Certain Types of Cancer Can Be Slowed With Vaccines

Immunotherapy is rapidly emerging as a dynamic tool to fight disease, especially diseases that are hard to treat. With cancer immunotherapy, the immune system is leveraged to fight tumors in novel ways. Immunotherapy interventions can either directly stimulate the immune system or present the immune system with artificial proteins, or antigens, to thus train the immune system on tumors.

Cancer treatment vaccines are a form of immunotherapy used to treat cancers that already exist. More generally, cancer treatment vaccines are biologics, or biopharmaceuticals. Other biologics include blood components, gene therapy, allergenics, and other vaccines.

Currently, the only cancer vaccine that the FDA has approved is called Provenge to treat prostate cancer.

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Cancer Treatment Vaccines

Antigens are substances that trigger an immune system response. Many cancer treatment vaccines in development provide cancer-associated antigens to dendritic cells. Dendritic cells are present in those tissues that are in contact with the external environment, such as the skin and the inner lining of the nose, lungs, stomach, and intestines. They can also be found in the blood.Furthermore, immunostimulatory molecules present in the cancer vaccine upregulate, or increase production, of molecules needed to eventually interact with T cells. Of note, cancer-associated antigens can be specific either to one type of cancer or a group of several cancers.

These activated dendritic cells migrate to lymph nodes, which are small clumps of immunologic tissue located throughout the body. Once these activated dendritic cells make it to a lymph node, they present the cancer-specific antigen to T cells. Activated T cells then travel throughout the body and target cancer cells that present with the antigen and lyse, or break down, the cancer cell. (More technically, activated CD4+ T cells produce cytokines which facilitate the maturation of CD 8 cells, which after maturation travel throughout the body.)

According to the FDA, several cancer vaccines currently in development use bacteria, viruses, or yeast as vehicles, or vectors, to transport antigens. Bacteria, viruses, yeast and so forth are naturally immunogenic and trigger an immune response on their own; however, they are modified so as not to cause disease.

Alternatively, cancer treatment vaccines can be formulated using DNA or RNA that code for antigens. This genetic material is then incorporated into cells which then produce the antigens. The hope is that these modified body cells will then produce enough cancer-associated antigens to induce a vigorous immune response to kill off tumor cells.

Ultimately, three criteria must be met for tumor cells to be destroyed by a vaccine:

  • a sufficiently large quantity of immune cells with pronounced affinity for cancer cells must be produced
  • these T cells must be able to infiltrate the tumor
  • these T cells must start working at the tumor site to cause site-specific damage

How Effective Are Cancer Vaccines?

During the past several years, hundreds of cancer (dendritic-cell) vaccines have been tested. However, response rates to these vaccines are very low—about 2.6%. In fact, other types of immunotherapy have proven to be much more effective, which has influenced many experts to question our "obsession" cancer therapeutic vaccines.

So if cancer therapeutic vaccines are rarely effective in humans, why are we continuing to invest resources and time into the development of cancer vaccines? There are at least three reasons explaining our interest in this type of intervention.

First, vaccines have been effective at preventing cancer, and this success has carried over to treatment of cancer with vaccines. In other words, the work we've done developing preventive cancer vaccines has taught us lots about the immunology of cancer cells and has provided a theoretical framework for the development of cancer treatment vaccines. There are currently two vaccines that prevent cancer: the hepatitis B vaccine prevents liver cancer, and the human papillomavirus (HPV) vaccine prevents throat, cervical, anal, and other cancers.

Second, cancer therapeutic vaccines are easy to administer and cause few serious adverse effects.

On a related note, much cancer vaccine research has been done on the basic medical sciences level using animal models. Mice, as one can probably infer from their size, behaviors and furry appearance, are different from human beings. Thus, any success we see in treating these animals with cancer therapeutic vaccines doesn't necessarily translate to humans.

More specifically, although cancer vaccines have been proven to be effective in animals, it's infrequent to discover any such effect in humans. Specifically, there is only one cancer therapeutic vaccine approved by the FDA for the treatment of cancer in humans: Provenge. However, there's another prostate cancer vaccine currently in Phase 3 trials that has proven to be effective: Prostvac.

Before we look at both Provenge and Prostac, let's brush up a little on our knowledge of prostate cancer.

Prostate Cancer

Aside from skin cancer, prostate cancer is the most common cancer affecting American men. Although nearly 1 in 7 American men develop prostate cancer, far fewer die of the disease (about 1 in 39). Instead, men often die of some other disease first, like heart disease. Nevertheless, in 2016, there were 26,120 deaths caused by prostate cancer.

Because of widespread testing for prostate-specific (PSA) antigen, a biomarker for prostate cancer, we've been able to detect cases of prostate cancer earlier, while the cancer is still confined to the prostate, More rarely, men present with prostate cancer that has metastasized or spread to the bones and becomes deadly.

Factors that increase risk for prostate cancer include older age, African American race and family history.

Most people with prostate cancer don't need treatment and instead are observed by their physicians. Treatment for prostate cancer can include expectant management (active surveillance), surgery (prostatectomy or removal of the prostate), radiotherapy and androgen, or sex hormone, deprivation.


Provenge or sipuleucel-T is a dendritic-cell vaccine that was approved by the FDA in 2010. Provenge is what's known as an autologous cellular immunotherapy and is used to treat metastatic disease that hasn't spread very far yet (minimally invasive). Furthermore, Provenge treats prostate cancer that isn't sensitive to hormones (hormone refractory).

On a related note, hormone refractory cancers respond to hormone-deprivation therapies, or drugs that mess with androgens, or sex hormones (think medical castration).

Provenge is prepared using a patient's white blood cells (peripheral blood mononuclear cells) pulsed with a protein called granulocyte-macrophage-colony-stimulating factor (GM-CSF) and prostatic acid phosphatase, or PAP, a prostate cancer antigen.

The reason why GM-CSF is given with the antigen PAP is that researchers believe that GM-CSF facilitates the presentation of the antigen. Of note, the peripheral blood mononuclear cells serve as the dendritic cells to which the antigen is presented.

In one study, Provenge extended median survival by about four months compared to placebo.

Adverse effects of Provenge include the following:

  • fever
  • chills
  • fatigue
  • back pain
  • headache

During clinical trials of Provenge, a few men experienced more serious adverse effects including difficulty breathing, chest pain, irregular heartbeat, fainting dizziness and fluctuations in blood pressure. Thus, people with heart and lung problems should discuss these conditions with their health care provider.

A Phase 3 trial of another vaccine, Prostvac, in asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer was demonstrated to be safe and well tolerated but it had no effect on overall survival or the number of patients alive without events. Combination therapies are currently being explored in clinical trials.

What Is Imlygic?

In 2015, the FDA approved an Imlygic, an oncolytic vaccine for the treatment or malignant melanoma that's inoperable. Although technically not a cancer therapeutic vaccine, Imlygic has secondary effects similar to cancer therapeutic vaccines.

Oncolytic viruses are a type of immunotherapy where a genetically engineered virus is injected directly into a melanoma tumor and lyses or breaks tumor cells down. In addition to breaking down the cells, these viruses have a more general effect of eliciting an antitumor effect similar to anticancer vaccines.

A Word From Verywell

Currently, the use of cancer vaccines in clinical settings is limited. Additionally, as mentioned earlier, it's been really hard to find cancer vaccines that have any effect on human participants. It's unlikely that we'll see cancer vaccines used to treat a variety of cancers anytime soon.

Nevertheless, cancer vaccines represent advancements of the immune system as well as the field of immunotherapy. The better we understand the specifics immune system, the better we can target therapies that could someday save lives.

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  1. Y, Frohlich MW, Schellhammer PF; IMPACT Study Investigators. Sipuleucel-T immunotherapy for castration-resistant prostate cancer. N Engl J Med. 2010. 363(5):411-22. doi:10.1056/NEJMoa1001294

Additional Reading
  • Goswami S, Allison JP, Sharma P. Immuno-Oncology. In: Kantarjian HM, Wolff RA. eds. The MD Anderson Manual of Medical Oncology, 3e. New York, NY: McGraw-Hill; 2016. Accessed May 19, 2016.
  • Kantoff PW et al. Overall Survival Analysis of a Phase II Randomized Controlled Trial of a Poxviral-Based PSA-Targeted Immunotherapy in Metastatic Castration-Resistant Prostate Cancer. J Clin Oncol. 2010 Mar 1; 28(7): 1099–1105.
  • Pienta KJ. Chapter 96. Prostate Cancer. In: Halter JB, Ouslander JG, Tinetti ME, Studenski S, High KP, Asthana S. eds. Hazzard's Geriatric Medicine and Gerontology, 6e. New York, NY: McGraw-Hill; 2009. Accessed May 22, 2016.
  • Rosenberg SA, Yang JC Restifo NP. Cancer Immunotherapy: Moving Beyond Current Vaccines. Nat Med. 2004 September: 10(9): 909-915.