Immunotherapy for the treatment of skin cancer
Melanoma is the most aggressive, and deadliest form of skin cancer. Risk factors that can contribute to its development are:
- exposure to UV radiation,
- a weakened immune system, and
- a family history of skin cancer.
Early recognition is important and is almost always curable by surgical excision. A delayed diagnosis can allow cancer to advance and spread to other, hard to treat, pigmented tissues of the body such as the eyes, bowels, and intestines.
Traditional treatments include surgery, chemotherapy, and radiation. Surgery to remove the melanoma; chemotherapy drugs to treat a local recurrence of melanoma that has spread to other areas of the body; and, radiation high-energy X-rays to kill cancer cells or stop them from growing. The drawback is that chemotherapy and radiation damage both cancerous and normal cells.
An alternative treatment is immunotherapy, which is a type of biologic therapy that uses medicines to stimulate a person’s own immune system to recognize and destroy cancer cells.
There are three types of immunotherapy currently available to treat melanoma:
- checkpoint inhibitors
- cytokine therapies
- oncolytic virus
1. Checkpoint inhibitors work by targeting signalling proteins that allow cancer cells to hide from the immune system. The three that are commonly used are:
- Ipilimumab
- pembrolizumab
- nivolumab
2. Cytokines are a family of proteins that stimulate the rapid growth and activity of the body’s immune cells. There are three cytokine therapies:
- Aldesleukin (also known as interleukin-2)
- interferon a-2b
- peginterferon a-2
3. In oncolytic virus therapy, modified versions of harmful viruses are introduced to trick the immune system into launching an attack. Specifically, T-VEC (made from a modified herpes virus) is used to treat some cases of melanoma on or under the skin or in the lymph nodes. It is injected directly into melanoma lesions or lymph nodes over several weeks or months. This treatment was approved in 2015 in the USA and Europe and is currently in clinical trials in Canada.
Despite the search for a cure and recent advances, many patients with aggressive melanoma still face an uncertain future. Consequently, there is an urgent need for further research to develop more effective treatment protocols that lead to longstanding remission.
Adapted from an article written by Muskaan Sachdeva in canadianskin.ca, summer 2018, page 9.
