The purpose of the study is to evaluate survival, response rate, safety and tolerability of YM155 given in combination with docetaxel in subjects with Stage III (unresectable) and Stage IV melanoma.

All subjects will receive YM155 and docetaxel given in a 21-day cycle. The docetaxel dose will be established based on the findings of the lead-in portion of the study (Part 1). Once the docetaxel dose is established, Part 2 enrollment will begin.

Part 1:

Part 1 is a lead-in stage that will confirm if YM155 can be safely administered in combination with docetaxel at a specified dose.

Part 2:

Subjects enrolled in Part 2 will receive YM155 and docetaxel at the dose established during Part 1.

Inclusion Criteria:

• Histologically or cytologically confirmed Stage III (unresectable) or Stage IV melanoma
• No prior systemic treatment or Cytotoxic chemotherapy for advanced melanoma (Stage III or Stage IV)
• If the subject is female, she must be non-pregnant and non-lactating at the Baseline Visit. All sexually active males and females of childbearing potential must agree to use an adequate method of contraception throughout the study period
• Eastern Cooperative Oncology Group (ECOG) performance status </= 1
• Life expectancy > 12 weeks
• At least one measurable target lesion according to Response Evaluation Criteria in Solid Tumors ({RECIST} version 1.1)
• Subjects with a previous history of non-melanoma malignancy must have undergone curative therapy for all prior malignancies and be considered disease free for at least 5 years

Exclusion Criteria:

• Major surgery within 21 days of the Baseline Visit
• Presence or history of brain metastases
• Primary ocular, choroidal or mucosal melanoma
• Known history of positive test for Hepatitis B surface Antigen (HsbAg) or Hepatitis C antibody or history of positive test for Human Immunodeficiency Virus (HIV)
• Hypersensitivity to docetaxel or polysorbate 80
• Neuropathy greater than or equal to Grade 2 at Baseline Visit
• The subject has been previously treated with YM155
• Inadequate marrow, hepatic, and/or renal functions