This study is a Phase Ic/II clinical trial conducted in Chinese patients with moderate-to-severe hidradenitis suppurativa (HS), aiming to evaluate the safety and efficacy of LT-002-158 tablets in the treatment of moderate-to-severe HS.

The study consists of two parts. The Phase Ic portion employs an open-label, single-arm design to primarily investigate the safety and tolerability of LT-002-158 tablets in patients with moderate-to-severe HS. The Phase II study adopts a randomized, double-blind, placebo-controlled, parallel-group design, with an open-label, single-arm extension phase, to primarily assess the therapeutic efficacy of LT-002-158 tablets in patients with moderate-to-severe HS.

Inclusion Criteria:

1. Male or female aged 18 to 75 years (inclusive), with body mass index (BMI) between 17.5 and 40.0 kg/m² (inclusive) and body weight ≥45.0 kg;
2. Diagnosis of hidradenitis suppurativa (HS) with disease duration of at least 6 months prior to enrollment;
3. Have inadequate response or intolerance to prior HS treatments and are suitable candidates for this study on investigator's judgment;
4. Total count of abscesses and inflammatory nodules ≥4 at baseline;
5. No pregnancy plans during the study and for 6 months after the last dose, with agreement to use effective contraception methods;
6. Understand and voluntarily sign the informed consent form; Willing and able to to complete patient diary entries as required by the protocol;
7. The subject is willing and able to comply with all protocol requirements by investigator's judgment.

Exclusion Criteria:

1. Presence of >20 fistulas or deeply extensive coalescing lesions;

2. Other significant dermatological conditions that may interfere with efficacy evaluation or require concomitant treatment (e.g., seborrheic dermatitis), or any skin conditions deemed by investigators as potentially affecting study assessments (e.g., tattoos, scars);

3. Any of the following comorbidities:

   1. Active tuberculosis;
   2. Active hepatitis B/C, syphilis, or human immunodeficiency virus (HIV) infection;
   3. Severe cardiovascular diseases including: Congestive heart failure (NYHA class ≥II); Angina pectoris >grade 1; Known structural heart disease; Major cardiovascular events within screening period (myocardial infarction, unstable angina, acute coronary syndrome, stroke or transient ischemic attack, etc.); Ventricular fibrillation; TDP; atrial fibrillation; Unexplained syncope of non-cardiac origin;
   4. Immunodeficiency or immune-related disorders (organ/bone marrow transplantation, splenectomy, IgG4-related disease, vasculitis, etc.) or active autoimmune diseases requiring treatment (psoriasis, atopic dermatitis, rheumatoid arthritis, etc.);
   5. History or symptoms of malignancy in any organ system within 5 years prior to screening, regardless of treatment status or evidence of recurrence/metastasis (except appropriately treated non-metastatic cutaneous carcinoma in situ or cervical basal/squamous cell carcinoma in situ);
   6. Gastrointestinal disorders or surgeries (gastrectomy, gastric bypass, etc.) that may affect oral drug absorption;

4. Family history of sudden death or long QT syndrome, or personal history of congenital/medication-induced long QT syndrome;

5. Any of the following laboratory abnormalities:

   1. Estimated glomerular filtration rate (eGFR) or creatinine clearance (CrCl) <60 mL/min/1.73m²;
   2. Total bilirubin ≥1.5×upper limit of normal (ULN);
   3. ALT ≥1.5×ULN or AST ≥1.5×ULN;
   4. Hemoglobin <9.0 g/dL, WBC <3.0×10⁹/L, neutrophils <1.5×10⁹/L, lymphocytes <0.75×10⁹/L, platelets <100×10⁹/L;
   5. Serum potassium, magnesium, or calcium below lower limit of normal;
   6. QTcF >450 ms or QRS >110 ms on screening ECG;
   7. Blood pressure ≥150/90 mmHg despite antihypertensive treatment;

6. Use of adalimumab or other biologics within 8 weeks or 5 half-lives prior to first dose (whichever longer) (≤20% of enrolled subjects may have prior biologic exposure without treatment failure);

7. Systemic antibiotic therapy within 2 weeks or systemic retinoid therapy within 4 weeks prior to first dose.