Study Objective: This research aims to test the effectiveness and safety of a treatment called tebentafusp for people with advanced melanoma (a type of skin cancer). The study compares tebentafusp alone or with another drug, pembrolizumab, against regular treatments chosen by doctors.

Key Points:

• This study is for patients who have been treated before but their cancer has worsened.
• Participants need to provide tumor samples and agree to use birth control if applicable.
• Pregnant women and those with certain health conditions (like severe heart or lung diseases) cannot join.

Eligibility: To join, you need to have a specific genetic marker (HLA-A*02:01-positive) and advanced melanoma that can't be surgically removed. You must have tried other treatments before.

Exclusions: You cannot join if you have eye melanoma, certain other cancers, untreated brain issues, or are pregnant. You should not have received certain treatments recently or have severe allergies to similar drugs.

Note: This study is important for those who need new treatment options for advanced melanoma and meet the criteria.