Study of the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of ICP-538 in Healthy Subjects

Inclusion Criteria: 1. Voluntarily sign the ICF.. 2. BMI between 18-26 kg/m² (inclusive). Male weight ≥50 kg; female weight ≥45 kg. 3. Vital signs, physical examination, ECG, Chest X-ray, Abdominal ultrasound results at screening are within normal range or showing minor deviations deemed not clinically significant by the investigator. 4. Laboratory test results at screening and baseline are within the normal reference range. 5. Reproductive Status：Females of non-childbearing potential . Male participants and their partners must agree to use effective contraception throughout the study and for 3 months after the last dose. Male participants must not donate sperm during this period. Exclusion Criteria: 1. Evidence or history of clinically significant diseases, or Evidence or history of allergic diseases . 2. Clinically significant gastrointestinal dysfunction that may affect drug intake, transport, or absorption. 3. Acute illness within 14 days before dosing. 4. Severe infection within 6 months before dosing, or chronic/recurrent infections. 5. Participant and/or first-degree relative with hereditary immunodeficiency. 6. Major trauma or surgery within 3 months before dosing. 7. History of active/latent TB or contact with an open TB case within 6 months before dosing. 8. Positive urine drug screen. 9. Alcohol abuse. 10. Use of tobacco/nicotine products within 3 months before the first dose. 11. Use of any prescription/non-prescription drugs, herbal medicines, supplements within 14 days before first dose; or systemic corticosteroids, immunosuppressants/modulators, hormone replacement therapy within 30 days before first dose; or any other factor affecting drug absorption, distribution, metabolism, and excretion. 12. Consumption of caffeine-containing foods/beverages within 48 hours before the first dose. 13. Use of known CYP3A4 inducers/inhibitors within 14 days or 5 half-lives (whichever is longer) before the first dose. 14. Dieting, dietary therapy within 30 days before the first dose. 15. Positive for syphilis antibody, HCV-Ab, HBsAg, HBcAb, or HIV-Ab at screening. 16. Administration of live vaccines within 6 weeks before the first dose or planned during study or within 8 weeks after study.