What is this study about?
The main goal of this study is to look at the effect (efficacy) and the safety of an investigational study drug compared to placebo (a treatment that looks like the investigational study drug and is given the same way, but has no active ingredients) in adults with active idiopathic inflammatory myopathy, commonly known as myositis. People with the disease subtypes of polymyositis (PM), dermatomyositis, juvenile dermatomyositis (diagnosed within last 5 years), antisynthetase syndrome (ASyS), necrotizing myopathy and PM overlap with Sjögren’s syndrome will be included in the study.
The investigational study drug is currently not approved for use in myositis by any regulatory agency, as its safety and effectiveness have not been established for the treatment of myositis.

Who can take part?
Participants must be adults, aged 18 or over, with a confirmed diagnosis of myositis: polymyositis (PM), dermatomyositis, juvenile dermatomyositis (diagnosed within last 5 years), antisynthetase syndrome (ASyS), necrotizing myopathy and PM overlap with Sjögren’s syndrome. Participants must not be pregnant or planning to become pregnant during the study.

What is the investigational study drug?
In some diseases, the immune system can mistakenly attack the body’s own cells. The investigational study drug is a compound that is being investigated in the ALKIVIA study for its use in treating patients with severe autoimmune diseases.
The investigational study drug is currently not approved for use in myositis by any regulatory agency, as its safety and effectiveness have not been established for the treatment of myositis.

What are the chances of getting the investigational study drug?
At the first scheduled visit of the Treatment Period, participants will be randomly assigned (by chance, like the flip of a coin) to receive either the investigational study drug (active) or a placebo (inactive). A computer system will flip the coin. Participants have 1 chance out of 2 to receive the investigational study drug. Therefore, participants have 1 chance out of 2 to receive placebo. No one will know which study drug participants will receive, not even the study doctor. If needed, the study doctor can find this out.

What is involved in taking part in the ALKIVIA study?
First, participants will be asked to come into a study site for screening, where they will be examined, receive testing and be asked questions (screening assessments) to see if the study is appropriate.
During the Treatment Period, which begins when participants receive their first dose of investigational study drug or placebo, there will be 7 scheduled visits to the study site, once every 4 weeks. On average, each visit to the study site will take about 3 to 4 hours. Participants will receive a subcutaneous injection, delivered into the layer beneath the skin, of either the investigational study drug or placebo every week, except at their final treatment visit (visit 7). At the scheduled visits, the study staff will administer the injection. In between scheduled visits, participants can receive the injection at the study site or be given it at home by a home nurse, or by themselves or their caregiver (if trained).
During the study, participants will continue to take their current medicines for myositis.

Will there be any costs associated with participation in the study?
There will be no costs associated with participation in the study. Participants will receive the study drug, tests, examinations, and medical care related to the study at no charge. Participants may also be reimbursed for travel to and from the study center for study visits.

What happens after the treatment period is completed?
If participants complete the study, they can choose to enter a Safety Follow-Up Extension Study, where all participants receive the investigational study drug (no placebo). If participants do not wish to enter the Safety Follow-Up Extension Study, or are not eligible to do so, they will be followed up for 8 weeks (1 visit) after the final subcutaneous injection of either the investigational study drug or placebo, for safety purposes.

How do I find out more about participating in the ALKIVIA study?
If you are interested in taking part in the ALKIVIA study and would like more information about participating, email us at clinicaltrials@argenx.com and a member of the ALKIVIA patient support team will contact you.