Evaluation of CIT-013 Efficacy in Moderate to Severe Hidradenitis Suppurativa: A Phase 2a Double-Blind, Randomized, Placebo-Controlled Trial

The primary objective is to assess the efficacy of subcutaneous CIT‑013 in participants with moderate to severe Hidradenitis Suppurativa.

Secondary objectives include:

• Characterization of safety and tolerability of CIT‑013 compared with placebo.
• Evaluation of the impact of combined and individual dosing regimens on disease activity using IHS4 and HiSCR endpoints.
• Assessment of changes in the number of draining tunnels and pain intensity.
• Measurement of health‑related quality of life changes.
• Characterization of the pharmacokinetic profile of CIT‑013.

The trial enrolled 32 participants diagnosed with Hidradenitis Suppurativa, all of whom were adults aged 18 years or older at screening and included both male and female subjects. Eligibility required a body mass index between 18 and 40 kg/m², disease duration of more than 6 months, and lesions present in at least two distinct anatomic areas with at least one area classified as Hurley Stage II or III. Additional criteria included a total count of five or more abscesses and inflammatory nodules at screening, fewer than 20 draining tunnels, and a documented inadequate response, recurrence, intolerance, or contraindication to oral antibiotics. Women of childbearing potential were required to use highly effective contraception and provide a negative pregnancy test, while fertile men with partners of childbearing potential had to use condoms and refrain from sperm donation. No specific dietary, physical activity, or other lifestyle restrictions were stipulated in the inclusion criteria.

The study is a Phase 2a, randomized, double‑blind, parallel‑arm, placebo‑controlled trial evaluating two subcutaneous dose levels of CIT‑013 (50 mg and 100 mg) versus a saline placebo in adults with moderate to severe Hidradenitis Suppurativa. Participants are screened for eligibility, provide written informed consent, and undergo baseline assessments on Day 1 when they are randomized in a 1:1:1 ratio to one of the three treatment arms. The primary efficacy assessment is the proportion of participants achieving HiSCR75 at Day 85 (Visit 11). Secondary evaluations include safety (treatment‑emergent adverse events), changes in disease activity scores (HiSCR50/90, IHS4), draining tunnel counts, pain scores, quality‑of‑life measures (DLQI, HiSQoL), and pharmacokinetic profiles. Study visits occur as follows: screening visit, baseline/randomization (Day 1), follow‑up visits on Day 29 (Visit 5), Day 43 (Visit 7), Day 85 (Visit 11), and end‑of‑study visit on Day 113 (Visit 12). Each visit includes clinical examination, lesion counts, safety labs, and patient‑reported outcomes. Overall participant involvement spans approximately 113 days from randomization, plus the initial screening period. Early termination may occur if a participant experiences a serious adverse event, meets predefined safety stopping criteria, becomes pregnant, withdraws consent, or fails to adhere to protocol‑required procedures.

The investigational product, CIT‑013, is supplied as a concentrate for solution for infusion intended for subcutaneous injection. Each dose contains 100 mg of the active substance cit‑013 and is administered by subcutaneous route according to the study dosing schedule specified in the protocol. The volume of the injection is matched to the corresponding placebo administration to maintain blinding.

The comparator used in the study is a commercially available sodium chloride 0.9 % solution in water, which serves as the placebo. The placebo is administered subcutaneously in an identical volume and appearance to the active product to preserve the double‑blind design.

Drug administration is performed by qualified study personnel under aseptic conditions. Dosing intervals and any repeat administrations follow the predefined schedule outlined in the trial protocol. Participant compliance with the injection schedule is monitored through completion of dosing logs, verification of injection site records, and periodic review of dispensing records to ensure adherence to the allocated treatment regimen.

The primary efficacy assessment is the proportion of participants achieving a ≥75% improvement in Hidradenitis Suppurativa Clinical Response (HiSCR75) in the pooled CIT‑013 dose groups (50 mg and 100 mg) compared with placebo, evaluated at visit V11 (Day 85).

Secondary efficacy evaluations include the incidence and severity of treatment‑emergent (serious) adverse events, and changes from baseline to Day 113 for several clinical and patient‑reported outcomes. These outcomes are measured using validated instruments: HiSCR50, HiSCR75, and HiSCR90 for clinical response; the International Hidradenitis Suppurativa Severity Score System (IHS4) for disease severity; a numeric rating scale (NRS) for pain; the Dermatology Life Quality Index (DLQI) and the Hidradenitis Suppurativa Quality of Life (HiSQoL) questionnaires for health‑related quality of life; and the count of draining tunnels. Assessments of draining tunnels are performed at baseline (visit V2) and at subsequent visits on Day 29 (V5), Day 43 (V7), Day 85 (V11), and Day 113 (V12). Pain, DLQI, and HiSQoL are collected at baseline and at the same scheduled visits through Day 113.

Pharmacokinetic analyses are conducted throughout the trial according to the originally assigned treatment, supporting the interpretation of efficacy outcomes.