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Dianthus Therapeutics has launched a global, late-stage clinical trial to evaluate the safety and effectiveness of its myasthenia gravis therapy, a self-administered injection, versus a placebo in people with generalized myasthenia gravis. The Phase 3 study, dubbed EMERGE, is expected to enroll an estimated 195 adults with gMG and self-reactive antibodies targeting the acetylcholine receptor protein, the most common type of MG-causing antibodies.
Building on Phase 2 Claseprubart Myasthenia Gravis Results
In MAGIC, an earlier Phase 2 trial that was also placebo-controlled, myasthenia gravis treatment was found to be safe and effective in easing symptoms in people with gMG. EMERGE is designed to confirm those benefits and provide robust results that, if positive, may support an application for the treatment’s approval. Top-line results are anticipated in the second half of 2028, according to the company.
Leadership Enthusiasm for the New Trial
“Given the impressive Phase 2 MG results, the medical team has been eagerly anticipating the initiation of this important study and the opportunity to implement important Phase 2 learnings,” said Simrat Randhawa, MD, Dianthus’s executive vice president and head of research and development. “Our internal enthusiasm has been matched by site and principal investigator interest globally so far.” Dianthus called it a “highly potent” therapy with “best-in-disease, pipeline-in-a-product potential” for treating gMG.
Understanding the Disease Behind Claseprubart Myasthenia Gravis Research
An autoimmune neuromuscular disorder, gMG is driven by self-reactive antibodies that mistakenly target proteins, most commonly AChRs, needed for nerve-muscle communication. This leads to muscle weakness across several parts of the body, as well as fatigue and other symptoms. The binding of anti-AChR antibodies to their target promotes activation of the classical pathway of the complement cascade, a part of the immune system, contributing to MG-related damage.
How Claseprubart Targets the Complement Pathway
This therapy, formerly known as DNTH103, is an antibody-based treatment that specifically blocks the active form of the complement protein C1s, thereby reducing activation of the classical complement pathway. This is expected to ease complement-mediated damage and disease symptoms, positioning myasthenia gravis treatment as a targeted approach rather than broad immunosuppression.
Regulatory Status and Dosing Design
The therapy received orphan drug designation in the U.S. for the treatment of myasthenia gravis, which is expected to speed its clinical development. Self-administered via a subcutaneous injection, claseprubart was designed to stay in the body for longer periods, allowing less frequent dosing. In clinical trials, it is being tested as subcutaneous injections every two or four weeks, following an initial intravenous loading dose.
What the Earlier MAGIC Trial Found
The previous MAGIC trial tested two claseprubart doses, 300 mg or 600 mg, against a placebo in 65 adults with gMG and anti-AChR antibodies. Three-month data demonstrated that both doses were generally well tolerated and significantly reduced disease severity relative to the placebo. Still, the low dose, but not the high dose, was significantly superior to the placebo across all five key efficacy measures, including the MG Activities of Daily Living scale and the Quantitative MG scale.
Dose Selection for the EMERGE Claseprubart Myasthenia Gravis Trial
Participants who completed the three-month placebo-controlled portion of MAGIC could enter the trial’s open-label extension, in which all received treatment for up to one year. Early pharmacological data from this extension also supported the selection of the lower 300 mg dose for the Phase 3 trial now underway.
How EMERGE Is Structured
In the newly launched EMERGE study, participants are being randomly assigned to receive either claseprubart or a placebo for about four months, following an initial loading dose and then 300 mg doses administered every two or four weeks. Dianthus has stated the trial will be multicenter and global but has not yet announced study locations or provided enrollment information.
Trial Goals for the Claseprubart Myasthenia Gravis Study
The study’s main goal is to assess whether the treatment is superior to the placebo at reducing scores on the MG-ADL scale, indicating less severe disease. Secondary goals include changes in muscle weakness, assessed with the QMG scale, and disease severity, evaluated with the MG Composite Scale. The trial will also examine changes in participants’ quality of life using the MG Quality of Life 15-item Revised questionnaire.
Measuring Minimal Symptom Expression
Researchers will also assess the proportion of participants reaching minimal symptom expression, defined as an MG-ADL score of zero or one, indicating no symptoms to minimal ones, without the need for rescue therapy. After completing the placebo-controlled portion, participants may enter an extension period during which all will receive treatment for up to two years, or 104 weeks.
