Reviewed by: HU Medical Review Board | Last reviewed: June 2023

Your immune system is your body's defense against cells that are not normal. These cells could be infected with a virus or bacteria, or they could be abnormal cells that are dividing rapidly and uncontrollably, which can lead to cancer.1

It may be possible to treat skin cancer by turning your immune system against it. Several medicines are available that:2

  • Help your immune system identify cancer cells
  • Boost your immune system
  • Create an immune response to the tumor

Immune system basics

The immune system is a network of cells and proteins that helps your body fight germs. Two main parts of the immune system include the innate and adaptive immune systems.1

The innate immune system is like your body's first line of defense. It works by recognizing germs that are not normally found in your body. When it finds a germ, it sends out signals to other parts of the immune system to attack it.1

The adaptive immune system is like your body's special forces. It learns to recognize specific germs and how to fight them. This means that if you are ever exposed to the same germ again, your body can fight it off more quickly and easily.1

B-cells and T-cells are the main cells in the adaptive immune system. They recognize invaders by the antigens on their surfaces. Antigens are molecules that trigger an immune response. When a B-cell or T-cell recognizes an antigen, it becomes activated.1

B-cells make antibodies that stick to antigens and help the immune system fight off invaders. T-cells kill infected cells and recruit other immune cells to help fight the infection.1

T-cells are important targets for drugs called immune checkpoint inhibitors. These drugs block the signals that T-cells need to become activated. This can help the immune system fight cancer cells or other diseases.1

What are immune checkpoint inhibitors?

Immune checkpoint inhibitors block the interaction between T-cells and cancer cells, allowing the immune system to function against cancer.3

These drugs do not kill cancer cells directly, but they help the immune system do a better job of killing them.3

There are different checkpoint proteins that checkpoint inhibitors can target. They are also known as targeted therapy. Drugs that target other checkpoint proteins are now used to treat some types of cancer. These drugs are given as an infusion into a vein (IV). These include:3

  • Keytruda® (pembrolizumab)
  • Opdivo® (nivolumab)
  • Libtayo® (cemiplimab)
  • Tecentriq® (atezolizumab)
  • Bavencio® (avelumab)
  • Imfinzi® (durvalumab)
  • Yervoy® (Ipilimumab)
  • Imjuno® (tremelimumab)
  • Opdualag® (nivolumab and relatlimab-rmbw)

What do immune checkpoint inhibitors treat?

Immune checkpoint inhibitors treat a variety of cancers, including:3

What are cytokines?

Immune cells talk with each other by sending signals. These signals are called cytokines. Cytokines are proteins that stick to receptors on the surface of immune cells. When a cytokine sticks to a receptor, it activates the receptor. This activation causes changes inside the cell.4

You can think of receptors and ligands like a lock and key. The receptor is like the lock, and the ligand is like the key. When the ligand fits into the receptor, it activates the receptor.4

Cytokines are essential for immune cell communication because they help cells to talk to each other. They also have a role in cell growth and immune cell activation.4

Unlike targeted therapies, cytokines are general immune system boosters. They help the immune system fight cancer cells by rallying its defenses.4

Two cytokines used to treat skin cancer are:4

  • Interleukin-2
  • Interferon (interferon-alfa and peginterferon)

What do cytokines treat?

Cytokines treat a variety of cancers, including:4

  • Melanoma
  • Metastatic or advanced CSCC

What is intralesional immunotherapy?

Talimogene laherparepvec is an oncolytic virus that shrinks melanoma tumors. The exact way it works is not well known. It is thought to work by:5

  • Killing tumor cells by causing them to burst open
  • Creating an immune response

The Bacillus Calmette-Guerin (BCG) vaccine has been used to treat stage III or recurrent melanoma for many years. Its use has become less common now that new immunotherapies are available.5

This vaccine works by introducing a weakened strain of bacteria into the body. The immune system then attacks the bacteria, and in the process, it also attacks nearby cancer cells.5

Can immunotherapies be used together?

It may be possible to combine immunotherapies and target the cancer in different ways. Researchers continue to study if more combinations of immunotherapy might help improve treatment.3

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