs' efficacy and liver-safety profiles. Real-world prescriber adoption will hinge on that balance, as will payers' coverage decisions.
Longer-term, Novartis is exploring remibrutinib across additional therapeutic areas, part of its effort to rebuild momentum after the recent setbacks in its heart and muscle programs. Further data — including disability progression measures and longer follow-up — is expected to complete the picture as the company pushes toward approval for patients with relapsing forms of MS.
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FAQ
What is remibrutinib?
Remibrutinib is an experimental oral drug developed by Novartis for multiple sclerosis. It belongs to the BTK inhibitor class of medicines, which are designed to calm the immune system cells believed to drive MS.
How much did remibrutinib reduce relapses in the trials?
According to data presented on October 23, the drug reduced annualized relapse rates by 35.2 percent and 31.2 percent in two Phase III trials, compared with teriflunomide. Analysts had expected a reduction of 45 to 60 percent.
How does it compare with Roche's fenebrutinib?
Roche reported a 55 percent reduction in annualized relapse rate for fenebrutinib in pooled Phase III data versus the same comparator. However, fenebrutinib showed significantly higher liver enzyme elevations, while Novartis said remibrutinib showed no liver safety signal. Novartis study co-chair Heinz Wiendl said the two drugs "might be quite similar" in reducing relapses and disability.
Why is liver safety important for this drug class?
BTK inhibitors have previously been linked to liver toxicity, so regulators and doctors watch liver signals closely. A cleaner liver-safety profile could be a meaningful advantage even when another drug shows stronger efficacy numbers.
When could remibrutinib reach patients?
The drug is still experimental and has not yet been approved. Analysts estimate it could generate over $4 billion in peak annual sales if approved for relapsing forms of multiple sclerosis, pending regulatory submissions and further data.
Sources
- Reuters, "Novartis presents weaker-than-expected relapse data for multiple sclerosis drug remibrutinib," October 23, 2026 — Phase III trial data presented at a medical conference in Toronto; comparisons with Roche's fenebrutinib pooled data; liver safety findings; Heinz Wiendl quote; analyst sales estimates.
- Reuters, "Roche fenebrutinib pooled Phase III data" (reported October 2026) — 55 percent reduction in annualized relapse rate versus teriflunomide.
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