A Study to Test Whether Spesolimab Helps People With a Skin Disease Called Netherton Syndrome

Inclusion Criteria:

• Male or female patients, aged 12 years and older (weight minimum is 35kg).

• Confirmed diagnosis of Netherton syndrome (NS) (causative SPINK5 mutations) atbaseline (Visit 2).

• At least moderate severity of erythema at baseline (visit 2) (Ichthyosis AreaSeverity Index (IASI) score ≥ 16 and IASI-Erythema (E) score ≥8) and ≥ 3 onInvestigator Global Assessment (IGA) score.

• Signed and dated written informed consent and assent in accordance withInternational Council on Harmonisation-Good Clinical Practice (ICH-GCP) and locallegislation prior to admission in the trial

• Women of childbearing potential (WOCBP) must be ready and able to use highlyeffective methods of birth control per ICH M3 (R2) that result in a low failure rateof less than 1% per year when used consistently and correctly. A list ofcontraception methods meeting these criteria is provided in the clinical trialprotocol (CTP) as well as in the patient, parent(s) (or patient's legal guardian)information.

Exclusion Criteria:

• Patients who have used topical corticosteroids (medium to high, US class I-V),topical retinoids, topical calcineurin inhibitors or keratolytics within 1 weekprior to randomisation

• Patients who have used emollient on the area to be biopsied in the previous 24 hours

• Patients who have used systemic retinoids, other systemic immunosuppressants,systemic corticosteroids or phototherapy within 4 weeks prior to randomisation

• Patients who have used systemic antibiotics within 2 weeks prior to randomisation

• Patients who have received live vaccines within 4 weeks prior to randomisation

• Patients who have received investigational products, biologics or immunoglobulinswithin 4 weeks or 5 half-lives (whichever is longer) prior to randomisation

• Severe, progressive, or uncontrolled hepatic disease, defined as >3-fold Upper Limitof Normal (ULN) elevation in Aspartate Aminotransferase (AST) or AlanineAminotransferase (ALT) or alkaline phosphatase, or >2-fold ULN elevation in totalbilirubin

• Patients who have any prior exposure to BI 655130 or another interleukin 36 receptor (IL-36R) inhibitor biologics

• Further exclusion criteria apply