The main purpose of this study is to assess the efficacy of multiple dosing regimens of LAD191 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.

The purpose of this study is to assess the multiple dosing regimens of LAD191 compared to placebo in participants with moderate-to-severe Hidradenitis Suppurativa (HS). The study has a prospectively defined adaptive design that will utilize interim data for futility evaluation.

The study includes up to 4 weeks screening period 16-week double-blind, placebo-controlled period (Treatment period 1), 16-weeks LAD191 double-blind period (Treatment period 2), and 12-week safety follow-up.

The study participants will be randomized to one of the following treatment arms: LAD191 dose A, LAD191 dose B; LAD191 dose C, Adalimumab or Placebo.

Inclusion Criteria:

• Aged greater than or equal to (>=) 18 to less than or equal to (<=) 65 years.
• 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/Day 1 visits, with signs and symptoms 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/Day 1 visits.
• History of inadequate response, intolerance, or contraindication to a course of a systemic antibiotics for treatment of HS at the screening visit.
• Regular use of over-the-counter topical antiseptics on HS lesions and agrees to regular use, throughout the entirety of the study.
• Participants who are women of child-bearing potential (WOBCP) and male participants must agree to the requirements for the avoidance of pregnancy and exposure of the participant's partner to LAD191 during the study.

Exclusion Criteria:

• HS with >20 draining tunnels at the Screening or Baseline/Day 1 visit.
• Ongoing medical conditions requiring systemic immunosuppressive/immunomodulating treatments during the study.
• Known hypersensitivity to LAD191 or any of its excipients.
• Known hypersensitivity to adalimumab or biosimilar or any of its excipients or meeting any warning or contraindication to adalimumab treatment as per the approved product information, and as per the Investigator's judgment.
• Hypersensitivity or systemic reaction to a prior biologic (antibody-based) therapy, regardless of indication, that was clinically significant, as per the Investigator's judgment.
• Prior treatment with LAD191.
• Live or attenuated vaccinations 4 weeks prior to Baseline/Day 1 or is planning to receive any such vaccine during the study.
• Pregnant or breastfeeding women, or women planning to become pregnant or breastfeed during the study.
• Intention to use any concomitant medication or therapy that is not permitted by this protocol or failure to meet the required washout period for a particular prohibited medication prior to Baseline/Day 1.