A team of Stanford University researchers has come up with a “cancer vaccine” that has proven effective in curing mice of different forms of the disease. Due to the treatment’s initial success, it might not be long before it gets tested on human patients.
According to the National Cancer Institute website, cancer vaccines are classified into two categories — preventive vaccines, which are designed to protect healthy individuals from the disease, and treatment vaccines, which strengthen the immune system in an attempt to treat existing forms of cancer. Only three individual types are officially available to U.S. patients, including preventive vaccines for human papillomavirus and hepatitis B, and a treatment vaccine for metastatic prostate cancer. The newly developed vaccine falls into the second category, and unlike other existing treatment vaccines, it does not require any customization of immune cells.
As noted on a press release posted Wednesday on the Stanford University School of Medicine website, almost all of the mice used in the study were completely cured of their cancer when the researchers injected the animals with very small amounts of two immune-stimulating agents. These included a short piece of DNA known as a CpG oligonucleotide, which works in concert with nearby immune cells to produce large amounts of the activating receptor OX40, and an antibody that sticks to OX40, thereby pushing immune T cells into action to fight the cancerous cells.
The key to the success of the Stanford researchers’ experimental cancer vaccine is the fact that the two agents are injected directly into tumors. This allows for a “pre-screening” process, which selectively activates the T cells that have specifically infiltrated the target tumor. Some of these cells, once activated, can exit the original target to find other tumors and destroy them, which could result in the vaccine curing other signs of the same type of cancer, including previously untreated metastases.
For the purposes of their study, which was published in the journal Science Translational Medicine, the researchers tested 90 mice with transplanted mouse lymphoma tumors in two separate sites. All in all, 87 of the mice were completely cured of their cancer, with the vaccine causing both the target and untreated tumor to regress, and a second treatment proving successful after the cancer returned in the remaining three mice. Further tests on mice with breast and colon cancer and melanoma tumors were similarly successful.
In yet another test, which involved the transplanting of a colon cancer cell on top of two lymphoma cells, the cancer vaccine was able to cause the regression of the two lymphoma tumors in the test mice while not affecting the growth of the colon cancer tumor in any way.
“This is a very targeted approach,” explained study co-author Dr. Ronald Levy, a professor of oncology at the Stanford University School of Medicine.
“Only the tumor that shares the protein targets displayed by the treated site is affected. We’re attacking specific targets without having to identify exactly what proteins the T cells are recognizing.”
Given the “startling” success the treatment had on mice, Levy and his colleagues are now recruiting a small number of human patients to take part in upcoming clinical trials. About 15 individuals with low-grade lymphoma will be participating in these tests, and if successful, this could lead to trials on patients suffering from other types of cancer. According to the Stanford press release, Levy is looking forward to a process where doctors inject human patients’ solid tumors with the cancer vaccine, before surgically removing the cancer to make sure the disease does not return via unexpected metastases or genetic mutations.
“I don’t think there’s a limit to the type of tumor we could potentially treat, as long as it has been infiltrated by the immune system,” he commented.