In the video below, Hank Green of the SciShow talks about an exciting new development in cancer treatment: A potential cancer vaccine.
Researchers at the Stanford University School of Medicine have been working on two novel immune-stimulating agents. They have injected these agents into the solid tumors of mice and found that the agents eliminated all traces of cancer in the mice, even when the cancer had spread to other parts of the body (metastasized).
87 out of 90 mice were cured of lymphoma tumors by the treatment. The cancer did return in three of the mice, but a second treatment caused those tumors to regress, as well.
Not a Traditional Vaccine
Although the researchers are dubbing this treatment a vaccine, it does not work like traditional vaccines, which are meant to impart immunity against disease and thus keep you from ever getting sick. This treatment works after cancer has already occurred. They stimulate the immune system in a similar way, but they are meant to be injected after you already are sick.
This is not actually a completely novel treatment. Immunotherapy treatments have already been approved for use in human cancer patients. For example, senior author of the study Ronald Levy, MD, professor of oncology, led a team that developed rituximab, a monoclonal antibody which was one of the very first immunotherapy cancer treatments approved for use in humans.
However, these new treatments are unlike previous treatments in that they do not rely on bodywide immune stimulation which can cause adverse side effects, nor are they as complicated and expensive as other treatments which require immune cells to be removed from the body and genetically engineered to fight tumor cells. This new approach uses small injections of two agents directly within the tumor itself. Amazingly, this has bodywide effects.
Our body already has ways of fighting cancers. Just as our immune system fights invading organizms that makes us sick, it fights cancer cells. For example, cancer-fighting T cells can recognize the abnormal proteins on cancer cells and then infiltrate the cell to attack the destroy the tumor. But, tumors find ways to suppress the activity of these T cells. For many years, researchers have been trying to find ways to improve the immune system’s ability to fight cancer. Levy’s treatment works by injecting agents directly into tumors to reactivate cancer-specific T cells.
One of the agents is a short piece of DNA called CpG oligonucleotide, which helps to amplify expression of a receptor on T cells called OX40. This is an activating receptor. The other agent is an antibody which binds to OX40 and thus activates the T cells, which go to battle against the tumor. Here, the treatment is targeting those T cells that have already infiltrated the tumor, so they are already primed to fight it. Now, they are turned on and ready to fight.
But it doesn’t stop there. Some of the T cells then leave the tumor to go find and destroy any identical tumors anywhere in the body. Mice prone to breast cancer were also treated, which prevented them from developing further tumors after the first sign of cancer was treated.
A Cancer Treatment and a Vaccine?
This treatment is highly specific to the tumor treated. What this means is that if a certain cancerous tumor is treated, all such tumors which have arisen from that tumor will be affected. For example, in one experiment, two lymphomas and one colon cancer tumor were transplanted into mice, but only a lymphoma site was treated. This caused both of the lymphomas to regress, but the colon tumor was unaffected. Once the T cells are activated, they only recognized the protein targets from the originally treated site. In this way, however, they continue to seek and destroy this specific cancer in the future. This is why the treatment is being called a vaccine. It does treat existing cancer but also prevents the cancer from occuring again in the future. It provides, in a sense, immunity.
Novel tumors from other types of cancer will not be affected. However, the team thinks the treatment will work on almost any type of tumor, as long as it has been infiltrated by the immune system.
One of the treatment agents is already approved for use in humans, but now, a human clinical trial is being assembled, meant to involve 15 patients with low-grade lymphoma. If successful, this treatment will be a major advance in the treatment of cancer.