Inclusion Criteria:
1. Able to understand and willing to sign written informed consent.
2. Age ≥18 years at consent; any sex.
3. Clinical diagnosis of nonsegmental vitiligo, with all of the following at screening and baseline: T-BSA ≥5%; T-VASI ≥4; F-BSA ≥0.5%; F-VASI ≥0.5%; and Considered suitable for systemic therapy by the investigator.Note: When assessing body surface area (BSA) and the Vitiligo Area Scoring Index (VASI), a Wood's lamp must be used in a darkroom. 4. Agrees to discontinue all vitiligo treatments from screening through the last safety follow-up visit.
5\. Agree to adopt effective contraceptive measures and meet the following requirements:
1. Men with fertility potential: use highly effective contraception within at least 90 days from screening to the last dose of medication; do not donate sperm.
2. Women with fertility potential (WOCBP): negative serum pregnancy test at screening, and negative urine pregnancy test prior to the first dose; use highly effective contraception within at least 90 days from screening to the last dose of medication; do not donate oocytes.
3. Women without fertility potential (as defined in Appendix A) are exempt from the above restrictions.
6\. Willing and able to comply with study procedures, including standardized lesion photography.
Exclusion Criteria:
1. Patients clinically diagnosed with other types of vitiligo (e.g., segmental vitiligo) or other hypopigmentary skin disorders (including but not limited to piebaldism, pityriasis alba, leprosy, post-inflammatory hypopigmentation, progressive patchy hypopigmentation, nevus anemicus, chemical leukoderma, and pityriasis versicolor).
2. Following screening evaluation, white hair appears on more than 33% of the facial body surface area affected by vitiligo lesions; or white hair appears on more than 33% of the total body surface area (including the face) affected by vitiligo lesions.
3. Spontaneous and pronounced repigmentation occurring within the 6 months prior to screening (e.g., evident repigmentation without any prior treatment, as determined by the investigator).
4. Current or prior use of decolorizing agents such as hydroquinone monobenzyl ether (including Benoquin® \[Monohydroquinone\]).
5. History of melanocyte-keratinocyte transplantation or other surgical treatments for vitiligo.
6. The subject had used laser therapy or phototherapy (including tanning beds) within the 8 weeks preceding the first dose.
7. The subject had used dihydroxyacetone (commonly found in tanning products) within the 4 weeks preceding the first dose.
8. The subject had poorly controlled thyroid disease as assessed by the investigator and/or a specialist, or exhibited clinically significant abnormalities in thyroid-stimulating hormone (TSH) or free T3 and free T4 during screening, indicating active thyroid dysfunction.
9. The subject was pregnant or breastfeeding, or had plans to become pregnant during the study period.
10. The following concomitant diseases or past medical history are present:
1. current or past history of thrombocytopenia, coagulopathy, or platelet dysfunction; or current use of anticoagulants or medications known to induce thrombocytopenia.
2. History of venous thrombosis or arterial embolism, including but not limited to deep vein thrombosis, pulmonary embolism, moderate to severe heart failure \[NYHA class III or IV\], cerebrovascular accident within 6 months prior to screening, myocardial infarction, coronary stent implantation, or coronary artery bypass grafting \[CABG\].
3. Diagnosis of other serious cardiovascular diseases, including but not limited to angina pectoris, peripheral arterial disease, or uncontrolled arrhythmias such as atrial fibrillation, supraventricular tachycardia, ventricular tachycardia, or various forms of myocarditis.
4. Uncontrolled hypertension (as assessed by the investigator).
5. Disabled patients requiring bed rest or wheelchair use.
6. Patients who have undergone organ transplantation.
7. Presence of any malignant tumor or history of malignant tumor (excluding well-treated cases such as basal cell carcinoma or squamous cell carcinoma of the skin).
8. Conditions that may interfere with drug absorption, including but not limited to short bowel syndrome.
9. Chronic or recurrent infectious diseases, including but not limited to chronic renal infections, chronic thoracic infections (e.g., bronchiectasis), recurrent urinary tract infections (recurrent pyelonephritis or chronic persistent cystitis), fungal infections, prior history of prosthetic joint infection, or open, exudative, or infected skin wounds or ulcers. Current or past history of disseminated herpes zoster, or recurrent herpes zoster (with more than one episode).
10. Current or past history of disseminated herpes simplex.
11. Having received systemic anti-infective therapy within 4 weeks prior to the first dose, or having any active infection judged by the investigator to be unsuitable for participation in this study.
12. Albinism.
13. Any other clinically significant disease, other than vitiligo, judged by the investigator to be unsuitable for participation in this clinical study.
11. During screening, the 12-lead electrocardiogram should demonstrate clinically significant abnormalities requiring treatment (e.g., acute myocardial infarction, severe tachyarrhythmias or bradyarrhythmias), or indicate the presence of serious underlying cardiac disease (e.g., cardiomyopathy, severe congenital heart disease, diffuse low voltage in all leads, Wolff-Parkinson-White syndrome), or show a QTc interval\>480 ms.
12. The subject must have experienced severe trauma or major surgery within 30 days prior to the screening visit, as judged by the investigator.
13. The subject must also have a history of clinically significant drug or alcohol abuse within the 6 months preceding the screening visit, as judged by the investigator.
14. The subject must have a history of failed treatment with any systemic or topical JAK inhibitor for vitiligo or other inflammatory diseases.
15. The washout period prior to the first dose must meet one of the following criteria:
1. For any investigational or experimental therapy, \<12 weeks or 5 half-lives (if known), whichever is longer;
2. For immunomodulatory biologics, \<12 weeks or 5 half-lives (if known), whichever is longer;
3. For live vaccines, \<8 weeks, or if the subject is scheduled to receive a live vaccine during the study period or within 8 weeks after the last dose of the study drug.
4. Systemic immunosuppressive or immunomodulatory small-molecule agents (e.g., corticosteroids \[oral or intravenous\], methotrexate, cyclosporine, dapsone, azathioprine, etc.) must have been discontinued for \<4 weeks.
Note: The use of inhaled or nasal corticosteroids is permitted. Note: For non-cutaneous conditions (e.g., exacerbation of asthma, bronchitis), if judged acceptable by the investigator and the sponsor (or their designated personnel), prednisone-equivalent doses ≤10 mg/day may be used for ≤7 consecutive days.
5. For any topical or systemic JAK inhibitor: \<4 weeks.
6. For traditional Chinese medicines/proprietary Chinese medicines used in the treatment of vitiligo: \<4 weeks.
7. For any topical treatment of vitiligo other than JAK inhibitors: \<2 weeks.
8. For any oral or topical PDE4 inhibitor (e.g., apremilast, criborol): \<1 week.
9. For potent systemic CYP3A4 inhibitors and potent systemic CYP3A4 inducers: \<1 week or 5 half-lives (if known), whichever is longer. Examples include, but are not limited to: fluconazole, itraconazole, carbamazepine, ritonavir, St. John's wort, grapefruit/grapefruit juice.
16. During screening visits, any of the following abnormal laboratory test results shall be considered:
1. serum aspartate aminotransferase (AST)\> 2×ULN;
2. serum alanine aminotransferase (ALT)\> 2×ULN;
3. total bilirubin (TBIL) ≥ 1.5×ULN (trial participants with a history of Gilbert syndrome who have TBIL ≥ 1.5×ULN but direct bilirubin (DBIL) ≤ ULN shall not be excluded based on this criterion);
4. absolute neutrophil count (ANC) \<1.5×10⁹/L;
5. platelet count (PLT) \<90×10⁹/L;
6. hemoglobin (HGB) \<90 g/L;
7. other laboratory abnormalities that are clinically significant and judged by the investigators to render the participant unsuitable for enrollment.
Note: If a laboratory test result exceeds the threshold specified in the protocol but is suspected to be transient (e.g., due to physiological factors or assay variability), or only marginally exceeds the threshold, the test may be repeated once during the screening period (only once is permitted) to clarify the result. If the repeat test still exceeds the threshold, the trial participant shall be excluded from screening.
17. Evidence of Mycobacterium tuberculosis infection (i.e., tuberculosis) is present.
18. A positive anti-HIV antibody test result is present.
19. Evidence of active hepatitis B virus (HBV) or hepatitis C virus (HCV) infection, or risk of HBV or HCV relapse, is present.
20. The participant has a known hypersensitivity to povotuxin phosphate or to any excipient contained in povotuxin phosphate tablets.
21. Any condition-as judged by the investigator-that could compromise the participant's full participation in the study (including administration of the study medication and attendance at scheduled study visits), pose a significant risk to the participant, or interfere with the interpretation of study data, laboratory results, or screening assessment outcomes.
