Maintenance Treatment of Toripalimab(JS001) in Patients With Unresectable Locally Advanced or Metastatic Mucosal Melanoma

Inclusion Criteria: 1. Age 18-75 years, male or female； 2. Histopathologically confirmed and diagnosed as mucosal melanoma; 3. ECOG score 0 or 1; 4. Life expectancy of at least 12 weeks； 5. SD/PR/CR after chemotherapy in combination with Endostar; 6. No contraindications, having adequate organ and marrow function； 7. Use of highly-effective contraceptive methods during the whole study for men of reproduction ability or women of childbearing potential (e.g. oral contraceptives, intrauterine contraceptive device, abstinence of sexual intercourse or barrier contraception in combination with spermatocide), and continuation of contraception for 12 months after the end of treatment； 8. The subject is voluntary to participate in the study, sign the informed consent form, with good compliance and willingness to cooperate with follow-up. Exclusion Criteria: 1. Previously treated with anti-PD-1, anti-PD-L1, anti-PD-L2; 2. Known allergy to recombinant humanized anti-PD-1 monoclonal antibody drug and its components; 3. Skin melanoma, eye melanoma, melanoma with unknown primary foci; 4. Symptomatic brain or meningeal metastases, unless the patient has been treated for \> 6 months, the imaging results are negative within 4 weeks before entering the study, and the clinical symptoms associated with the tumor are stable at the time of entering the study; 5. Female patients who are pregnant or lactating, or of childbearing potential but not using appropriate contraceptive measures; 6. Currently having serious and uncontrolled acute infection; or suppurative infection and chronic infection with prolonged wound healing; 7. Having serious heart disorder, including cardiac failure congestive, uncontrollable high-risk arrhythmia, unstable angina pectoris, infarct myocardial, severe cardiac valve disease and refractory hypertension; 8. Having neurological, mental disease or mental disorder that can not be easily controlled, poor compliance, inability to cooperate and narrate therapeutic response; 9. Patients with other malignant tumors at the same time; 10. Patients participated in other clinical trials at the same time; 11. Positive HIV; positive HCV; positive HBsAg or HBcAb whilst positive HBV DNA copies detected (limit of quantitation 500 IU/mL); 12. Active autoimmune diseases requiring systemic treatment in the past two years (e.g., use of disease-regulating drug, corticosteroid or immunosuppressant), relevant replacement therapy is allowed (e.g., thyroxine, insulin or physiological corticosteroid replacement therapy for renal or pituitary insufficiency); 13. Having received live vaccine within 4 weeks prior to the start of treatment; 14. Other severe, acute or chronic medical diseases or mental diseases or abnormalities in laboratory examination possibly increasing the relevant risk in study participation or possibly interfering the interpretation of study results as judged by the investigators.