AVTX-009 will be administered as a subcutaneous injection every 2 weeks.

Matching placebo will be administered as a subcutaneous injection every 2 weeks.

IHS4 score is calculated by the number of nodules (multiplied by 1) plus the number of abscesses (multiplied by 2) plus the number of draining tunnels (multiplied by 4). A total score of 3 or less signifies mild disease, 4 to 10 signifies moderate disease, and 11 or higher signifies severe disease.

An abscess is a circumscribed collection of purulent exudates frequently associated with swelling, erythema, and other signs of inflammation, such as fluctuance, tenderness, and pain. An inflammatory nodule is a raised, deep-seated, three-dimensional, round nodule, greater than 10 mm in diameter. It is tender and erythematous without evidence of fluctuance.

Draining fistula is defined as a pathologic passageway connecting to the skin surface from dermis or subcutaneous tissue that drains serous or purulent fluid, either spontaneously or by gentle palpation.

The skin pain NRS is a single-item measure to capture the patient's self-reported skin pain severity by rating the worst level of skin pain in the last 24 hours as a number on a numerical rating scale from 0 (no pain) to 10 (worst pain imaginable).

The number of patients with flares will be programmatically calculated based on the assessed lesion counts. A flare is defined as ≥ 25% increase in AN count plus an increase of ≥ 2 in AN count compared to Baseline.

The incidence of patients with AVTX-009 anti-drug antibodies (ADA).

Incidence of adverse events (AEs).