Randomised, Double-blind, Placebo-controlled, Phase IIb/Phase III Study to Evaluate the Efficacy and Safety of Spesolimab in Patients With Moderate to Severe Hidradenitis Suppurativa. Lunsayil 1.

Inclusion Criteria:

1. Of full age of consent at screening.

2. Signed and dated written informed consent in accordance with International Council on Harmonisation-Good clinical practice (ICH-GCP) and local legislation prior to admission to the trial.

3. Moderate to severe HS.

4. HS lesions in at least 2 distinct anatomic areas.

5. Biologic naive or Tumor Necrosis Factor inhibitor (TNFi)-exposed for HS.

6. For biologic naïve, inadequate response to an adequate course of appropriate oral antibiotics for treatment of HS in the last 1 year prior to the Baseline visit, as per investigator discretion. All participants must have previous exposure to antibiotics for HS.

7. Total AN count of greater than or equal to 5.

8. Total dT count of at least 1 at Baseline visit. Further inclusion criteria apply.

Exclusion Criteria:

1. Participants who must or wish to continue the intake of restricted medications or any drug considered likely to interfere with the safe conduct of the trial.

2. Prior exposure to any immunosuppressive/immunomodulatory biologic other than TNFi for HS.

3. Prior exposure to Interleukin 36 receptor (IL-36R) inhibitors including spesolimab.

4. Treated with any investigational device or investigational drug of chemical or biologic nature within a minimum of 30 days or 5 half-lives of the drug, whichever is longer.

5. Women who are pregnant, nursing, or who plan to become pregnant while in the trial.

6. Participants with history of allergy/hypersensitivity to the systemically administered trial medication agent or its excipients.

7. Participants with a transplanted organ (with exception of a corneal transplant \>12 weeks prior to screening) or who has ever received stem cell therapy (e.g., Remestemcel-L).

8. Participants with any documented active or suspected malignancy or history of malignancy within 5 years prior to the screening visit, except appropriately treated basal cell carcinoma of the skin, squamous cell carcinoma of the skin, or in situ carcinoma of uterine cervix.

Further exclusion criteria apply.