A Study to Assess the Long-term Safety and Efficacy of a Subcutaneous Formulation of Efgartigimod in Adults With Active Idiopathic Inflammatory Myopathy

To join this study, you must be an adult aged 18 or older and have previously taken part in a specific trial called ARGX-113-2007. You should be able to understand the study details and give your official consent to participate.

There are also some reasons why you might not be able to join. For example, if you plan to have major surgery during the study, or if you've developed a serious medical condition since the last study that the doctors think would make it risky for you to participate or affect the study results. You also can't take part if you are allergic to the study medicine or any of its ingredients, or if you've developed any new or returning cancer (other than a common type of skin cancer).

If you decide to join this study, you will receive the study medication, efgartigimod, as an injection under your skin regularly for up to 51 months (about 4 years and 3 months). During this time, you will have regular visits to the clinic so doctors can monitor your health and how the medication is affecting you. After you finish taking the medication, there will be a follow-up period of about 8 weeks (56 days) where your health will continue to be checked to ensure your safety. The total duration of your involvement could be up to 53 months, including the treatment and follow-up periods.