Immunotherapy for Bile Duct Cancer

Immunotherapy is the use of medicines to help a person’s immune system better recognize and destroy cancer cells. Many types of immunotherapy are being tested in clinical trials, and some might now be used to treat bile duct cancer.

Immune checkpoint inhibitors

An important part of the immune system is its ability to keep itself from attacking the body's normal cells. To do this, it uses “checkpoint” proteins on immune cells, which act like switches that need to be turned on (or off) to start an immune response. Cancer cells sometimes use these checkpoints to avoid being attacked by the immune system.

Drugs that target these checkpoints (called immune checkpoint inhibitors) can be used to treat some bile duct cancers.

PD-1 inhibitors

Pembrolizumab (Keytruda) is a drug that targets PD-1, a checkpoint protein on immune system cells called 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.

Pembrolizumab can used along with the chemotherapy drugs gemcitabine and cisplatin to treat bile duct cancer that can’t be removed by surgery or that has spread to other parts of the body.

Pembrolizumab can also be used by itself to treat some advanced bile duct cancers, typically after other treatments have been tried, if there are no other good treatment options, and if the cancer cells have any of the following:

• A high level of microsatellite instability (MSI-H) or a defect in a mismatch repair gene (dMMR)
• A high tumor mutational burden (TMB-H), meaning the cells have many gene mutations

Tumor cells can be tested for these changes.

This drug is given as an intravenous (IV) infusion, typically once every 3 or 6 weeks.

Possible side effects

Side effects of PD-1 inhibitors can 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. These can include:

Infusion reactions: Some people might have an infusion reaction while getting this drug. This is like an allergic reaction, and can include fever, chills, flushing of the face, rash, itchy skin, feeling dizzy, wheezing, and trouble breathing. It’s important to tell your doctor or nurse right away if you have any of these symptoms while getting this drug.

Autoimmune reactions: This drug works by basically removing one of the safeguards on the body’s immune system. Sometimes this causes the immune system to attack other parts of the body, which 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 health care team right away. If you do have a serious side effect, treatment may need to be delayed or stopped, and you may be given high doses of corticosteroids to suppress your immune system.