• Age \>= 18 years

• Life expectancy of three months or more

• Histologically or cytologically confirmed unresectable or metastatic stage III or IV acral melanoma that was progressed with conventional therapy

• Recommendation of subject offering archived tissue sample or previous biomarker test report. If archived tumor sample is not available, a fresh biopsy is optional, which need to be taken from needle biopsy or core needle biopsy (fine needle biopsy not allowed)

• Eastern Cooperative Oncology Group performance status (PS) ≤ 1

• At least one measurable lesion per RECIST 1.1

• Has adequate organ function defined as follows:

‣ Absolute neutrophil count ≥ 1.5 ×10\^9/L, Platelets ≥ 75× 10\^9/L and Hemoglobin ≥ 90 g/L (no blood transfusions, no platelet transfusions and no use of colony stimulating factor within 2 weeks prior to routine blood test) at screening;

⁃ Serum creatinine ≤1.5 × upper limit of normal (ULN)

⁃ Aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ≤ 2.5 ULN, AST/ALT ≤ 5 ULN for liver metastasis;

⁃ Total bilirubin ≤ 1.5 ULN

⁃ International normalized ratio (INR) ≤ 1.5 ULN, or prothrombin time (PT) ≤1.5 ULN

⁃ Activated partial thromboplastin time (APTT) ≤1.5 ULN

⁃ Serum albumin ≥30 g/L

• Willing and able to provide written Informed consent.

• Eligible male and female subjects with fertility activity or their sexual partners must use effective contraception during study period and though 90 days after last study treatment. Women of child-bearing age must have a negative serum pregnancy test within 7 days before first study treatment