There have been many treatment vaccines developed in the past few years for various types of cancers. They are still in the testing phases, but researchers are very excited about the preliminary results. These vaccines are working; results have looked promising. As of April 2017, recruitment has begun for the world's first ovarian cancer vaccination clinical trial. It will test the OncoImmunome vaccine in stage III/IV ovarian cancer patients.
There are 2 types of vaccines: The type that people are used to hearing about, preventative vaccines, and cancer vaccines, which are treatment vaccines.
They focus on treating and eliminating cancer that is already present in the body.
Cancer cells somehow escape recognition and attack by the immune system. Researchers have made advances in understanding these cells, enough to be able to design vaccines against them.
Understanding how the immune system and cancer cells interact is key to their research. New imaging technology has allowed scientists to observe cancer cells and killer T cells (a subtype of white blood cells) in the body.
What treatment vaccines do
Cancer vaccines, or vaccinations, were created to encourage a person’s own immune system to attack the cancer. They essentially train the immune system to identify and destroy harmful cells.
They are a type of immunotherapy and are used on people who have already been diagnosed with cancer. They stimulate an immune response that is more robust than it would be if left alone.
According to the American Cancer Society, vaccines target agents that cause or contribute to the development of cancer. They stimulate antibody production that bind to targeted microbes.
Most of these treatments contain adjuvants, which are substances that strengthen the immune system. These don’t provide immunity, but instead increase the immune system’s response to target what it needs to target. They amplify the immune response.
Typically, these medicines are given to people whose immune systems are capable of responding appropriately. Some doctors feel that the people who will benefit the most from current vaccines are young people, and those who have been recently diagnosed with cancer.
At this stage of research, these populations may see more success with vaccines (depending on the vaccine). This is as opposed to people who may have a compromised immune system, either from advanced cancer, cancer treatments or age.
If someone's immune system can’t be trained to respond, then the treatment won’t be as effective.
How do they work?
Antigens are found on cell surfaces and aren’t normally part of the body. Cancer cells have antigens that are specific to those cells. When the immune system attacks these antigens, it can better recognize them in the future.
The immune system has a type of memory.
The vaccines are molecules given to a patient to stimulate the immune system to recognize antigens and get rid of cancer cells. They stimulate the immune system’s memory.
Some cancer vaccines are made to be unique to specific individuals, and so are produced to go after targeted antigens.
Many of these vaccines are still in early phases of trials. Scientists have tested very small samples of patients to get an idea of how safe and viable they are.
Cancer vaccine types
- Antigen vaccines: These aren’t custom made for a specific patient. They can be for a specific type of cancer though, and use 1 or more antigens rather than targeting whole cells.
- Tumor cell vaccines: These are made from cancer cells extracted from a patient’s body, then reinjected. They are modified to increase the immune system’s response to them.
- Dendritic cell vaccines: These have seen the most success in trials. They are made from the patient’s immune cells. They expose the immune cells to cancer cells and help the immune cells turn into dendritic cells. They are returned to the body, creating a more efficient immune response against cancer. It is a complex process.
In addition to modifying existing cells, researchers are in the process of developing synthetic antigens for use in cancer preventative vaccines. They create antigens that are able to have stronger responses than the originals.
The first approved cancer vaccine
The FDA has approved a new vaccine, which is exciting progress. In 2010 a vaccine called Provenge for men with metastatic prostate cancer was approved. It was the first approved vaccine, and validates vaccines as a solid treatment option.
This sets the pace for further advancements.
Sipuleucel-T or Provenge showed a survival rate of 38 percent more patients after 3 years than a control group.
Since it targets advanced cancer, it doesn’t cure prostate cancer, but does help extend patients’ lives by several months.
The process for the prostate vaccine is as follows:
- First white blood cells are removed from the patient’s blood.
- They are modified to recognize and attack cancer cells
- The cells are put back into the patient intravenously.
Dr. James Gulley of National Cancer Institute’s Center for Cancer Research, divulged that, “Immunotherapy is still an emerging field.” They are still honing vaccine development, determining the types of people who will benefit the most, and which other therapies will best complement vaccines.
Some cancer treatments, like chemotherapy, damage the immune system. That treatment limits the body’s ability to respond successfully to a cancer vaccine.
Ideally a treatment would not impair the immune system, and would target only cancerous cells.
When a vaccine is unlikely to work on its own, doctors will combine it with other treatments, such as when a patient has a larger or more advanced tumor.
Study with promising results
In a new study, melanoma skin cancer tumors disappeared in more than half the patients who were given cancer vaccines. The patients whose tumors didn’t totally disappear were given another treatment to boost their immune systems. Some of those patients’ melanoma also then disappeared.
Researchers vaccinated the small group of patients who had tumors removed. They analyzed cancerous DNA, versus healthy cells, looking for mutations and associated neoantigens. They were able to personalize vaccines in this way, using computer models to determine which neoantigens to target.
Four of six patients had no cancer recurrence after 25 months. The other two patients who had more advanced melanoma were also then treated with therapies which block cancer’s ability to suppress the immune system. These patients also came through with flying colors, having tumor regression.
The study was kept small to determine the safety of the vaccines and assess possible side effects. The study participants experienced mild flu-like symptoms, rash, injection site reactions and fatigue. There were no serious or long-term problems.
Dr. Catherine Wu, a physician-scientist at the Dana-Farber Cancer Institute in Boston, led one of the new studies. She stated, “Many other cancers might benefit from this approach.”
Dr. Ugur Sahin at the University Medical Center of the Johannes Gutenberg University and Biopharmaceutical New Technologies Corporation, both in Mainz, Germany, led another, similar study. They created personalized vaccines for each individual’s mutated cells.
This study was slightly larger, but still small, as phase I clinical trials usually are. They needed to safely find the correct dose to maximize results and minimize side-effects.
Eight of thirteen participants stayed clear of tumors after 23 months. The rest had tumor relapses, but one of them experienced cancer regression after checkpoint-blockade therapy was used to enhance the immune system.
Researchers are testing vaccines on bladder cancer, brain cancer, breast cancer, cervical cancer, colorectal cancer, kidney cancer, leukemia, lung cancer, myeloma, pancreatic and prostate cancer.
Where are trials being conducted?
Most cancer vaccines are available only through clinical trials. Researchers have specific criteria patients need to meet to qualify for these trials.
Research studies use volunteers to conduct studies, learning about new treatments or combining other treatments. These are known as clinical trials. Participants are closely monitored and cared for during these studies.
According to cancer.net, less than 5 percent of adult patients take part in these trials, even though new treatments could offer hope. At least 60 percent of children with cancer participate in trials, and children are known to have a higher survival rate than adults with cancer.
Your doctor may know of trials, and they can also be found online on cancer.net. Your doctor may not know of all available trials, so it is good to do your own research also.
Dr. Cornelius Melief, a physician-scientist at Leiden University Medical Center in the Netherlands, said that there need to be larger studies, but that “these are exciting times. I think we are in for game changers in cancer.”
Cancer treatment vaccines are still in the early phases of study, yet are experiencing successful results. With researchers building on their knowledge with each passing clinical trial, the future of treatment is looking hopeful.