Cancer cells always seem to have a way of evading the body’s natural defenses and cell death. Thus, cancer has proved to be one of the most difficult diseases to treat. However, the prognosis for the disease is shifting its course. Recently, researchers across the world have begun to create vaccines that fight cancer cells using the body’s own “police force,” or immune system. The immune system usually has difficulty identifying cancer cells as harmful enemies because cancer cells are not foreigners, but rather the body’s own cells. Meanwhile, cancer vaccines along with other targeted treatments provide a way for the body to recognize which cells are uncontrollably proliferating by attaching protein markers to them. Society is looking at a new age in treatment that is coming together at an unheard-of pace.
There are two types of cancer vaccines: autologous and allogeneic. Autologous vaccines are made from cancer cells that are taken from the human body, and then reinserted back into the body to mark matching cells as antigens. While autologous vaccines are promising because of their adaptability to the cancer patient, they are limited by their steep price and chance that scientists may not be able to extract cells from a cancerous growth. Allogeneic vaccines are currently more prevalent than autologous vaccines since they are made from an already cultivated batch of cancerous cells from previous clinical trials; however, the vaccine’s effects may only be temporary because of the adaptable nature of cancer cells.1 Having such vaccines allows for proactive care, which can attack the disease at its source. Now patients can effectively have their immune system ready for cancers, especially if they are thought to have a genetic predisposition for the disease.
These treatments have already started to become mainstream with autologous vaccines such as Panvac and Gardisil hitting the market. Panvac is a type of vaccine that targets the body’s own immune system as a way to fight cancer. The vaccine consists of the patient’s own cells that have been modified by adding viruses that code for proteins associated with cancer cells.2 The body’s own T-Cells are able to recognize these proteins as antigen markers and hone in on cancerous cells. Another vaccine called Gardisil has preventive effects on certain kinds of cancer. It targets HPV antigens that are proteins commonly associated with cancerous growths. These proteins are used in the laboratory to make four different types of “virus-like particles,” or VLPs, that correspond to HPV types 6, 11, 16, and 18.3 Meanwhile, at the University of Pennsylvania, the research pipeline is fully in effect with a breakthrough in a vaccine against Chronic lymphocytic leukemia (CLL), which is a cancer of the white blood cells. This CLL vaccine has been able to send a large proportion of its patients’ cancers into remission for more than a year and could prospectively be changed in order to target other cancers.4 Therefore, cancer vaccines begin treatment at the inception of the disease, but are evolving to the next step of eliminating the cancerous cells that already exist as well. The potential growth in the field is almost limitless and should appear to continue as long as interest remains in the long-term results of vaccines.
Although researchers have identified many cancer-associated antigens, these molecules vary widely in their capacity to stimulate a strong anticancer immune response. Therefore, there remain many avenues to look into for future research. Two major areas of research aimed at developing better cancer treatment vaccines involve strengthening current vaccine-based treatments and probing for more effective protein markers. Researchers are also looking for ways to combine multiple antigens into a single cancer vaccine for more comprehensive results.5 However, one of the most promising fields of cancer vaccine research aims at better understanding the basic biology underlying the interaction between the immune system and cancer cells. New technologies are being created as part of this effort. One new type of imaging technology allows researchers to observe killer T cells and cancer cells interacting inside the body.6 Researchers are also trying to identify the mechanisms by which cancer cells evade or suppress anticancer immune responses.7 Ultimately, this will help fight the disease after the initial usage of vaccines and further prolong a patient’s life. For example, some cancerous cells produce chemical signals that attract white blood cells known as regulatory T cells, or Tregs, to a tumor site. These Tregs are used to suppress the destructive activity of killer T Cells, which would normally be able to identify certain cancerous cells. It has been suggested that combining cytokine suppressor drugs, which allow for a greater concentration of active killer T Cells, with a cancer vaccine would create the most effective solution.8 Therefore, despite the many varieties of cancer, there appears to be just as much diversity in the vaccines that intend to end them.
In the long term, cancer research will revolutionize both the cost structure and the way in which patients are treated. However, the effects of these changes on doctors are something that cannot be overlooked. In order to better frame cancer from a doctor’s perspective, I had the chance to sit down with one of the finest minds in the field of cancer research and medical care, Dr. Richard Schilsky. Dr. Schilsky has worked at the University of Chicago Medical Center since 1984 and served as chairman of the Cancer and Leukemia Group B (CALGB), the largest and oldest cancer clinical trials group in the United States until 2010. When posed the question of how cancer treatments have changed, he spoke of his own specialization in cancer drugs. For several decades, the drugs used for cancer treatment were non-specific (they were not individualized). The goal of this “cytotoxic chemotherapy” was to destroy cancer cells, yet in the process, it also ended up destroying the surrounding tissue as well. However, Dr. Schilsky reiterated that, “We are still using these drugs but in a more limited way.” For example, he spoke of the increased prevalence of oral drugs that “target the molecular drivers of cancer cells” much like cancer vaccines have been shown to do. The changes in the cancer field as a whole reflect a paradigm shift in order to “understand at the molecular level what makes the cancer tick.” Furthermore, Dr. Schilsky spoke of the “complementary” processes that aid in cancer detection. Most scanning techniques of the human body for the disease are anatomical, such as MRI (Magnetic Resonance Imaging) and reflect the actual contours of the scanned area. However, with scanning methods such as the PET (Positron Emission Tomography), there is hope to more readily see the effects of treatments on areas with cancer. The PET scan for example is able to pick up on FDG molecules, which are effectively glucose-type molecules with a radioactive-Fluorine atom. Cancer cells are more active than the average cell so they take up more glucose and, in the process, FDG that can be monitored by the scan. These tests can provide information on whether the mass is still present and its relative size.
Doctors themselves have also had to adapt to the new findings in cancer. The effects of cancer are multifarious in the medical field. The expected growth and higher demand for cancer vaccines and other similarly targeted treatments over previous cancer treatments may adversely affect cancer chemotherapy and radiation fields. Dr. Schilsky emphasized a change in the reimbursement for oncologists. Previously oncologists were paid mainly for buying, prescribing, and administering cancer treatments. However, this system is being rethought as such treatments are not useful and their counterparts can be fulfilled without the need for a doctor present. “I no longer have to be the one dispersing the drug as it has been for intravenous chemotherapy,” said Schilsky. In addition to the shift in reimbursement, medical schools and residency programs will also change to teaching the usage of newer methods of treatment. However, “medical schools are in a way the last responders,” to changing standards in cancer care due to the lengthy approval process, Schilsky explained.
The prognosis of cancer is slowly changing and with it comes hope for the future. “We are making more progress now than in any other time in our history,” as Dr. Schilsky aptly puts it. We have come a long way in treating cancer and have a ways to go yet the discoveries that keep pouring in allow for an optimism unheard of decades ago. Dr. Schilsky emphasized this when he said “A person diagnosed with cancer in the 1970’s had a 50/50 chance of surviving. Today they have a two thirds chance.” We have been able to contain the spread of cancer and save lives, yet our ultimate goal is to eradicate this disease, which begins with a new age in its treatment.
- American Cancer Society, “Cancer Vaccines.” Accessed January 17, 2012. http://www.cancer.org/Treatment/TreatmentsandSideEffects/TreatmentTypes/Immunotherapy/immunotherapy-cancer-vaccines.
- Carollo, Kim. “Cancer Vaccine Shows Early Promise.” Accessed January 17, 2012. http://abcnews.go.com/blogs/health/2011/11/08/cancer-vaccine-shows-early-promise/
- Lowy Dr., Schiller JT. “Prophylactic human papillomavirus vaccines.” Journal of Clinical Investigation 116, no. 5 (2006):1167–1173
- Begley, Sharon. “Could This be the end of Cancer?” Accessed January 17, 2012. http://www.thedailybeast.com/newsweek/2011/12/11/could-this-be-the-end-of-cancer.html
- Schlom J, Arlen PM, Gulley JL. “Cancer vaccines: moving beyond current paradigm.” Clinical Cancer Research 13, no. 13 (2007): 3776–3782
- Ng LG, Mrass P, Kinjyo I, Reiner SL, Weninger W. “Two-photon imaging of effector T-cell behavior: lessons from a tumor model.” Immunological Reviews. 221 (2008):147–162.
- Garnett CT, Greiner JW, Tsang KY, et al. “TRICOM vector based cancer vaccines.” Current Pharmaceutical Design 12, no. 3 (2006): 351–361
- Zou W. “Regulatory T cells, tumour immunity and immunotherapy.” Nature Reviews Immunology 6, no. 4 (2006): 295–307.
- US Government. “Vaccine in leg.” Wikimedia Commons. 15 Apr. 2005. http://commons.wikimedia.org/wiki/File:Vaccine-in-leg.jpg (accessed February 5, 2012).
- Langner, Jens. “PET image.” Wikimedia Commons. 2010. http://commons.wikimedia.org/wiki/File:PET-image.jpg (accessed February 5, 2012).
Jawad is a first-year student at the University of Chicago majoring in economics and biological sciences. He has interests in both medicine and financial consulting and hopes to apply his passion for both of these topics in his articles. Follow The Triple Helix Online on Twitter and join us on Facebook.