About the Flex Study

The purpose of the Flex Study is to evaluate the effectiveness and safety of an investigational medication compared to standard of care on reducing symptoms in adults with DM.

Who May Qualify

Eligible participants must:

  • Be male or female at least 18 years of age
  • Have a diagnosis of DM
  • Have had an inadequate response or be intolerant to two or more DM treatments
    • Those who are currently receiving treatment with glucocorticoids or immunosuppressive therapies (ISTs) may be eligible to participate if they are on a stable dose entering the study or complete a washout period (this will depend on the treatment)
  • Not have cancer-associated myositis (defined as the diagnosis of myositis within three years of the diagnosis of cancer)

There are additional eligibility requirements that the study doctor can explain to you.

About the Investigational Medication

The investigational medication is called ravulizumab. “Investigational” means that it has not been approved by country-specific regulatory health authorities to be used for DM and its use is being allowed for research purposes only. Participants will be assigned at random to receive either the investigational medication or the placebo. Neither the participant nor the study team will know which study treatment option has been assigned, but in case of an emergency, they can quickly find out. Both the investigational medication and the placebo are administered as intravenous (IV) infusions.

Study Participation

The total duration of the Flex Study is between 104 and 128 weeks and consists of:


This period lasts up to four weeks. During this time, the study staff reviews a potential participant’s medical history and performs tests to see if they qualify for the study.

Study Treatment period

Participants are enrolled in either Part A or Part B and selected at random to receive either the investigational medication (ravulizumab) or a placebo, which looks just like the investigational medication but contains no active ingredients. The study doctor collects blood and urine samples and performs assessments during study site visits to check on participants’ health.

  • Part A lasts 26 weeks and includes five visits to the study site
  • Part B lasts 50 weeks and includes eight visits to the study site

Open-label extension period

If a participant is eligible to continue taking the investigational medication, the study doctor will discuss the option of participating in the open-label extension period. This period may last up to 74 weeks (one and a half years) or until the investigational medication is approved in the US, whichever occurs first, and includes 11 visits to the study site.

Throughout the study, the study doctor may perform a number of tests and procedures, including but not limited to:

  • Medical history review
  • Physical exam
  • Vital sign measurement
  • DM symptoms and muscle strength assessment
  • Pregnancy test (if applicable)
  • Blood and urine sample collections

See if you may qualify