The purpose of the study is to assess the PK of bimekizumab following subcutaneous (sc) administration in study participants with moderate to severe hidradenitis suppurativa (HS)
Study participant must be 12 to <18 years of age at the time of informed consent/assent, at Tanner stage 2 or more, for the first 8 participants only, followed by also including participants ≥9 to <18 years of age at Tanner stage 2 or more.
Study participant must have a diagnosis of HS for at least 6 months prior to the Baseline Visit.
Study participant must have moderate to severe HS, defined as a total of ≥5 inflammatory lesions (ie, the sum of abscesses and inflammatory nodules), as assessed at both the Screening and Baseline Visits.
Study participant must have HS lesions present in at least 2 distinct anatomic areas, 1 of which must be at least Hurley Stage II or III, as assessed at both the Screening and Baseline Visits.
Study participant has a draining tunnel count of >20 at either the Screening or Baseline Visits.
Study participant has experienced primary failure (no response within 12 weeks) to 1 or more IL 17 biologic response modifiers (eg, brodalumab, ixekizumab, secukinumab) OR primary failure to more than 1 biologic response modifier other than an IL-17 biologic response modifier.
Study participant has previously participated in this study or has received previous therapy with bimekizumab.
Study participant has a history of IBD or symptoms suggestive of IBD.