Tebentafusp injection is used to treat certain types of uveal melanoma (cancer of the eye) that is unable to be surgically removed or has spread to other parts of the body. Tebentafusp is in a class of medications called CD3 T cell receptor engagers. It works by stimulating the immune system to kill cancer cells.

Tebentafusp injection may cause a serious or life-threatening reaction called cytokine release syndrome (CRS). A doctor or nurse will monitor you carefully during your infusion and for at least 16 hours after your first 3 infusions and then for at least 30 minutes for all the infusions after that. Tell your doctor if you have an inflammatory disorder or if you have or think you may have any type of infection now. If you experience any of the following symptoms during and after your infusion, tell your doctor immediately: fever, chills, fast or irregular heartbeat, muscle pain, shaking, diarrhea, tiredness, weakness, difficulty breathing, shortness of breath, cough, confusion, nausea, vomiting, headache, dizziness, or lightheadedness.

Tebentafusp injection comes as a liquid and is injected intravenously (into a vein) by a doctor or nurse in a healthcare setting. It is usually injected slowly over period of 15 to 20 minutes once a week. The length of your treatment depends on how well your body responds to the medication and the side effects that you experience.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Before receiving tebentafusp injection,

• tell your doctor and pharmacist if you are allergic to tebentafusp, any other medications, or any of the ingredients in tebentafusp injection. Ask your pharmacist for a list of the ingredients.
• tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, or nutritional supplements, you are taking or plan to take. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor if you have or have ever had liver disease.
• tell your doctor if you are pregnant, or plan to become pregnant. You should not become pregnant while you are taking receiving tebentafusp injection. You will need to have a pregnancy test before you start your treatment with tebentafusp. You should use birth control to prevent pregnancy during your treatment with tebentafusp injection and for 1 week after the final dose. Talk to your doctor about birth control methods that you can use. Tebentafusp may harm your unborn baby. If you become pregnant while receiving tebentafusp injection, call your doctor.
• tell your doctor if you are breastfeeding. You should not breastfeed while you are receiving tebentafusp injection and for at least 1 week after your final dose.

Unless your doctor tells you otherwise, continue your normal diet.

Tebentafusp may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• rash
• skin redness, itching, or swelling
• lightening or darkening of the skin
• hair color changes or hair loss
• constipation
• swelling of the arms or legs
• decreased appetite
• pain in arms, legs, back, or joints
• mouth or throat pain

Some side effects can be serious. If you experience any of these symptoms or those listed in the IMPORTANT WARNING section, call your doctor immediately or get emergency medical treatment:

• pain or discomfort in right upper stomach area or yellowing of the skin or eyes

Tebentafusp may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests to check your body's response to tebentafusp injection.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.