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Immunotherapy is a category of cancer treatment that helps the body’s natural immune system fight cancer. It has been called “the fourth pillar” of cancer treatment (the other three pillars being chemotherapy, surgery, and radiation therapy).
Although they are a recent development in cancer treatment, numerous immunotherapy drugs are being used to treat a variety of cancers, including skin cancers like advanced basal cell carcinoma, advanced squamous cell carcinoma, and melanomas.
Cancer and the immune system
One of the main functions of the immune system is to rid the body of anything that doesn’t belong—including harmful bacteria, viruses, and parasites, as well as damaged cells and cells that have mutated (like cancer cells). To do this, the immune system creates antibodies that attack and destroy anything abnormal.
To protect normal, healthy cells from antibodies, the body uses something called immune checkpoints. These are proteins that signal the immune system not to attack certain cells.
Some cancerous cells—including some skin cancer cells—use immune checkpoints to remain undetected. This allows the cancer to continue to grow and divide without being attacked by the immune system.
Immune checkpoint inhibitors
The immunotherapy drugs used in the treatment of skin cancer are called immune checkpoint inhibitors. These drugs work by disabling immune checkpoints, which allows the immune system to identify and attack cancerous cells.
Immune checkpoint inhibitors are typically used for advanced skin cancers, skin cancers that have spread to other sites in the body, and/or skin cancers that cannot be treated with surgery.
Different immune checkpoint inhibitors are indicated for different types of skin cancer:
- Basal cell carcinoma (BCC). Basal cell carcinoma is the most common form of skin cancer. The first immune checkpoint inhibitor indicated for the treatment of basal cell carcinoma was approved by the FDA in February 2021. It is used to treat advanced BCC that has not responded to other medications.
- Squamous cell carcinoma (SCC). Squamous cell carcinoma is the second-most common form of skin cancer. There are two immune checkpoint inhibitors that can be used in the treatment of advanced squamous cell carcinoma when surgery and/or radiation therapy are not appropriate treatment options.
- Melanoma. Melanoma is less common than the other two skin cancers on this list, but it is more likely to spread. There are four immune checkpoint inhibitors approved for the treatment of melanoma, which target different checkpoints. These are used in cases where the melanoma cannot be treated by surgery or have metastasized (spread to other sites in the body). Some are also used as adjuvant treatments—therapies that help prevent a recurrence or relapse of cancer.
- Merkel cell carcinoma. Immune checkpoint inhibitors may also be used in the treatment of this rare-but-aggressive form of skin cancer, usually when the cancer has spread.
It is important to remember that not every treatment is right for every person, and that every case of skin cancer is different. Like other cancer treatments, immunotherapy drugs cause side effects, and a person should work with their healthcare team to understand the potential risks and potential benefits before starting any treatment.
