Melanoma
Stages III and IV: Immunotherapy
Once the cancer has spread to many parts of the body, surgical treatments are rendered ineffective. There are several lines of treatment that doctors generally use at this stage. One method is to use drugs which stimulate the patient’s immune system to fight the tumor. One of these drugs, called Yervoy or ipilimumab, attacks CTLA-4. CTLs (Cytotoxic T lymphocytes) are cells designed to kills cancer cells. CTLA-4 regulates CTLs and the number of cancer cells they kill, so targeting it with ipilimumab increases the effectiveness of the immune system by giving CTLs free reign.
Another immune system related drug is Keytruda or MK-3475. This drug was designed to be used after ipilimumab and targets PD-1, a sensor on the surface of the patients T cells that suppresses immune response when activated. Similarly to CTLA-4, when PD-1 is compromised the patient’s immune system reacts more effectively.
Of course, there is a reason that CTLA-4 and PD-1 existed in the first place. Without them there is a chance that a patient’s immune system will get out of control and start attacking non-cancerous cells. Side effects of Yervoy and Keytruda therefore include damage to healthy organs and tissues by uncontrolled T cells.
The second method of immunotherapy boosts the patient’s immune system by adding to it rather than stimulating it. Interferon-alfa is a small protein that immune cells commonly produce to fight viruses and cancers. Instead of causing the immune system to produce interferon-alfa, doctors have developed it in the lab and can now inject the protein into melanoma patients to fight of the cancer. Interleukin-2 is another naturally occurring element of the immune system, and can also be used in this way to fight the later stages of melanoma.
Ipillimumab helps promote T cell activation by blocking the supressive effects of the CTLA-4 receptor.
