The study was not stopped due to safety reasons

Primary Objectives:

1. The primary efficacy objective is to assess the efficacy of 52 weeks of open-label treatment with HZN-825 in participants with diffuse cutaneous systemic sclerosis, as measured by change from both baselines in forced vital capacity percent (FVC %) predicted.
2. The primary safety objective is to examine the safety and tolerability of 52 weeks of open-label treatment with HZN-825, inclusive of, but not limited to, adverse events (AEs), serious AEs (SAEs) and the adverse event of special interest (AESI), from Day 1 to 4 weeks after last dose.

This is an open-label, repeat-dose, multicenter extension trial of HZNP-HZN-825-301. Participants who complete the double-blind Treatment Period (Week 52) in Trial HZNP-HZN-825-301 will be eligible to enter this 52-week extension trial. Participants entering this extension trial will complete the Week 52 Visit activities in HZNP-HZN-825-301 and will not complete the Safety Follow-up Visit 4 weeks after the last dose of trial drug in HZNP-HZN-825-301.

Acquired from Horizon in 2024.

Key Inclusion Criteria:

1. Completed the double-blind Treatment Period (Week 52) in Trial HZNP-HZN-825-301; participants prematurely discontinued from trial drug in Trial HZNP-HZN-825-301 for reasons other than safety or toxicity can be included at the discretion of the Investigator after completing Trial HZNP-HZN-825-301 scheduled visits, including Week 52 assessments.

Key Exclusion Criteria:

1. Anticipated use of another investigational agent for any condition during the course of the trial.
2. New diagnosis of malignant condition after enrolling in Trial HZNP-HZN-825-301 (except successfully treated basal/squamous cell carcinoma of the skin or cervical cancer in situ).
3. Women of childbearing potential (WOCBP) or male participants not agreeing to use highly effective method(s) of birth control throughout the trial and for 4 weeks after last dose of trial drug as defined in the protocol.
4. Any new development with the participant's disease or condition or any significant laboratory test abnormality during the course of Trial HZNP-HZN-825-301 that, in the opinion of the Investigator, would potentially put the subject at unacceptable risk.
5. Pregnant or lactating women.
6. Participants will be ineligible if, in the opinion of the Investigator, they are unlikely to comply with the trial protocol or have a concomitant disease or condition that could interfere with the conduct of the trial.

De-identified individual patient data for variables necessary to address the specific research question in an approved data sharing request.

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.

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.

The Clinical Trial Agreement generally does not restrict an investigator's discussion of trial results after completion. The Agreement permits Amgen a limited period of time to review material discussing trial results (typically up to 45 days and possible extension). Amgen may remove confidential information, but authors have final control and approval of publication content. For multicenter studies, the investigator agrees not to publish any results before the first multi-center publication.