By Theresa Curry
Early next year, biopharmaceutical company Priovant Therapeutics, an affiliate of Roivant Sciences, plans to file for FDA approval of brepocitinib. If approved, the drug could become the first oral, targeted, disease-modifying therapy for dermatomyositis. Following close behind is efgartigamod, another new biologic from argenx.
Speaking at TMA’s MyoCon 2025, Dr. Lisa Christopher-Stine, director of the Johns Hopkins Myositis Center and a member of TMA’s Medical Advisory Board, says this breakthrough comes during an era of significant growth in myositis research. In 2025 alone, she says, more than a dozen phase 2 and 3 studies were underway across the US and Europe.
For years,” she says, “almost every major biologic tested for myositis failed—tocilizumab, abatacept, rituximab, ustekinumab, and belimumab. Intravenous immune globulin (IVIG) therapy was the only bright spot.”
New hope for myositis
Now there’s a new bright spot. Priovant’s phase 3 VALOR trial assigned 241 people with dermatomyositis (DM) treated with standard therapies to receive brepocitinib (either 30 mg or 15 mg once daily) or a placebo for a year, in what the company identifies as the longest and largest successful interventional DM study ever conducted.
TMA members can take some credit for this success. Priovant is a member of TMA’s Corporate Advisory Council (CAC), and our members were eager participants in the trial.
Ben Zimmer, Priovant’s CEO, says DM fits the company’s mission: “We were looking to develop therapies for diseases where there is a heavy patient burden but not much in the way of effective treatments.”
If approved, Christopher-Stine says, “for the first time, we’d have a medicine that improves both muscle and skin and lets patients get off steroids.” And the benefits appeared quickly—by week four—and continued through the year of the trial.
Zimmer says he expects early approval, even with the recent US government shutdown. “Of course,” he says, “you never know, but everything is running well now.”
Data adds up
The main measure used in VALOR was the Total Improvement Score (TIS)—a score that evaluates muscle strength, skin healing, blood tests, and how individuals feel and function. A higher score means greater overall improvement.
At 52 weeks, patients taking 30 mg of brepocitinib averaged an improvement score of 46.5, compared with 31.2 for placebo, a statistically significant difference. Two-thirds achieved a moderate response, and nearly half achieved a major one. The improvement allowed more than 60 percent of those on the 30 mg dose to taper steroids to 2.5 mg or less, with 42 percent stopping steroids entirely.
In its September news release, the company explained how brepocitinib differs from traditional immune suppressants that target the whole immune system. Brepocitinib targets two key cellular enzymes—TYK2 and JAK1—that regulate the signaling of inflammatory proteins. Christopher-Stine describes it as part of a “new wave of targeted therapies that go after the exact pathways we now know are misfiring in myositis.”
Zimmer says the important role those enzymes play in the disease was another factor that steered Priovant towards DM. “It made sense mechanistically.”
Christopher-Stine describes the safety profile of the potential new drug, noting that even though brepocitinib acts powerfully on interferon-driven inflammation, key safety events (blood clots, cardiac events, certain infections, and cancers) did not occur with greater frequency in the brepocitinib 30 mg arm compared to the placebo arm. “This is remarkable for a potent immunomodulator,” she says.
She talks about the ability of patients to inform research, saying that all trials need to measure what those who live with the disease feel and experience, not just lab tests. “Fatigue, pain, and skin symptoms are real and should count,” she says. “Your voices in trial design help make research patient-centered.”
Zimmer thanks the several hundred DM patients around the world who volunteered for the trial. “Every medicine ever approved by the FDA was supported by patient volunteers. No one deserves more appreciation than those who chose to pay it forward.”
More hopeful data
Another CAC member, argenx, is also seeing success with their ALKIVIA trial for efgartigimod. This promising therapy for myositis lowers the antibodies thought to attack muscle tissue. In her presentation, Christopher-Stine says drugs targeting antibody recycling, like efgartigimod, “appear to hold the most promise for sustained remission.”
ALKIVIA, a phase 2/3 study testing the efficacy and safety of efgartigimod, is now fully enrolled with 132 participants. Argenx recently reported results from the study showing improvement in muscle strength and daily function in those with DM, polymyositis, immune mediated necrotizing myopathy (IMNM), and antisynthetase syndrome.
Luc Truyen, chief medical officer for argenx, supported Christopher-Stine’s hope for the drug’s long-term efficacy: “The accumulating body of evidence about the role of IgG autoantibodies reinforces the therapeutic potential of efgartigimod as a new approach for treating several rheumatic diseases, aiming to go beyond symptom management by targeting the underlying disease,” he said.
Efgartigimod, which is already approved as a treatment for generalized myasthenia gravis and chronic inflammatory demyelinating polyneuropathy, prevents antibody recycling allowing the immune system to reset without broad suppression. The success of this trial provides hope for people living with difficult-to-treat forms of myositis, like IMNM.
Referring to all current promising research, Christopher-Stine says: “We’re not declaring victory yet, but for the first time, we can see the path forward.”
Read more:
argenx Advances Clinical Development of Efgartigimod SC in Idiopathic Inflammatory Myopathies
Learn more about clinical trials currently recruiting in myositis.