A Study to Assess YH003 in Combination with Pebolizumab and Albumin Paclitaxel Injection in Subjects with Unresectable/metastatic Mucosal Melanoma

Inclusion Criteria:

• 1.Subjects must have the ability to understand and willingness to sign a writteninformed consent document.

2. Subjects must have histologically advanced or cytologically confirmedmetastatic or unresectable mucosal melanoma;

• 3.Subjects have not received standard systemic therapy; patients have diseaseprogression 6 months or more after the end of neoadjuvant or adjuvant therapy (except nab-paclitaxel), and can be enrolled in the clinical study;

4. Subject must have at least 1 unidimensional measurable disease by RECIST 1.1;

5. Subjects must be age 18 years or older;

6. Subjects must have an Eastern Cooperative Oncology Group (ECOG) performancestatus of 0 or 1.

7. Life expectancy ≥3 months based on investigator's judgement；

8. Subjects must have adequate organ function;

9. Women of childbearing potential need to have a negative pregnancy test and needto take contraceptive/contraceptive measures including their partners.

Exclusion Criteria:

• 1.Subjects have another active invasive malignancy within 5 years；

• 2.The subject has received anti-tumor therapy or other investigational drug therapyor traditional Chinese medicine (herbal medicine) with anti-tumor indications priorto the first dose;

• 3.Subjects with a history of ≥ Grade 3 immune-related adverse events resulted fromprevious immunotherapy.

• 4.History of clinically significant sensitivity or allergy ；

• 5.Primary central nervous system (CNS) malignancies or symptomatic CNS metastases.；

• 6.History of (non-infectious) pneumonitis that required corticosteroids or currentpneumonitis, or history of interstitial lung disease；

• 7.Subjects have active pulmonary embolism with hemodynamic changes 12 weeks beforethe first dose;

8. Subjects must not have a known or suspected history of autoimmune diseasewithin 3 years prior to the first dose of study treatment;

9. Subjects have clinically uncontrolled diseases;

10. Subjects have severe cardiovascular disease;

11. Subjects have evidence of active infection;

12. Subjects must not have a known or suspected history of an autoimmune disorder；

• 13.Major surgery within 4 weeks prior to study entry and Minor surgery within 2weeks prior to the first dose.

14. Any condition that the investigator assesses as inappropriate for participationin the study.