A 52-Week Study of SYHX1901 tablet in Adults with non-segmental vitiligo.

SYHX1901 tablet is being evaluated for the treatment of non-segmental vitiligo. The study will enroll approximately 144 participants aged 18-65 with non-segmental vitiligo in 4 treatment arms. Participants will either receive study drug vs placebo oral tablets once daily (QD) for 24 weeks (Period A). In Period B (up to 52 weeks), participants who received placebo during the first 24 weeks will switch to study drug. Participants who received study drug during the first 24 weeks, will continue to receive study drug.

Inclusion Criteria:

1. Willing to sign an ICF, able to comprehend and comply with the study procedures.
2. Male or female subjects aged 18 to 65，inclusive.
3. Subjects with a clinical diagnosis of non-segmental vitiligo.
4. Agree to stop all other treatments for vitiligo during the study period.
5. Women of child-bearing potential must have a negative serum pregnancy test within 3 days prior to the first study agent administration.

Exclusion Criteria:

1. Diagnosed as other active depigmentation disease.
2. At screening or baseline visits, subject exhibits active inflammatory dermatologic disease or symptoms that in the opinion of investigators would interfere of vitiligo evaluation or response to treatment.
3. Uncontrolled thyroid function at screening as determined by the investigator.
4. Use of permanent depigmentation treatment or skin grafts.
5. Use of phototherapy, topical or systemic treatments within certain time frame prior to Day1.
6. Have active bacterial/virus/other pathogens infection or infestation that require medical intervention.
7. Have progressive or uncontrolled systemic disease, or other concomitant chronic disease that the investigators believe unsuitable to participate the study.
8. History of alcohol and drug abuse within one year prior to screening; History of neurological or mental disorders with diagnosis records, such as severe depression, suicidal tendencies, epilepsy, dementia, etc.
9. Have any other reasons determined by the investigator that the subject is not eligible for the study.