The main purpose of this study is to evaluate the effect of LAD328 compared to placebo in participants with moderate-to-severe Hidradenitis Suppurativa (HS), and to access the safety, tolerability, pharmacokinetic and immunogenicity in participants with moderate-to-severe HS.

Hidradenitis suppurativa (HS) is a chronic skin disease of unclear etiology that affects approximately 1% of the general population.

The purpose of this study is to assess the efficacy of LAD328 compared to placebo in participants with moderate-to-severe HS.

The study participants will be randomized to one of the following treatment arms: LAD328 or Placebo.

The study includes up to 4 weeks screening period 12-week double-blind, placebo-controlled period and 8-week safety follow-up.

The total duration of study participation will be up to 20 weeks

Inclusion Criteria:

• Male or female between 18 and 65 years old inclusive.
• A diagnosis of moderate-to-severe HS defined as a total of >=5 inflammatory lesions (i.e., number of abscesses plus number of inflammatory nodules) at both the Screening and Baseline visits, with a clinical history of HS for at least 6 months.
• HS lesions present in at least 2 distinct anatomic areas (e.g., left and right axilla), one of which must be at least Hurley Stage II or Hurley Stage III at both the Screening and Baseline visits.
• History of inadequate response, or intolerance or contraindication, to a course of a systemic antibiotics for treatment of HS at the Screening visit.
• Agree to regularly use, over-the-counter topical antiseptics on their HS lesions throughout the entirety of the study.
• Participants who are woman of child-bearing potential (WOCBP) and male participants must agree to the requirements for the avoidance of pregnancy and exposure of the participant's partner to LAD328 during the trial.

Exclusion Criteria:

• HS with >20 draining tunnels either at the Screening or Baseline visits.
• Ongoing medical conditions (e.g., inflammatory bowel disease, rheumatoid arthritis, systemic lupus erythematosus and sarcoidosis) requiring systemic immunosuppressive/immunomodulating treatments (e.g., methotrexate, ciclosporin, corticosteroids, cytokine-targeted therapy and JAK inhibitors) during the trial.
• Known or suspected hypersensitivity to trial product or any of its excipients.
• Hypersensitivity or systemic reaction to a prior biologic (antibody-based) therapy (regardless of indication), that was clinically significant, as per judgment of Investigator.
• Prior treatment with LAD328.
• Live and attenuated vaccinations 4 weeks prior Pre-treatment or is planning to receive any such vaccine during the trial.
• Females who are pregnant or breast-feeding or seeking to become pregnant during the trial.