This is a study to evaluate the long-term safety, tolerability, and efficacy of sonelokimab in participants with moderate to severe hidradenitis suppurativa who were previously enrolled in a parental study.

Inclusion Criteria:

• Participants who have completed a parental study (M1095-HS-301 or M1095-HS-302 [adult studies] or M1095-HS-304 [adolescent study]) and are eligible to continue to receive sonelokimab at the time of completing the parental study.
• Female participants are eligible to participate if they are not pregnant or breastfeeding
• Male participants must be willing to use a condom when sexually active with a partner of childbearing potential . Male participants must also agree to refrain from donating sperm during the study and for at least 8 weeks after the last dose of study treatment.

Exclusion Criteria:

• Participants who meet any of the discontinuation criteria of the parental study at the time of enrollment in this OLE study.
• Participants who have ongoing or planned to use one or more of the prohibited HS or non-HS treatments specified in the protocol.
• Participants who plan to participate in another interventional study for a drug or device during this study.