NEW YORK, NY and WALTHAM, Mass. — Dianthus Therapeutics, Inc. (Nasdaq: DNTH), a clinical-stage biotechnology company dedicated to developing next-generation therapies to transform the treatment of severe autoimmune diseases, today announced an early GO decision based on an interim responder analysis in the Phase 3 CAPTIVATE trial of claseprubart in Chronic Inflammatory Demyelinating Polyneuropathy (CIDP).
“We are excited to announce an early GO decision based on results from less than 40 planned participants completing Part A of the CAPTIVATE Phase 3 trial. These interim responder analysis results, in addition to the robust Phase 2 data from our MaGic trial in generalized Myasthenia Gravis, bolster our confidence in the best-in-class target profile for claseprubart and its potential to become a best-in-disease, first-line biologic of choice across a range of large and growing neuromuscular indications,” said Marino Garcia, Chief Executive Officer of Dianthus. “Classical pathway inhibition could replace the standard of care in the multi-billion-dollar CIDP market with the potential for improved efficacy, differentiated safety, and lower patient burden. We expect our planned study design changes to streamline the CAPTIVATE trial and support even faster execution.”
Interim Responder Analysis Results Summary
- The target for the Part A interim responder analysis was a response rate of 50% or greater (i.e., ≥20 confirmed responders out of first 40 participants to complete Part A) based on precedent set with aC1s inhibition.
- This GO decision was reached early, after 20 confirmed responders were achieved with less than 40 planned participants completing Part A of the trial.
- There have been no related serious infections, no clinical symptoms of autoimmune activation, no related serious adverse events or discontinuations.
- The GO decision was confirmed by an independent DSMB review.
Next Steps: Planned CAPTIVATE Trial Design Updates
Dianthus anticipates the following:
- Maintain the claseprubart 300mg/2mL S.C. Q2W dose in Part A;
- Engage with regulators to remove the claseprubart 600mg/4mL S.C. Q2W arm from Part B;
- Enroll up to 256 patients (previously up to 480) in Part A to randomize 128 patients in Part B (previously 192); and
- Provide CAPTIVATE Part B top-line guidance by the end of 2026.
“As a neurologist who specialized in and treated many patients with neuromuscular diseases including CIDP, it is encouraging to see consistency across multiple clinically meaningful measures including INCAT, MRC-SS, Grip Strength, and IRODS in Part A of the CAPTIVATE study,” said James K. Sheffield, MD, Vice President and Head of CIDP Development of Dianthus. “These initial findings motivate the CIDP team to get to primary results as soon as possible.”
About CAPTIVATE
CAPTIVATE is a single, two-part, randomized withdrawal Phase 3 trial of claseprubart in CIDP. In open-label Part A of this trial, participants are administered a loading dose followed by 300mg claseprubart administered every 2 weeks (Q2W) via subcutaneous (S.C.) injection for up to 13 weeks. Part A included an interim responder analysis of a pre-defined number of participants. The primary endpoint in Part A is response as measured as ≥1 point decrease (improvement) in adjusted INCAT score compared to Part A baseline. Only participants who respond to claseprubart in Part A will be randomized into Part B, a double-blind, placebo-controlled treatment period of up to 52 weeks, where they will be assessed for prevention of relapse, safety and tolerability, followed by an open-label extension period. The primary endpoint in Part B is efficacy (time to relapse) as measured as ≥1 point increase in adjusted INCAT. The Company believes this single pivotal trial will support Biologics License Application filing in adult patients with CIDP and expects to provide CAPTIVATE Part B top-line guidance by the end of 2026.
CAPTIVATE Investor Conference Call & Webcast to be Held at 8:00 a.m. ET Today
Dianthus Therapeutics will host an investor call and webcast to discuss the CAPTIVATE trial interim responder analysis today, March 9, 2026 at 8:00 a.m. ET. To access the live conference call by phone, please register here. Conference call participants in the question and answer session should pre-register to receive the dial-in number and personal PIN.
The live webcast may be accessed via the Investors section of the Dianthus Therapeutics website at https://investor.dianthustx.com/. A replay of the webcast will be available following the call. The presentation that will be used on this webcast is available here.
About Claseprubart (DNTH103)
Claseprubart is an investigational, clinical-stage, potent monoclonal antibody engineered to selectively target the classical pathway by inhibiting only the active form of the C1s protein, a clinically validated complement target. Claseprubart is enhanced with YTE half-life extension technology designed to enable a more convenient subcutaneous, infrequently dosed, self-administered injection. Additionally, selective inhibition of the classical complement pathway may lower patient risk of infection from encapsulated bacteria by preserving immune activity of the lectin and alternative pathways. As the classical pathway plays a significant role in disease pathology, claseprubart has the potential to be a best-in-class pipeline-in-a-product across a range of autoimmune disorders with high unmet need. Dianthus is building a neuromuscular franchise with claseprubart and expects to initiate a Phase 3 trial in generalized Myasthenia Gravis in mid-2026, with top-line results expected in the second half of 2028, report top-line data from the Phase 2 MoMeNtum trial in Multifocal Motor Neuropathy in the second half of 2026, and provide an update on timing of top-line data from Part B of the Phase 3 CAPTIVATE trial in Chronic Inflammatory Demyelinating Polyneuropathy by the end of 2026.
Claseprubart is an investigational agent that is not approved as a therapy in any indication in any jurisdiction worldwide.
About CIDP
Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) is an autoimmune and inflammatory disorder affecting the myelin that insulates and protects peripheral nerves. CIDP is estimated to affect more than 40,000 people in the United States. Common symptoms of the disease include weakness, loss of balance, and sensation changes in the arms or legs. In the classic or typical CIDP, there is symmetric involvement of both upper and lower limbs, characterized by weakness in the proximal (for example, shoulder region or hip region) as well as distal (for example, wrist or ankle) muscle groups. In addition, there is sensory involvement. There are several atypical forms of CIDP, characterized by varying levels of motor and sensory involvement with overlap. CIDP follows a relapsing-remitting or a progressive clinical course, which can result in substantial disability, loss of motor and sensory function, and negative impact on quality of life.
About Dianthus Therapeutics
Dianthus Therapeutics, Inc. is a clinical-stage biotechnology company dedicated to developing next-generation therapies to transform the treatment of severe autoimmune diseases. Based in New York City and Waltham, Mass., Dianthus is comprised of an experienced team of biotech and pharma executives who aim to deliver transformative medicines for people living with severe autoimmune and inflammatory diseases.
To learn more, please visit www.dianthustx.com and follow us on LinkedIn.
Contact
Jennifer Davis Ruff
Dianthus Therapeutics
[email protected]