A Phase 2 Proof of Concept Study to Evaluate the Efficacy and Safety of Daxdilimab in Participants With Dermatomyositis (DM) or Anti-synthetase Inflammatory Myositis (ASIM)

NCT05669014 | Completed Phase 2 DMC FDA Drug

• 2 other identifiers: HZNP-DAX-2052022-502810-10-00
• Study Type: interventional
• Target: 12
• Locations: 6 countries
• Sites: 9

Brief Summary

The primary efficacy objective: To evaluate the effect of daxdilimab compared with placebo in reducing disease activity at Week 24. The secondary efficacy objectives include:

1. 1.To evaluate the effect of daxdilimab compared with placebo in reducing disease activity at Week 24.
2. 2.To evaluate the effect of daxdilimab compared with placebo on skin symptoms at Week 24.
3. 3.To evaluate the effect of daxdilimab on decreasing the use of corticosteroid at Week 24.
4. 4.To characterize the pharmacokinetics (PK) and immunogenicity of daxdilimab in participants.
5. 5.To evaluate the safety and tolerability of daxdilimab in participants.

Conditions

Idiopathic Inflammatory Myositis

Keywords

Anti-synthetase syndrome; Myositis; Polymyositis

Outcome Measures

Primary Outcomes (1)

• Efficacy of daxdilimab compared to placebo as measured by Total Improvement Score (TIS)

  TIS is a composite endpoint based on improvement in the 6 Disease Activity Core Set Measure (CSM) scores and range from 0 to 100 (2016 European League Against Rheumatism \[EULAR\]/American College of Rheumatology \[ACR\] Myositis Response Criteria) where a higher score is indicative of more improvement

  At Week 24

Secondary Outcomes (11)

• Proportion of participants with improvement of TIS ≥ 40 and without deterioration at 2 consecutive visits at 24 weeks

  At 24 Weeks

• Proportion of participants with improvement of TIS ≥ 20 and without deterioration at 2 consecutive visits at 24 weeks

  At 24 Weeks

• Change in the cutaneous dermatomyositis disease area and severity index (CDASI) activity score from Baseline (Day 1) to Week 24

  Baseline (Day1) to Week 24

• Proportion of participants on an oral corticosteroid (OCS) dose ≥ 10 mg of prednisone or equivalent at baseline who achieve a clinically meaningful reduction in the OCS dose at Week 24

  Baseline to Week 24

• Serum concentration of daxdilimab over time

  Baseline to Week 56

Study Arms (2)

Daxdilimab

EXPERIMENTAL

Daxdilimab will be administered by subcutaneous (SC) injection during the 24-week treatment period followed by an 8-week safety follow up. Prior to amendment 2 participants could enter an open-label extension period from weeks 24-48. For those participants already in the open-label extension, they will stop dosing and enter the safety follow up.

Drug: Daxdilimab

Placebo

PLACEBO COMPARATOR

Matching placebo will be administered by SC injection during the 24-week treatment period followed by an 8-week safety follow up. Prior to amendment 2 participants could enter an open-label extension period from weeks 24-48 and receive daxdilimab. For those participants already in the open-label extension, they will stop dosing and enter the safety follow up.

Drug: Daxdilimab; Drug: Placebo

Interventions

Daxdilimab DRUG

Participants will be administered daxdilimab by subcutaneous (SC) injection.

Also known as: HZN-7734

Daxdilimab; Placebo

Placebo DRUG

Participants will be administered identically matching placebo by SC injection.

Placebo

Eligibility Criteria

• Age: 18 Years - 75 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Adult men or women 18 and ≤ 75 years of age at the time of signing the informed consent (ICF).
• A diagnosis of definite or probable myositis according to American College of Rheumatology/European League Against Rheumatism 2017 (ACR/EULAR 2017) criteria:
• Population 1: DM
• Diagnosis of DM with DM rash current or historical, or
• Population 2: ASIM
• Anti-histidyl tRNA synthetase-(Anti-Jo-1) antibodies must be positive during screening by central laboratory testing, or
• One of following antibodies must be positive by historical testing: directed against anti-alanyl- (anti-PL-12), anti-threonyl-(anti PL-7), anti-asparaginyl-(anti-KS), anti-glycyl-(anti-EJ), anti-isoleucyl-(anti-OJ), anti-phenylalanyl-transfer RNA synthetase-(anti-ZO), anti-tyrosil-YRS(HA).
• Currently active myositis with all the following (a, b, and c) during screening:
• Manual Muscle Testing (MMT 8) score \< 142
• At least 2 other abnormal core set measures (CSM) from the following list:
• Patient global disease activity (PtGDA) ≥ 2 cm in a 10 cm visual analog scale (VAS)
• Physician's Global Disease Activity (PhGDA) ≥ 2 cm in a 10 cm VAS
• Extramuscular activity ≥ 2cm in a 10 cm VAS
• At least one muscle enzyme 1.5 times upper limit of normal (ULN)
• Health assessment questionnaire-disability index (HAQ-DI) ≥ 0.5

You may not qualify if:

• Any condition that, in the opinion of the investigator or sponsor, would interfere with the evaluation of investigational product (IP) or interpretation of participant safety or study results.
• Weight \> 160 kg (352 pounds) at screening.
• Breastfeeding or pregnant women or women who intend to become pregnant anytime from signing the ICF through 6 months after receiving the last dose of IP.
• History of clinically meaningful cardiac disease including unstable angina, myocardial infarction, congestive heart failure within 6 months prior to randomization; arrhythmia requiring active therapy, except for clinically insignificant extra systoles, or minor conduction abnormalities; or presence of clinically meaningful abnormality on electrocardiogram (ECG) if, in the opinion of the Investigator, it would increase the risk of study participation.
• History of cancer within the past 5 years except cutaneous basal cell or squamous cell carcinoma treated with curative therapy.
• Any underlying condition that in the opinion of the Investigator significantly predisposes the participant to infection (eg. hepatitis C).
• Known history of a primary immunodeficiency or an underlying condition, such as known human immunodeficiency virus (HIV) infection, or a positive result for HIV infection per central laboratory.
• All participants will undergo testing for hepatitis B virus serology as defined in the protocol.
• Active tuberculosis (TB), or a positive interferon gamma (IFN-γ) release assay (IGRA) test at screening, unless documented history of appropriate treatment for active or latent TB according to local guidelines.
• Any severe herpes virus family infection (including Epstein-Barr virus, cytomegalovirus \[CMV\]) at any time prior to randomization.
• Opportunistic infection requiring hospitalization or parenteral antimicrobial treatment within 2 years prior to randomization.
• Significant organ system involvement or myositis damage (global muscle damage score \> 5 on a 10 cm VAS scale on the MDI) that poses risks in the study or impedes assessments.
• Current musculoskeletal, joint, or inflammatory disease, including significant joint contractures or calcinosis that in the opinion of the investigator, could interfere with the muscle strength assessments and confound the disease activity assessments.
• Wheelchair bound participants.
• Current inflammatory skin disease other than DM or ASIM that, in the opinion of the investigator, could interfere with the inflammatory skin assessments or confound the disease activity assessments.

Sponsors & Collaborators

• Amgen: lead

Study Sites (9)

Advanced Research Center, Inc.

Anaheim, California, 92805-5854, United States

Location

Centro Mineiro de Pesquisa - CMiP

Juiz de Fora, Minas Gerais, 36010-570, Brazil

Location

LMK Servicos Medicos SS

Porto Alegre, Rio Grande do Sul, 90480-000, Brazil

Location

Revmatologicky ustav

Prague, Praha, Hlavní Mesto, 128 00, Czechia

Location

Unidad de Investigacion de las Enfermedades Reumaticas S.A. De C.V.

Mexico City, Mexico

Location

Accelerium, S. de R.L. de C.V. - PPDS

Monterrey, 64000, Mexico

Location

Hospital Quironsalud Infanta Luisa

Seville, 41010, Spain

Location

Aintree University Hospital - NWCRN - PPDS

Liverpool, Merseyside, L9 7AL, United Kingdom

Location

Western General Hospital Edinburgh - PPDS

Edinburgh, Midlothian, EH4 2XU, United Kingdom

Location

Related Links

• AmgenTrials clinical trials website

MeSH Terms

Conditions

Myositis; Polymyositis

Condition Hierarchy (Ancestors)

Muscular Diseases; Musculoskeletal Diseases; Neuromuscular Diseases; Nervous System Diseases

Study Officials

• MD

  Amgen

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, INVESTIGATOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: December 20, 2022
• First Posted: December 30, 2022
• Study Start: December 4, 2023
• Primary Completion: July 2, 2025
• Study Completion: July 2, 2025
• Last Updated: November 3, 2025

Record last verified: 2025-10

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF, CSR
• Time Frame: Data sharing requests relating to this study will be considered beginning 18 months after the study has ended and either 1) the product and indication have been granted marketing authorization in both the US and Europe or 2) clinical development for the product and/or indication discontinues and the data will not be submitted to regulatory authorities. There is no end date for eligibility to submit a data sharing request for this study.
• Access Criteria: Qualified researchers may submit a request containing the research objectives, the Amgen product(s) and Amgen study/studies in scope, endpoints/outcomes of interest, statistical analysis plan, data requirements, publication plan, and qualifications of the researcher(s). In general, Amgen does not grant external requests for individual patient data for the purpose of re-evaluating safety and efficacy issues already addressed in the product labelling. Requests are reviewed by a committee of internal advisors. If not approved, a Data Sharing Independent Review Panel will arbitrate and make the final decision. Upon approval, information necessary to address the research question will be provided under the terms of a data sharing agreement. This may include anonymized individual patient data and/or available supporting documents, containing fragments of analysis code where provided in analysis specifications. Further details are available at the URL below.

Locations

ES (1); GB (2); US (1); CZ (1); BR (2); ME (2)