A Phase 2 Study to Evaluate DNTH103 in Adults With Generalized Myasthenia Gravis (MAGIC) (MAGIC)

July 23, 2026 updated by: Dianthus Therapeutics

A Phase 2, Randomized, Blinded, Placebo-Controlled, Study to Evaluate Safety, Tolerability, Pharmacometrics, and Efficacy of DNTH103 in Adults With Generalized Myasthenia Gravis (MAGIC)

The purpose of this Phase 2 study is to evaluate the safety, tolerability, pharmacometrics, and efficacy of DNTH103 in participants with generalized myasthenia gravis (gMG).

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Detailed Description

The study includes the following periods:

  • Screening (up to 10 weeks)
  • Randomized, blinded, controlled treatment (RCT) period (13 weeks)
  • Open-label extension (OLE) period (optional) for eligible participants (104 weeks)
  • Safety follow-up (SFU) (40 weeks)

Study Type

Interventional

Enrollment (Actual)

65

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Argentina
      • Buenos Aires, Argentina, 20/11/1902
        • Clinical Study Site
      • Buenos Aires, Argentina, C1012AAR
        • Clinical Study Site
      • Buenos Aires, Argentina, C1015ABR
        • Clinical Study Site
      • Córdoba, Argentina, X5004CDT
        • Clinical Study Site
      • Rosario, Argentina, 2000
        • Clinical Study Site
    • Tucumán Province
      • San Miguel de Tucumán, Tucumán Province, Argentina, T4000
        • Clinical Study Site
  • Canada
    • Ontario
      • London, Ontario, Canada, N6A 5W9
        • Clinical Study Site
  • Czechia
      • Ostrava, Czechia, 70852
        • Clinical Study Site
  • Denmark
      • Copenhagen, Denmark, 02100
        • Clinical Study Site
  • France
      • Bordeaux, France, 33076
        • Clinical Study Site
      • Nice, France, 06001
        • Clinical Study Site
      • Strasbourg, France, 67000
        • Clinical Study Site
  • Israel
      • Haifa, Israel, 3109601
        • Clinical Study Site
      • Ramat Gan, Israel
        • Clinical Study Site
      • Safed, Israel, 13100
        • Clinical Study Site
  • Italy
      • Milan, Italy, 20133
        • Clinical Study Site
      • Naples, Italy, 80131
        • Clinical Study Site
      • Pisa, Italy, 56126
        • Clinical Study Site
      • Rome, Italy, 00168
        • Clinical Study Site
      • Rome, Italy, 00189
        • Clinical Study Site
  • Netherlands
      • Amsterdam, Netherlands
        • Clinical Study Site
  • North Macedonia
      • Skopje, North Macedonia, 1000
        • Clinical Study Site
  • Norway
      • Bergen, Norway, 5021
        • Clinical Study Site
  • Poland
      • Bydgoszcz, Poland, 85-065
        • Clinical Study Site
      • Katowice, Poland, 40123
        • Clinical Study Site
      • Krakow, Poland, 31-503
        • Clinical Study Site
      • Krakow, Poland, 31-202
        • Clinical Study Site
      • Lublin, Poland, 20-093
        • Clinical Study Site
      • Warsaw, Poland, 01-684
        • Clinical Study Site
      • Warsaw, Poland, 02-657
        • Clinical Study Site
  • Serbia
      • Belgrade, Serbia, 11000
        • Clinical Study Site
      • Kragujevac, Serbia, 34000
        • Clinical Study Site
      • Niš, Serbia, 18000
        • Clinical Study Site
      • Novi Sad, Serbia, 21000
        • Clinical Study Site
  • Sweden
      • Malmö, Sweden
        • Clinical Study Site
  • United States
    • Arizona
      • Phoenix, Arizona, United States, 85028
        • Clinical Study Site
    • California
      • Irvine, California, United States, 92868
        • Clinical Study Site
    • Connecticut
      • Stamford, Connecticut, United States, 06905
        • Clinical Study Site
    • Florida
      • Boca Raton, Florida, United States, 33487
        • Clinical Study Site
      • Bradenton, Florida, United States, 34205
        • Clinical Study Site
      • Maitland, Florida, United States, 32751
        • Clinical Study Site
      • Tampa, Florida, United States, 33620
        • Clincal Study Site
    • Illinois
      • O'Fallon, Illinois, United States, 62269
        • Clinical Study Site
    • Kansas
      • Kansas City, Kansas, United States, 66103
        • Clinical Study Site
    • Kentucky
      • Lexington, Kentucky, United States, 40503
        • Clinical Study Site
    • Massachusetts
      • Boston, Massachusetts, United States, 02215
        • Clinical Study Site
    • Michigan
      • East Lansing, Michigan, United States, 48824
        • Clinical Study Site
    • Missouri
      • Columbia, Missouri, United States, 65212
        • Clinical Study Site
    • Ohio
      • Cincinnati, Ohio, United States, 45219
        • Clinical Study Site
      • Columbus, Ohio, United States, 43221
        • Clinical Study Site
    • Texas
      • Dallas, Texas, United States, 75206
        • Clinical Study Site
      • Dallas, Texas, United States, 75243
        • Clinical Study Site
      • Houston, Texas, United States, 77030
        • Clinical Study Site
      • Houston, Texas, United States, 77030
        • Clinical Study Site #2
      • Lubbock, Texas, United States, 79414
        • Clinical Study Site
    • Virginia
      • Richmond, Virginia, United States, 23219
        • Clinical Study Site

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Must have given written informed consent before any study-related activities are carried out.
  2. Adult males and females, 18 to 75 years of age (inclusive) at Screening.
  3. Weight range between 40-120 kg at Screening.

  4. Diagnosis of gMG by the following tests:

    Acetylcholine receptor antibody (AChR Ab) positive, and

    One of the following:

    i. History of abnormal neuromuscular transmission test; ii. History of positive anticholinesterase test; iii. Clinical response to acetylcholinesterase inhibitors.

  5. Myasthenia Gravis Foundation of America (MGFA) Class II-Iva
  6. Myasthenia Gravis Activities of Daily Living (MG-ADL) score of 6 or more
  7. Vaccination against N. meningitidis with the quadrivalent meningococcal vaccine, and where available, meningococcal serotype B vaccine within 3 years prior to, or at the time of, initiating study drug.

  8. Female participants must:

    Be of non-childbearing potential, or if of childbearing potential, must agree not to donate ova, not to attempt to become pregnant and, if engaging in sexual intercourse with a male partner, must agree to use a highly effective method of contraception.

  9. Male participants must be surgically sterile for at least 90 days prior to screening or agree not to donate sperm

Exclusion Criteria:

  1. History or presence of significant medical/surgical condition including any acute illness or major surgery considered to be clinically significant
  2. Prior history (at any time) of N. meningitidis infection.
  3. Positive test results for active human immunodeficiency virus (HIV-1 or HIV-2), hepatitis B surface antigen (HBsAg), or hepatitis C virus (HCV) antibodies during Screening.
  4. Any thymic surgery/biopsy within 1 year of Screening.
  5. Any known or untreated thymoma.
  6. Any history of thymic carcinoma or thymic malignancy.

  7. Concurrent or previous use of the following medication within the time periods specified below.

    1. Rituximab within 6 months (180 days) prior to randomization (Day 1);
    2. Intravenous immunoglobulin (IVIg) and plasma exchange (PLEX) within 4 weeks (28 days) prior to randomization (Day 1).
  8. Participation in another clinical study of an investigational drug within 90 days or 5 half-lives of the investigational agent.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Placebo Comparator: Placebo
Drug: Placebo
Day 1: IV infusion of placebo Week 1 to Week 11: placebo administered SC every 2 weeks
Experimental: Claseprubart 300 mg Q2W
Drug: Claseprubart
Day 1: IV loading dose Week 1 to Week 11: Claseprubart administered SC every 2 weeks
Other Names:
  • DNTH103
Experimental: Claseprubart 600 mg Q2W
Drug: Claseprubart
Day 1: IV loading dose Week 1 to Week 11: Claseprubart administered SC every 2 weeks
Other Names:
  • DNTH103

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Incidence of Treatment-Emergent Adverse Events (TEAEs) and Treatment-Emergent Serious Adverse Events (SAEs)
Time Frame: Baseline (Day 1) to Week 13
Number of participants with TEAEs and treatment-emergent SAEs will be reported.
Baseline (Day 1) to Week 13

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change from Baseline in Myasthenia Gravis Activities of Daily Living (MG-ADL) Scale Score
Time Frame: Baseline (Day 1) to Week 13
The MG-ADL score is an 8-item patient reported outcome (PRO) instrument. The MG-ADL targets symptoms of disability across ocular, bulbar, respiratory, and axial symptoms. The item responses are scored from 0 to 3, and the total score of the MG-ADL is the sum of the 8 items and ranges from 0 to 24, with a higher score indicating more disability.
Baseline (Day 1) to Week 13
Change from Baseline in Quantitative Myasthenia Gravis (QMG) Scale Score
Time Frame: Baseline (Day 1) to Week 13
The QMG is a clinician-reported assessment to evaluate muscle strength. The QMG consists of 13 items that measure endurance or fatiguability, with each item having a possible score that ranges from 0 - 3. The total possible QMG scores range from 0 - 39, with a higher score indicating greater disease burden.
Baseline (Day 1) to Week 13
Change from Baseline to Week 13 in Myasthenia Gravis Composite (MGC) Scale Score
Time Frame: Baseline (Day 1) to Week 13
The MGC is a validated assessment tool for measuring clinical status of participants with MG. The range of total MGC score is 0 to 50, with higher scores indicating more severe disease. A clinically meaningful improvement is reflected by a 3-point improvement in MGC score. The MGC assesses 10 important functional areas most frequently affected by MG and the scales are weighted for clinical significance that incorporates patient-reported outcomes.
Baseline (Day 1) to Week 13
Incidence of TEAEs and Treatment-Emergent SAEs
Time Frame: Through OLE completion, an average of 117 weeks
Number of participants with TEAEs and treatment-emergent SAEs will be reported.
Through OLE completion, an average of 117 weeks
Serum Concentrations of Claseprubart
Time Frame: Baseline (Day 1) through end of SFU, for a maximum of 197 weeks
Blood samples will be collected for measurement of serum concentrations of claseprubart at various timepoints both pre- and post-dose.
Baseline (Day 1) through end of SFU, for a maximum of 197 weeks
Change from Baseline in Complement Total Blood Test (CH50)
Time Frame: Baseline (Day 1) through end of SFU, for a maximum of 197 weeks
Blood samples will be collected to determine changes in CH50 at various timepoints.
Baseline (Day 1) through end of SFU, for a maximum of 197 weeks
Incidence and Titer of Antidrug Antibody (ADAs) Against Claseprubart
Time Frame: Baseline (Day 1) through end of SFU, for a maximum of 197 weeks
Blood samples will be collected to measure ADA against claseprubart at various timepoints.
Baseline (Day 1) through end of SFU, for a maximum of 197 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Dianthus Therapeutics

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

February 23, 2024

Primary Completion (Actual)

July 28, 2025

Study Completion (Estimated)

October 1, 2028

Study Registration Dates

First Submitted

December 15, 2023

First Submitted That Met QC Criteria

February 20, 2024

First Posted (Actual)

February 28, 2024

Study Record Updates

Last Update Posted (Actual)

July 27, 2026

Last Update Submitted That Met QC Criteria

July 23, 2026

Last Verified

July 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • DNTH103-MG-201
  • 2024-512865-15-00 (Ctis)

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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