What are Cancer Vaccines?
Vaccines, also called vaccinations, are medicines that help the body fight disease. They can train the immune system to recognize and destroy harmful substances. There are 2 types of cancer vaccines:
- Prevention vaccines
- Treatment vaccines
Cancer prevention vaccines
Doctors give prevention vaccines to healthy people to keep certain cancers from developing. Like vaccines for the chicken pox or the flu, they protect the body from viruses that can cause disease. A person has to get the vaccine before the virus infects him or her. Otherwise, the vaccine will not work.
There are 2 types of cancer prevention vaccines approved by the U.S. Food and Drug Administration (FDA):
- HPV vaccine. The vaccine protects against the human papillomavirus (HPV). If the virus is long-lasting, it can cause some types of cancer. The FDA has approved HPV vaccines to prevent:
- Cervical, vaginal, and vulvar cancer
- Anal cancer
- Genital warts
HPV can also cause other cancers the FDA has not approved the vaccine for, such as oral cancer.
- Hepatitis B vaccine. This vaccine prevents hepatitis B virus (HBV) infection. Long-lasting infection with HBV can cause liver cancer.
Talk with your health care team about whether you should be vaccinated against HPV and/or HBV.
Cancer treatment vaccines
Cancer treatment vaccines, also called therapeutic vaccines, are a type of immunotherapy. The vaccines work to boost the body’s natural defenses to fight a cancer. Doctors give treatment vaccines to people already diagnosed with cancer. The vaccines may:
- Prevent the cancer from coming back
- Destroy any cancer cells still in the body after other treatments have ended
- Stop a tumor from growing or spreading
How a cancer treatment vaccine works
Antigens are substances on the surface of cells that are not normally part of the body. The immune system attacks the antigens, usually getting rid of them. This leaves the immune system with a “memory” that helps it respond to those antigens in the future.
Cancer treatment vaccines boost the immune system’s ability to recognize and destroy antigens. Often, cancer cells have certain molecules called cancer-specific antigens on their surface that healthy cells do not have. When these molecules are given to a person, the molecules act as antigens. They stimulate the immune system to recognize and destroy cancer cells that have these molecules on their surface. Most cancer vaccines also contain adjuvants, which are substances that may help strengthen the immune response.
Some cancer vaccines are made for individual patients. These types of vaccines are produced from the person’s tumor sample. This means that surgery is needed to get a large enough sample of the tumor to create the vaccine. Other cancer vaccines target specific cancer antigens and are given to people whose tumors have those antigens on the surface of the tumor cells.
Most cancer treatment vaccines are only available through clinicaltrials, which are research studies involving volunteers. But in 2010, the FDA approved sipuleucel-T (Provenge) for men with metastatic prostate cancer. Metastatic means the cancer has spread from where it began to other parts of the body. Sipuleucel-T is customized for each person through a series of steps.
- First, white blood cells are removed from the person’s blood. White blood cells help the body fight infections and diseases.
- Then the white blood cells are modified in a laboratory to recognize and target prostate cancer cells.
- Next the modified cells are put back into the person through a vein. This is similar to a blood transfusion. The modified cells teach the immune system to find and destroy prostate cancer cells.
Limitations of cancer treatment vaccines
Developing cancer treatment vaccines that work is hard because:
- Cancer cells suppress the immune system. That is how the cancer is able to develop and grow in the first place. Researchers are using adjuvants in vaccines to try to fix this problem.
- Cancer cells develop from a person’s own healthy cells. As a result, the cancer cells may not “look” harmful to the immune system. The immune system may ignore the cells instead of finding and destroying them.
- Larger or more advanced tumors are hard to get rid of using only a vaccine. This is one reason why doctors often give people cancer vaccines with other treatments.
- People who are sick or older can have weak immune systems. Their bodies may not be able to produce a strong immune response after vaccination. That limits how well a vaccine works. Also, some cancer treatments may damage a person’s immune system, limiting its ability to respond to a vaccine.
Because of these reasons, some researchers think cancer treatment vaccines may work better for smaller tumors or early-stage cancers.
Vaccines and clinical trials
Clinical trials are important for learning more about cancer vaccines. Researchers are testing vaccines for several types of cancers, including:
- Bladder cancer. Researchers are studying the effectiveness of a vaccine made from a virus modified to contain HER2 cells. These cells live on the surface of some bladder cancer tumors. The virus may help teach the immune system to find and destroy these tumor cells. Researchers are also comparing a standard bladder cancer therapy against standard therapy with a vaccine.
- Brain tumors. There are many studies testing treatment vaccines aimed at certain molecules on the surface of brain tumor cells. Some focus on newly diagnosed brain cancer. Others focus on cancer that has come back, or recurred. Several of the studies include children and teens.
- Breast cancer. Several studies are testing treatment vaccines for breast cancer, given alone or with other therapies. Other researchers are working to get prevention vaccines into clinical trials.
- Cervical cancer. The FDA has approved cervical cancer prevention vaccines. Research continues on vaccines that help treat the disease in its various stages.
- Colorectal cancer. Researchers are creating treatment vaccines that encourage the body to attack cells with antigens thought to cause colorectal cancer. These antigens include carcinoembryonic antigen (CEA), MUC1, guanylyl cyclase C, and NY-ESO-1.
- Kidney cancer. Researchers are testing the use of several cancer vaccines to treat kidney cancer. They are also testing vaccines to prevent later-stage kidney cancer from recurring. One vaccine, which a patient gets after surgery, is made from the patient’s tumor. Researchers make other vaccines from proteins found on the surface of kidney cancer cells or blood vessel cells in the tumor.
- Leukemia. Studies are looking at treatment vaccines for various types of leukemia, such as acute myeloid leukemia and chronic lymphocytic leukemia. Some are meant to help other treatments, such as stem cell transplants, work better. Other vaccines made from a person’s cancer cells and other cells may help the immune system destroy the cancer.
- Lung cancer. Lung cancer treatment vaccines in clinical trials target antigens. These include MAGE-3, which is found in 42% of lung cancers and NY-ESO-1, found in 30% of lung cancers. Others target antigens such as p53, survivin, and MUC1.
- Melanoma. Researchers are testing several vaccines, given alone or with other therapies. Destroyed melanoma cells and antigens in the vaccines encourage the immune system to destroy other melanoma cells in the body.
- Myeloma. There are several clinical trials studying vaccines in people with multiple myeloma who are near remission. Researchers are also testing vaccines in people with smoldering myeloma or who need to have an autologous stem cell transplant.
- Pancreatic cancer. Researchers are working on several treatment vaccines designed to boost the immune system’s response to pancreatic cancer cells. People receive some of the vaccine as the only treatment. Some receive a vaccine with another therapy.
- Prostate cancer. As mentioned above, sipuleucel-T is a vaccine doctors can use to treat men with metastatic prostate cancer. Now researchers want to know if the vaccine can help men with less advanced prostate cancer.