The immune system is responsible for protecting the body from foreign substances.[1] Immunotherapy is a treatment that utilizes the body’s immune system to attack and kill cancer cells. One type of immunotherapy is cancer vaccines.[2] Vaccines can be used both to prevent and treat cancer. These vaccines function in the same way other vaccines do by introducing the body to a foreign substance (virus, bacteria, cancer, etc.) so it can build up an immune defense against it.[3]

Vaccines to prevent cancer protect against viruses that can cause cancer. These viruses include human papillomavirus (HPV) and hepatitis B virus (HBV). Infection with HPV can lead to cancer of the cervix, vagina, vulva, penis, anus, or throat. Chronic infection with HBV can increase the risk of developing liver cancer.[3]

Antigens are foreign substances that can be identified and killed by the immune system. Vaccines used to treat cancer can be made up of cancer cells, parts of cancer cells, or pure antigens from cancer cells. A patient’s immune cells may be removed and exposed to these cancer cells or antigens to create the vaccine which is then injected back into the patient. The immune system is then primed to attack cancer in the body. Because of immune system memory, these vaccines should be able to keep the immune system fighting against any cancer cells for long after they are given. These vaccines are also typically combined with other substances (called adjuvants) that can help further boost the immune system.[3]

One cancer vaccine, sipuleucel-T (brand name: Provenge), is used in the treatment of advanced prostate cancer when hormone therapy has already been tried. Side effects of this vaccine may include fever, chills, fatigue, nausea, headache, back pain, and joint pain. In rare cases, more serious side effects such as high blood pressure and difficulty breathing can occur. Another vaccine called talimogene laherparepvec (T-VEC) is used to treat advanced melanoma. T-VEC is an altered version of a herpes virus that is made to produce cytokines.[3] Cytokines are proteins that control the growth and activity of other cells including immune cells.[4] T-VEC can cause a condition known as cytokine release syndrome (CRS) leading to flu-like symptoms.[3]

References

1.     Immune System https://my.clevelandclinic.org/health/articles/21196-immune-system (accessed Jun 16, 2021).

2.     Immunotherapy https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/immunotherapy.html (accessed Jun 16, 2021).

3.     Cancer Vaccines and Their Side Effects https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/immunotherapy/cancer-vaccines.html (accessed Jun 17, 2021).

4.     Cytokines and Their Side Effects https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/immunotherapy/cytokines.html (accessed Jun 16, 2021).