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| ID | Type | Description | Link |
|---|---|---|---|
| 2026-525298-38-00 | EU Trial (CTIS) Number |
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The purpose of this Phase 3 study is to demonstrate the efficacy, safety, and tolerability of claseprubart in participants with generalized myasthenia gravis (gMG).
The study includes the following periods:
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Placebo | Placebo Comparator | Intravenous (IV) infusion of Placebo on Day 1 followed by subcutaneous (SC) injections of Placebo every 2 weeks (Q2W) starting at Week 1 (Day 8). |
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| Claseprubart Q2W | Experimental | IV loading dose of claseprubart on Day 1 followed by SC injections of claseprubart Q2W starting at Week 1 (Day 8). |
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| Claseprubart Every 4 weeks (Q4W) | Experimental | IV loading dose of claseprubart on Day 1 followed by SC injections of claseprubart or Placebo Q2W starting at Week 1 (Day 8), with doses alternating between claseprubart and placebo. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Claseprubart | Drug | IV loading dose on Day 1 |
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| Measure | Description | Time Frame |
|---|---|---|
| Change from Baseline to Week 17 in Myasthenia Gravis Activities of Daily Living (MG-ADL) Scale Score | 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 17 |
| Measure | Description | Time Frame |
|---|---|---|
| Change from Baseline to Week 17 in Quantitative Myasthenia Gravis (QMG) Scale Score | 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 17 |
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Inclusion Criteria:
Must have given written informed consent before any study-related activities are carried out
Weight range between 40-130 kg at Screening
Diagnosis of gMG by the following tests:
i. History of abnormal neuromuscular transmission test; ii. History of positive anticholinesterase test; iii. Clinical response to acetylcholinesterase inhibitors.
Myasthenia Gravis Foundation of America (MGFA) Class II-IVa
MG-ADL scale score of 6 or more
QMG scale score of 10 or more
Documented vaccinations against encapsulated bacteria in accordance with local requirements and based on vaccine availability
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
Male participants agree not to donate sperm and, if engaging in sexual intercourse with a female partner who could become pregnant, must agree to use an acceptable method of contraception
Exclusion Criteria:
History or presence of significant medical/surgical condition including any acute illness, mental illness, or major surgery considered to be clinically significant or that could have potential impact on safety/efficacy or study procedures
Known complement deficiency
Prior history (at any time) of N. meningitidis infection
Participants with known seropositivity or who test positive for an active viral infection with human immunodeficiency virus (HIV-1 or HIV-2), hepatitis B (HBV; except participants who are seropositive because of HBV vaccination) or hepatitis C virus (HCV) during Screening
Previous treatment with claseprubart (DNTH103) or participation in a clinical trial with claseprubart. [
Any thymic surgery/biopsy within 1 year of Screening
Any known or untreated thymoma.
Any history of thymic carcinoma or thymic malignancy
History of active malignancy within 5 years prior to Screening, except basal cell carcinoma of the skin, curatively resected squamous cell carcinoma of the skin, cervical carcinoma in situ curatively treated or low-grade prostate adenocarcinoma for which appropriate management is observation alone
Concurrent or previous use of the following medication within the time periods specified below.
Participation in another clinical study of an investigational drug within 90 days or 5 half-lives of the investigational agent
Diagnosis of systemic lupus erythematosus (SLE) or family history (defined as a parent, sibling, or child) of SLE](streamdown:incomplete-link)
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Dianthus Clinical Contact Center | Contact | 929-999-4055 | clinicaltrials@dianthustx.com |
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Cinical Study Site | Recruiting | Fayetteville | North Carolina | 28304 | United States |
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| ID | Term |
|---|---|
| D009157 | Myasthenia Gravis |
| ID | Term |
|---|---|
| D020361 | Paraneoplastic Syndromes, Nervous System |
| D009423 | Nervous System Neoplasms |
| D009371 | Neoplasms by Site |
| D009369 | Neoplasms |
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| Placebo | Drug | IV infusion on Day 1 |
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| Claseprubart | Combination Product | Prefilled syringe containing claseprubart for SC administration |
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| Placebo | Combination Product | Prefilled syringe containing placebo for SC administration |
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| Change from Baseline to Week 17 in Myasthenia Gravis Composite (MGC) Scale Score | 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 17 |
| Proportion of Participants with Greater Than or Equal to (≥) a 5-point Reduction in MG-ADL Scale Score at Week 17 Compared to Baseline | Baseline (Day 1) to Week 17 |
| Proportion of Participants Who Reach Minimal Symptom Expression (MSE), Defined as MG-ADL 0 or 1 at Week 17, Without Use of Rescue Therapy | Baseline (Day 1) to Week 17 |
| Proportion of Participants with a ≥ 5-point Reduction in QMG Scale Score at Week 17 Compared to Baseline | Baseline (Day 1) to Week 17 |
| Incidence of Treatment-emergent Adverse Events (TEAEs) and Treatment-Emergent and Treatment-Emergent Serious Adverse Events (SAEs) in the RCT period, BEP, OLE, and Safety Follow-Up | Number of participants with TEAEs and treatment-emergent SAEs will be reported. | Baseline (Day 1) through Safety Follow-Up period (up to approximately 161 weeks) |
| Serum Concentrations of Claseprubart | Blood samples will be collected for measurement of serum concentrations of claseprubart at various timepoints both pre- and post-dose. | Baseline (Day 1) through Safety Follow-Up period (up to approximately 161 weeks) |
| Change from Baseline in Complement Total Blood Test (CH50) in Serum ex vivo | Blood samples will be collected to determine changes in CH50 at various timepoints. | Baseline (Day 1) through Safety Follow-Up period (up to approximately 161 weeks) |
| Incidence of Antidrug Antibody (ADAs) Against Claseprubart in the RCT Period, BEP, OLE, and Safety Follow-Up | Blood samples will be collected to measure ADA against claseprubart at various timepoints. | Baseline (Day 1) through Safety Follow-Up period (up to approximately 161 weeks) |
| Titer of ADAs Against Claseprubart in the RCT Period, BEP, OLE, and Safety Follow-Up | Blood samples will be collected to measure ADA against claseprubart at various timepoints. | Baseline (Day 1) through Safety Follow-Up period (up to approximately 161 weeks) |
| D010257 | Paraneoplastic Syndromes |
| D020274 | Autoimmune Diseases of the Nervous System |
| D009422 | Nervous System Diseases |
| D019636 | Neurodegenerative Diseases |
| D020511 | Neuromuscular Junction Diseases |
| D009468 | Neuromuscular Diseases |
| D001327 | Autoimmune Diseases |
| D007154 | Immune System Diseases |