**Study Overview:** This study is about testing a treatment called **tebentafusp** for people with advanced skin cancer, known as melanoma. The study will compare tebentafusp alone, and with another drug called pembrolizumab, to other treatments chosen by doctors. The main goal is to see how well the treatments work and if they are safe for the patients. **Key Points:** - **Duration & Visits:** This is a Phase 3 study, which means it involves many patients and could last a long time. You'll need regular visits to the study center. - **Eligibility:** You must have advanced melanoma (skin cancer) that can't be removed by surgery. You also need to have tried other treatments like anti-PD1 and anti-CTLA4 drugs before joining this study. - **Risks & Compensation:** As with any medical study, there are risks of side effects. You may or may not receive compensation for participating, and this could vary depending on the study site. **Important Terms Explained:** - **Melanoma:** A type of skin cancer. - **Anti-PD1 and Anti-CTLA4 drugs:** Medicines that help your immune system fight cancer. - **Biopsy:** A small sample of tissue taken from your body to check for cancer.