Rare neuro disorder offers new area for competition, analysts say: #AAN24

An acute competition is emerging among drug developers looking at a rare neurological disorder known as chronic inflammatory demyelinating polyneuropathy, or CIDP, and Wall Street analysts are taking note.

At the American Academy of Neurology’s annual meeting this week, argenx and Sanofi both released trial updates for their CIDP programs. And though argenx has at least a three-year lead with its drug Vyvgart already approved in another indication, analysts expect Sanofi and others — particularly Dianthus Therapeutics and Immunovant — to prove worthy competitors.

The market opportunity is significant, despite CIDP’s low prevalence in the US of less than one in 100,000 people. Argenx’s injectable version of Vyvgart, called Vyvgart Hytrulo, could reach up to $1.5 billion in global peak sales by 2030 for CIDP alone, TD Cowen analyst Yaron Werber wrote, using the current $225,000 price tag in his calculations.

CIDP is a progressive neurological and autoimmune disease of the peripheral nervous system. Over time, patients experience worsening symptoms of fatigue, muscle weakness and a loss of feeling in their arms and legs that can put them in wheelchairs. The only treatment approved for CIDP is Takeda’s HyQvia — OK’ed as a maintenance therapy in January — and the current standard of care is intravenous immunoglobulin, or IVIg.

Karen Massey

Argenx is testing Vyvgart Hytrulo in CIDP, and at AAN the company fleshed out previously reported data from last July. Researchers said subgroup analyses indicated that clinical benefits were observed across all patient subtypes enrolled in the trial and regardless of whether patients received prior treatment.

Karen Massey, argenx’s COO, told Endpoints News the company’s experience getting Vyvgart cleared for use in myasthenia gravis — where it was approved by the FDA as an IV infusion in late 2021 and as an injectable last year — gives it a leg up in CIDP. Argenx has already collected real-world data and can help lessen the patients’ treatment burden, she said.

“We don’t want patients to be spending hours and hours and hours in an infusion chair, getting their treatment for their CIDP,” Massey said. “We want them to be able to be out living their lives.”

Summer FDA decision

Earlier this year, argenx used a priority review voucher to speed up the agency’s assessment of Vyvgart Hytrulo in CIDP. The FDA is expected to make a decision by June 21.

Sanofi’s drug, meanwhile, is a complement C1s inhibitor called riliprubart, which researchers are testing in an open-label Phase 2 trial in patients who previously have and have not been treated with standard-of-care IVIg, as well as those who received IVIg but whose disease progressed.

The trial design differs from argenx’s, making direct comparisons difficult, Stifel analyst Alex Thompson wrote. TD Cowen’s Werber added that argenx pooled treatment-naïve and treatment-experienced patients, while Sanofi also doesn’t identify responders before assessing whether or not a patient relapsed.

Sanofi reported data last year in both of the previously treated groups, but at AAN showed that nine of 12 treatment-naïve patients improved and two others remained stable. Werber wrote that even though Sanofi’s pivotal trials won’t be looking at this population, the data bode well for riliprubart’s prospects.

Replacing a first-line standard of care may also prove too challenging, Werber added. Sanofi is conducting two Phase 3 studies for riliprubart, one in patients who progressed on IVIg treatment or corticosteroids, and another in those who have responded to IVIg. Sanofi has said if the trials read out positively, it expects to file for approval in 2026.

Analysts closely watched the AAN data to determine potential read-throughs to the Dianthus and Immunovant programs. The Dianthus program, also a selective inhibitor of C1s called DNTH103, will launch a CIDP trial in the second half of this year and offers the possibility of less frequent dosing than Sanofi, Jefferies analyst Maury Raycroft said.

Immunovant is developing a monoclonal antibody targeting FcRn for CIDP and Graves’ disease, called batoclimab. Phase 2 data for CIDP are expected in either the second or third quarter this year, while a Phase 2 study in Graves’ disease read out positively late last year. The CIDP trial will be important for benchmark purposes and to see if deeper IgG reductions with FcRn-targeting drugs lead to higher patient responses than Vyvgart, Raycroft wrote.

Editor’s note: A previous version of this story incorrectly said there were no approved CIDP drugs. This story has been corrected to note that Takeda’s HyQvia was approved as a CIDP maintenance therapy.