Additional Study Information: This is a Phase I study of a weekly intra-patient escalation dose regimen with IMCgp100 in patients with metastatic uveal melanoma (mUM). To help decide whether or not patients can take part in a research study looking at a new form of treatment for advanced uveal melanoma, their blood need to first be tested to determine their Human Leukocyte Antigen (HLA) type. To be able to take part in the research study, patients need to be HLA type A2 positive. The sponsor believes that this type of cancer is more likely to respond to this new type of treatment if they are also HLA type A2 positive. The study doctor does not know the patients' HLA type so he/she will need to do a blood test to find out. About half of the general population are HLA type A2 positive.