This clinical trial is focused on studying the long-term effects of a treatment for Hidradenitis Suppurativa, a skin condition that causes painful lumps under the skin, often in areas like the armpits and groin. The treatment being tested is called bimekizumab, which is given as a solution for injection. Bimekizumab is also known by its code name, UCB4940. The purpose of the study is to evaluate the safety of using bimekizumab over an extended period in adults with moderate to severe cases of this condition.

Participants in the study will receive bimekizumab through injections under the skin. The study will monitor participants for any side effects and assess how well the treatment works in managing the symptoms of Hidradenitis Suppurativa. Some participants may receive a placebo, which is a substance with no active medication, to compare the effects of bimekizumab. The study will also look at how the treatment affects the quality of life and skin pain experienced by participants.

The study is designed to last for several months, allowing researchers to gather information on the long-term use of bimekizumab. Participants will be regularly checked to ensure their safety and to track any changes in their condition. The results will help determine if bimekizumab is a safe and effective long-term treatment option for people with moderate to severe Hidradenitis Suppurativa.