By Robert G. Bell
Typically, when we think vaccines, we think of the childhood ones that prevent such diseases as measles, mumps, and rubella. But wouldn’t it be great to have a vaccine that would prevent (and treat) the many forms of cancer? Science and medicine have been interested in immunotherapy for cancer treatment for over 100 years, starting with the work of William Coley‘s use of bacteria and bacteria lysates in patients with cancer. Cancer vaccines are intended to stimulate the patient’s immune system against tumor antigens. I have had the opportunity to work with research and development teams on several cancer immunotherapies over the years and have watched them move from a novel treatment to supportive therapy and more.
Currently there are hundreds of clinical studies utilizing cancer vaccines, and more are on the horizon. Ideally, the hope of a vaccine for cancer would not only prevent (prophylactic) cancer but also treat the cancer (therapeutic cancer vaccine). Therapeutic cancer vaccines are different from traditional preventative vaccines (e.g., for infectious diseases such as measles) in that the primary goal is to generate an active immune response against an existing cancer, not to prevent the disease. The goal of therapeutic vaccines is to express antigenic cancer fragments to initiate a T-cell-driven immune response to the cancer.
Cancer prevention vaccines are not really new. The hepatitis B vaccine, approved in 1981, was the first cancer preventive vaccine (prevention of liver cancer) to be developed and marketed, and most children in the United States are vaccinated against hepatitis B virus shortly after birth. The Food and Drug Administration (FDA) recently approved two preventative vaccines, Gardasil and Cervarix, that protect against infection by the two types (types 16 and 18) of human papillomavirus (HPV) that cause approximately 70% of all cases of cervical cancer worldwide. In 2010, FDA approved Dendron’s Provenge, the first cancer treatment vaccine for use in men with metastatic hormone-refractory prostate cancer.
From my experience and observations, cancer treatment vaccines can be effective if a majority of the tumor burden (e.g., > 90%) is removed surgically prior to administration of the cancer vaccine. Research suggests that cancer treatment vaccines may be most effective when given in combination with other forms of cancer therapy and may increase the effectiveness of other cancer therapies. We are still looking for the magic vaccine that will not only prevent but cure cancer. We are not there yet, but each day we understand a little more, and we will get there one day soon. Cancer vaccines will become more effective as we identify additional novel cancer-associated antigens, enhance the immune system towards these cancer antigens, and combine multiple antigens a single cancer treatment vaccine to produce optimal anticancer immune responses. Right now, it’s another treatment option for the patient and physician. And you are a lucky patient when you have options. Let’s keep those options coming.
Another interesting option is protein therapy, which we will discuss in our next 50 Shades of Cancer Immunostimulation blog.