• Male or female participants must be aged 18 years or over at the time, to be eligible to participate in this study.

• Histologically or cytologically confirmed metastatic UM or unresectable UM patients

• HLA-A\*02:01 positive

• Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1

• Currently undergoing first-line treatment for mUM with tebentafusp

• Tebentafusp related toxicity, including cytokine release syndrome that has resolved to grade ≤ 1 as per CTCAE v5.0.

• Male and female participants of childbearing potential who are sexually active with a non-sterilized partner must agree to use highly effective methods of birth control (eg double barrier) from the trial screening date until 6 months after the final dose of the program intervention; cessation of birth control after this point shall be discussed with a responsible physician.

• Pregnant or lactating women are prohibited from enrolling on this program.

• Male participants are not allowed to donate sperm from the time of enrolment until 6 months post- administration of program interventions.