What Is a Vaccine Against Cancer, Anyway?

Recent news of a vaccine against breast cancer being tested successfully in a patient in Florida has been shared widely on social media and news outlets as some sort of a breakthrough. While vaccines against cancer are not a new thing, and other cancer vaccines — some for species other than humans — are in development, it has been a while since such a vaccine has received this much coverage. So let’s break it down and see what is going on here…

According to the National Cancer Institute, cancer vaccines are a kind of biological therapy. This means that diseases are treated using living organisms or “substances derived from living organisms, or laboratory-produced versions of such substances.” In this case, the person with cancer is the living organism, and the person’s own immune system is the substance(s) derived from such an organism. Without going too much into detail, there are some things you need to know about cancer and its relationship to the immune system:

  1. Cells in our body multiply at different rates. Skin cells, for example, multiply quickly. This is why your skin regenerates fairly quickly after a scrape or a burn. Other cells, like those in our bones, take longer to multiply and heal an injury. Each time a cell multiplies, mechanisms in the cells make sure that the genetic information is accurately transcribed from one cell to the new cells being made. An error at that stage may trigger what is called an “oncogene,” which is a gene that makes the cell multiply without any kind of control, creating a cancer.
  2. Environmental exposures, such as UV light or chemical carcinogens, can also have this effect on cells.
  3. Chronic irritation from viral infections such as Human Papillomavirus or Hepatitis B can also make cells make errors in how their genes are copied during cell division.
  4. The therapy used for a cancer depends on the type of cells that make up the cancerous tissue. Not all cancers are the same, so when we say that cancer is a disease, we are really talking about different diseases all having in common the trait that cells have gone out of control in their reproduction.
  5. The immune system usually detects these abnormally-reproducing cells and takes them out. However, there are circumstances under which the cancerous cells may not be detected by the immune system, such as when the cancerous cells look “normal” to the immune system because the proteins and sugars on their surface (also known as antigens) are normal, or when the cancerous cells are completely surrounded by normal cells.
  6. There are different ways in which the immune system can take out those cancerous cells. One way is to have immune cells release chemicals that destroy the cells directly, or they release chemicals that call on other cells to mechanically destroy the cells by basically “eating” the cancerous cells. Another way is to create antibodies that attach to the antigens on cancerous cells and mark them for removal by other specialized cells.

If that last step sounds familiar, it is because that is pretty much how vaccines against viruses and bacteria work. You present antigens to the immune system without causing disease. The immune system them makes antibodies that circulate until they encounter the real thing. The antibodies then coat the invading viruses or bacteria and mark them for destruction before they are able to cause disease.

In the case in Florida, the patient still had to undergo a mastectomy to make sure that the cancer was removed in case the vaccine didn’t work. However, the researchers claim that they are having successes with the vaccine that could lead to a viable vaccine in less than ten years. Their vaccine, it seems, is telling the immune system that the antigens on these types of cancer cells are to be marked by antibodies and the cells destroyed. While the patient had an early form of the cancer, the researchers state that patients with later stages of the cancer are also enrolled in the clinical trial in order to assess how far into the disease the vaccine can be effective.

Like all science, however, these results need to be replicated and verified by everyone involved in drug development. The Food and Drug Administration will then have to look at all the information before licensing the vaccine. Later on, a group of experts in the Advisory Committee on Immunization Practices (ACIP) would give a recommendation on whether or not to recommend any cancer vaccine (besides the current HPV and Hepatitis B vaccines, which both prevent infections known to cause cancer). Public health and other private and public agencies will conduct post-marketing surveillance for safety and effectiveness, like they already do for other vaccines. While this one case in Florida may inspire hope for those battling this and other types of cancer, there is still a long way to go before the rest of the diseases that encompass cancer can be prevented by a simple shot in the arm.

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Author: René F. Najera, DrPH

I am the editor of the History of Vaccines site, an online project by the College of Physicians of Philadelphia. All opinions expressed on these blog posts are not necessarily those of the College or any of my employers. Check out my professional profile on LinkedIn: https://www.linkedin.com/in/renenajera Feel free to follow me on Twitter: @EpiRen

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