M23-698 (Hidradenitis Suppurativa)

This study is divided into 5 periods:

• Screening period
• Study drug administration Period 1
• Study drug administration Period 2
• Study drug administration Period 3
• Follow-up period

If you decide to join this study, we will determine your eligibility during the screening period. This period lasts about 5 weeks and involves the following procedures:

Physical exam

Blood draws

Skin exam

Questionnaires

If you are eligible to join based on screening, you will proceed to study drug administration Period 1 and get a random assignment (like a coin flip) to either take a 30 mg dose of the study drug each day or to take a placebo (inactive substance that has no drug in it). This is a "blinded" study and you will not know if you are using the study drug or placebo. Study drug administration Period 1 will last for 16 weeks. When Period 1 ends, you will begin Period 2. During Period 2, one of the following will occur:

• If you were taking the placebo during Period 1, you might be switched to a 30 mg dose of the study drug or you might continue to take the placebo.
• If you were taking the study drug during Period 1, you might be switched to a 15 mg dose of the study drug or you might continue to take the 30 mg dose.

Period 2 will last for 20 weeks. You will continue to be blinded during this portion of the study and will not know if you are using the study drug or placebo. Period 3 will begin at the end of Period 2. At the beginning of Period 3, you and the study doctor will determine whether or not your skin has improved. If there has been no improvement or you feel like your symptoms are worse, you will stop taking the study drug or placebo. Otherwise, you will continue to take your blinded regimen until you reach the 1-year mark of taking the study drug or placebo. At the 1-year mark of beginning the study drug or placebo (16th week of Period 3), the study will become "open label." At this point, all participants, including those who stopped their regimen at the beginning of Period 3, will start taking a 30 mg dose of the study drug no matter what their regimen was before this point. The open label portion of Period 3 will last for 1 year, which means that Period 3 lasts for 68 weeks altogether. During the open label portion, the study doctor might lower your dose from 30 mg to 15 mg if they believe that you are doing well and do not need the higher dose of the study drug. The follow-up period begins after Period 3 is finished. We will schedule you to visit our clinic one more time and keep in touch with you for at least a month to see how you are doing.