Immunotherapy for Thymus Cancer

Your immune system has built-in safeguards to keep it from attacking healthy cells. One way it does this is through “checkpoint” proteins on immune cells. These act like on and off switches to start an immune response. Cancer cells sometimes use these checkpoints to avoid being attacked by the immune system.

Drugs that target these checkpoints are called immune checkpoint inhibitors. They can be used to treat some thymus cancers, usually thymic carcinoma. Current research studies are testing immunotherapy combinations with chemotherapy and targeted therapies.

How do checkpoint inhibitors help treat thymus cancer?

Pembrolizumab (Keytruda) is a drug that targets PD-1, a protein on T cells. PD-1 normally helps keep T cells from attacking other cells in the body (including some cancer cells). By blocking PD-1, this drug boosts the immune response against cancer cells. This can shrink some tumors or slow their growth.

Atezolizumab (Tecentriq) and avelumab (Bavencio) are drugs that target PD-L1, a protein related to PD-1 that is found on some tumor cells and immune cells. Blocking this protein can help boost the immune response against cancer cells. This can shrink some tumors or slow their growth.

For thymus cancers, these drugs are used mainly for thymic carcinoma. They’re usually used after chemotherapy has stopped working. They are used much less often for thymoma, because of a higher risk of triggering acute autoimmune conditions, such as myasthenia gravis flares.

How are immunotherapy drugs given?

Pembrolizumab, atezolizumab, and avelumab are usually given as an infusion into a vein (IV). However, some immunotherapies may now be given as an injection under the skin. Treatment is given on a schedule of cycles, usually every 2 to 4 weeks depending on the specific drug, for as long as it continues to help.

Is immunotherapy a treatment for thymoma?

Thymoma is unique when it comes to immunotherapy. The thymus is part of the immune system. One of its jobs is to keep the body from attacking itself. Because of this, people with thymoma have a much higher risk of serious side effects from checkpoint inhibitors than people with most other cancers.

These immune-related side effects can include:

• Severe muscle or nerve problems
• Inflammation of the heart muscle (myocarditis), which can be life-threatening

Because of this risk, checkpoint inhibitors are generally not recommended for thymoma. They are mainly considered an option for thymic carcinoma instead. If a checkpoint inhibitor is used for thymoma, it's typically only in a clinical trial setting with very close monitoring.

What are side effects of immunotherapy?

Possible side effects of checkpoint inhibitors include:

• Feeling tired or weak
• Fever
• Cough
• Nausea
• Itching
• Skin rash
• Loss of appetite
• Muscle or joint pain
• Shortness of breath
• Constipation or diarrhea

Other, more serious side effects occur less often.

Infusion reactions: Some people might have an infusion reaction while getting one of these drugs. This is like an allergic reaction, and can include fever, chills, flushing of the face, rash, itchy skin, feeling dizzy, wheezing, and trouble breathing.

Tell your doctor or nurse right away if you have any of these symptoms while getting one of these drugs.

Autoimmune reactions: These drugs work by removing one of the safeguards on the body’s immune system. Sometimes this causes the immune system to attack other parts of the body. This can cause serious or even life-threatening problems in the lungs, intestines, liver, hormone-making glands, kidneys, skin, or other organs.

It’s very important to report any new side effects to your healthcare team right away. If you do have a serious side effect, treatment may need to be stopped and you may be given high doses of corticosteroids to suppress your immune system.

More information about immunotherapy

To learn more about how drugs that work on the immune system are used to treat cancer, see Cancer Immunotherapy.

To learn about some of the side effects listed here and how to manage them, see Managing Cancer-related Side Effects.