Upon joining the study, the participant will be randomly assigned to one of the treatment groups. This process is double-blind, meaning neither the participant nor the researchers will know which group the participant is in.

Participants will receive either pembrolizumab or a combination of pembrolizumab and EIK1001. Both medications are administered intravenously, which means they are given through a vein.

Pembrolizumab is a medication used to treat advanced melanoma. The dosage and frequency will be determined by the study protocol.

EIK1001 is provided as a solution for injection with a concentration of 1.0 mg/mL. The specific dosage and frequency will be adjusted during the study to find the most effective dose.

Throughout the study, participants will undergo regular assessments to monitor their health and the effectiveness of the treatment. This includes imaging tests like CT or MRI scans to measure the size of the melanoma.

Participants will also have regular blood tests to check organ function and overall health.

The study aims to evaluate the response to the treatment using criteria known as RECIST 1.1. This involves determining whether the melanoma has shrunk, remained stable, or grown.

The primary goals are to assess progression-free survival, which is the time during and after treatment that the participant lives with the disease without it getting worse, and overall survival, which is the time from the start of treatment until death from any cause.

The study is expected to continue until May 2030. Participants will be followed up for a period after the last dose of the study medication to monitor long-term effects and outcomes.