NEW SCIENTIFIC STUDIES

A new study from Stanford University has found that mice injected with inactivated induced pluripotent stem cells (iPS) show significant responses of the immune system to a variety of cancers. If the study can be replicated in humans, this research could pave the way for personalized treatment of cancer.

This type of cells demonstrated a "strong immune response" against breast, lung and skin cancers in mice and also prevented relapse in rodents with tumors that had been eliminated, the scientists explained.

"What surprised us most was the effectiveness of the iPS vaccine in reactivating the immune system to attack cancer," said Joseph Wu, of the Stanford Cardiovascular Institute.

Induced pluripotent stem cells are cells that can be extracted from adult cells, for example from skin or blood samples, and then can be genetically treated to return to a pluripotent stage, meaning they can grow on any type of cell in the human body .

The first big revelation in the new research came when the Stanford team discovered that iPS are superficially very similar to tumor cells, suggesting a possible use to help "train" the immune system to better attack the cancer. In testing the theory, the researchers administered a group of mice the potential cancer vaccine: inactivated genetically matched iPSCs in combination with a generic immunostimulant agent known as an adjuvant. After four weekly injections of the vaccine, the mice were implanted with mouse breast cancer cells.

In the control groups, the cancer grew and developed, but in 70 percent of the vaccinated mice the tumors were significantly reduced, while the cancerous cells were completely eliminated in two mice, which remained alive for more than a year after of the experiment. it is subsequently replicated using skin cancer cell lines and lung cancer.

After this finding, 75 mice received versions of the iPS vaccine created from stem cells inactivated by irradiation.

In four weeks, 70% of the vaccinated mice completely rejected the newly introduced breast cancer cells, while the remaining 30% had significantly smaller tumors.

The effectiveness of this vaccine was also validated for lung and skin cancers.
To be effective, cancer vaccines must introduce one or more antigens in the body that activate the T cells, which are part of the immune system, or produce antibodies capable of recognizing and binding antigens on the surfaces of cancer cells.

One of the biggest challenges for immunotherapies against cancer is the limited amount of antigens that can be presented to the immune system at any given time.
The Stanford study uses an animal's own cells to create an iPS-based cancer vaccine that targets multiple tumor antigens simultaneously.

The use of complete iPS eliminates the need to identify the most optimal antigen to attack in a particular type of cancer.
"We present the immune system with a greater number of tumor antigens than those found in iPS, which makes our approach less susceptible to immune evasion by cancer cells."

The researchers also combined iPS with an immune booster, a fragment of bacterial DNA called CpG that has been considered safe in human trials.

The next step will be to repeat the experiment with human tissues. And if successful, they believe that administering a vaccine to people with their own irradiated iPS could prevent the development of tumors for months or even many years. Although as the researchers indicate, there is still much work to be done.

For the lead author, this approach "may have clinical potential to prevent tumor recurrence or to attack distant metastases."

Wu and his colleagues discovered that a large number of the antigens present in the iPS cells are also present in the cancer cells.