after joining the study you will be assigned to one of the treatment groups by chance. this is called randomised assignment. the study is double‑blind, meaning you and the study staff will not know whether you receive the active drug or a matching placebo. you will receive a film‑coated tablet that looks the same in each group.

the active medication is called nerandomilast (identified as BI 1015550). it is taken by mouth as a film‑coated tablet. depending on the randomised group you will take either 36 mg or 18 mg once daily. if you are assigned to the placebo group you will take a tablet that contains no active substance but has the same size, weight, colour and shape. you will continue to take the assigned tablet every day for up to 52 weeks unless you stop the study early.

you will attend scheduled clinic visits where the study team will check your health status and collect data. the first visit occurs shortly after you start the medication (baseline). a major assessment is performed at week 52 to evaluate changes in disease measures. additional visits may be required if the study team needs information about safety or disease progression.

the study continues for up to 52 weeks. it will end for you either after completing the 52‑week period, or earlier if a confirmed disease progression, a serious health event, or death occurs. at the end of the study you will stop taking the study medication and the study team will perform a final assessment.