As a former drug-formulation chemist, I have been following the debate and discussion around the recent outbreak of measles in the U.S. among unvaccinated individuals with deep interest because I wonder if this turning away from vaccines could also mean that such individuals may turn away from other vaccines, such as those for preventing cancer. It is commonly understood that it is better to prevent disease (Centers for Disease Control and Prevention web link) than to treat it after it has occurred. (By the way, the stunning image is of a measles cell.)How vaccines work in prevention of disease is as follows. The body’s mechanism for protection and prevention of disease is through the immune system and when germs enter the body, the immune system produces antibodies to fight these germs (antigens). This is where vaccines come in. Vaccines contain the same antigens (or parts of antigens) that cause a disease, but these antigens are either killed, or weakened to the point where they do not cause the disease. For measles alone, efforts in countries to increase access to measles vaccination has reduced measles deaths worldwide (web link) by 78% from an estimated 562,400 deaths in 2000 to 122,000 in 2012.The CDC and the American Academy of Pediatrics (AAP) (link to recommended immunization schedule) recommend that healthy children get vaccinated against 14 diseases by age 2. Increasingly, it appears that parents are wary or opposed to vaccinating their children believing that vaccines are to blame for the rise in kids with autism spectrum disorders (ASD).
This idea first made headlines in 1998, when Andrew Wakefield, M.D., a British gastroenterologist, published a fraudulent study of 12 children inThe Lancet that linked the measles, mumps, and rubella (MMR) combination vaccine with intestinal problems that he believed led to autism. The Lancet subsequently retracted the article as described by Steven Novella, in an article, titled, The Lancet retracts Andrew Wakefield’s article, as the study itself has not stood the test of time. The results could not be replicated(Journal of Medicine Virology link) by other labs and a decade of subsequent research (sbmadmin Blog link) has sufficiently cleared the MMR vaccine of any connection to ASD. One result of non-vaccination was seen recently in the U.S., where a measles outbreak starting at Disneyland (link to timeline) effected at least 59 people across the country.
As the vaccination debate (link to Parent.com website article) continues for and against the use of vaccines on children to prevent childhood diseases mainly related to viruses, many different types of vaccines are now being studied to treat a variety of cancers. The following article describes some of the latest vaccine work being done: What’s new in cancer immunotherapy research? (link to article). The question whether cancer vaccines will be accepted remains open, but the latest reports of vaccine skepticism have not deterred scientists from continuing their research.
Cancer Virus Vaccines
Let’s start by describing some cancer virus vaccines (website link). Most of us know about vaccines given to healthy people to help prevent infections, such as measles and chicken pox. These vaccines use weakened or killed germs, like viruses or bacteria, to start an immune response in the body. Getting the immune system ready to defend against these germs helps keep people from getting infections. Vaccines for hepatitis B and human papilloma viruses, in a way, can be considered cancer virus vaccines. They may help protect against some cancers, caused by the viruses but they don’t target cancer cells directly. These types of vaccines are only useful for cancers known to be caused by infections.
What about vaccines for non-virus cancers? These non-virus vaccines are not yet a major type of treatment for cancer. The development of vaccines to fight cancer has proven to be difficult due to the complexity of the immune system. But, researchers are using the knowledge gained in recent years to improve how they develop cancer vaccines. For example, vaccines are now often given along with other substances (called adjuvants) that help boost the body’s immune response, which might help the vaccines work better. For information on the HPLC analysis of adjuvants using our systems, check out this method, described in Application Note 1082, Direct Analysis of Multicomponent Vaccine Adjuvants by HPLC with Charged Aerosol Detection (PDF link).
Non-Cancer Vaccines
There are four new types of non-virus cancer vaccines being developed, as noted on the www.cancer.org web site and described below.
Tumor cell vaccines are made from actual cancer cells that have been removed from the patient during surgery. The cells are altered in the lab to make them more likely to be attacked by the patient’s immune system and then injected back into the patient. Their immune system then attacks these cells and any similar cells still in the body. The paper by W. Whitford, titled, Using Disposables in Cell-Culture– Based Vaccine Production, (link to abstract), describes cell culture techniques that have enhanced the vaccine development process.
Antigen vaccines boost the immune system by using only one antigen (or a few), rather than whole tumor cells. The antigens are usually proteins or pieces of proteins called peptides. Antigen vaccines can be specific for a certain type of cancer, but they are not made for a specific patient. An excellent presentation, titled, Introduction to Proteomics (web link to downloadable Powerpoint file), describes basic concepts of amino acids, peptides, and proteins and goes into significant depth regarding methods of analysis.
Dendritic cell vaccines have shown the most success so far in treating cancer. Dendritic cells are special immune cells in the body that help the immune system recognize cancer cells. They break down cancer cells into smaller pieces (including antigens), then hold out these antigens so other immune cells, called T cells, can see them. The T cells then start an immune reaction against any cells in the body that contain these antigens. For additional information on dendritic cells, see the article by Dr. A. Mandal, MD, titled, What are Dendritic Cells? (web link).
Vector-based vaccines use special delivery systems (called vectors) to make them more effective. They aren’t really a separate category of vaccine; for example, there are vector-based antigen vaccines. Vectors are special viruses, bacteria, yeast cells, or other structures that can be used to get antigens into the body. The vectors are often germs that have been altered to make sure they can no longer cause disease. To learn how The Cell Factory system is used in the generation of recombinant viral vectors, read our cell culture case study, titled, Optimized cell culture: for bench and beyond (pdf link). Vectors can be helpful in making vaccines for a number of reasons. First, they can be used to deliver more than one cancer antigen at a time, which might make the body’s immune system more likely to mount a response. Second, vectors such as viruses and bacteria might trigger their own immune responses from the body, which could help make the overall immune response even stronger. Finally, these vaccines might be easier and less expensive to make than some other vaccines.
Do you think there will be an effective cancer vaccine in your lifetime? If so, would you get vaccinated? Tell us in the comments section; we look forward to hearing from you.
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