Immune Checkpoint Inhibitors

Enhance your immune system and help you fight caner.

Immune checkpoint inhibitors are immunotherapy drugs that block immune checkpoints. These checkpoints are a part of our body’s immune system and keep immune responses from being too strong. When they are blocked, the immune cells will be able to respond more strongly to cancer.

One of the important mechanisms of our immune system is the ability to identify “foreign’ objects from normal cells, such as cancer cells or virus. This allows the immune system to attack these foreign cells without hurting normal cells in the body.

The checkpoints are proteins on immune cells, it is like switches in the immune system that need to be turned on or off to start an immune response. However, cancer sometimes takes uses this mechanism to avoid being attacked by the immune system.

Immune checkpoint inhibitors are known as monoclonal antibodies, they are designed to target these checkpoint proteins. They don’t kill cancer cells directly, but enhance the immune system to better identify and attack the cancer cells in the body.

There are different types of checkpoint proteins presented in various cancers, several immunotherapy drugs have been signed to treat these cancers, and they are given via an infusion into a vein.

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PD-1 & PD-L1 inhibitors

PD-1 is a checkpoint protein that acts as a type of “off switch” that helps keep the T cells from attacking cancer cells, when it attaches to PD-Ll, a protein on some normal (and cancer) cells. when PD-1 binds to pPDLl, it tells the T cell to leave the cancer cells alone. A large amount of PD-Ll may present on some cancer cells, and helps them hide from immune attacks.

Monoclonal antibodies that target either PD-l or PD.L1 can block this binding and boost the immune response against cancer cells.


Examples of drugs that target PD-l include:

  • Pembrolizumab (Keytruda)
  • Nivolumab (Opdivo)
  • Cemiplimab (Libtayo)


Examples of drugs that target PD-Ll include.

  • Atezolizumab (Tecentrig)
  • Avelumab (Bavencio)
  • Durvalumab (Imfinzi)

Both PD-l and PD-Ll inhibitors have been shown to be helpful in treating different types of cancer.

CTLA-4 inhibitors

CTLA-4 is another checkpoint protein on some T cells that acts as a type of “offs witch” to help keep the immune system in check.

lpilimumab (Yervoy) is a monoclonal antibody that attaches to CTLA-4 and stops it from working. This can help boost the body’s immune response against cancer cells.

This drug is typically used along with a PD-1 inhibitor, such as nivolumab. it can be used to treat melanoma of the skin and several other types of cancer.

LAG-3 inhibitors

LAG-3 is a checkpoint protein on some types of immune cells that normally acts as a type of “off switch” to help keep the immune system in check.

Relatlimab is a monoclonal antibody that attaches to LAG-3 and stops it from working. This can help boost the body’s immune response against cancer cells

This drug is given along with the PD-l inhibitor nivolumab (in a combination known as Opdualag). it can be used to treat melanoma of the skin, and it’s being studied for use in several other types of cancer.

Bispecific Antibody

There are immunotherapy drugs that are designed to target two different checkpoint proteins. An example is Cadonilimab, it is a PD-1/CTLA-4 bispecific antibody for the treatment of solid cancers, including cervical cancer, lung cancer, gastric/gastroesophageal junction cancer, oesophageal squamous cell cancer, liver cancer and nasopharyngeal cancer.

Side Effects

Some of the more common side effects of checkpoint inhibitors include:

  • Diarrhea
  • Fatigue
  • Cough
  • Nausea
  • Skin rash
  • Poor appetite
  • Constipation
  • Muscle and joint pain

Other more serious side effects occur less often:

Infusion reactions: some people might have an infusion reaction while getting 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. It’s important to tell your doctor or nurse right away if you have any of these symptoms while getting one of these drugs.

Autoimmune reactions: By targeting a checkpoint protein, these drugs remove one of the safeguards on the body’s immune system. Sometimes the immune system responds by attacking other parts of the body, which can cause serious or even life-threatening problems in the lungs, intestines, liver, hormone-making glands, kidneys, or other organs.

It’s very important to report any new side effects to someone on your health care team as soon as possible. f serious side effects do occur treatment may need to be stopped and you might be given high doses of corticosteroids to suppress your immune system.