Published: Fri, February 16, 2018
Medicine | By Brett Sutton

Stem cell vaccine immunizes lab mice against multiple cancers

Stem cell vaccine immunizes lab mice against multiple cancers

The researchers injected mice with a vaccine made from these reprogrammed cells, triggering an immune response. By doing so, the adult somatic cell actually transforms into a cell that is similar to embryonic stem cells. This gives the cells their pluripotency, allowing them to turn into almost any cell in the body. "Once activated, the immune system is on alert to target cancers as they develop throughout the body", he said.

Shrinking tumors and improved survival rates meant that introducing the iPS cells taught cancer-killing T cells to find and kill the faulty, diseased cells. When the pre-prorammed DNA were injected to the subjects, it was discovered that they attached themselves to cancer cells within 48 hours.

Cancer develops when cells multiply and grow sporadically.

To be effective, anti-cancer vaccines must introduce one or more antigens into the body that activate T cells or produce antibodies capable of recognizing and binding to antigens on the surfaces of cancer cells.

For their study, the researchers experimented with four groups of mice, each injected with a specific vaccine containing modified iPS cell once a week for a month.

They have found a way of "priming" the immune system to spot, attack and kill off breast tumour cells. Another group received adjuvant, a generic immune-stimulating agent, while a third got a combination of irradiated iPS cells and adjuvant.

This is hardly is the first proposal to create a cancer vaccine, but as lead author Nigel Kooreman explained in the press release, the group's approach is powerful as it would expose the patient's immune system to a variety of cancer-specific epitopes in one go.

Just one week later, all of the mice had developed breast cancer. The fourth group served as a control.

While the study was only tested on the three most common cancers (breast cancer, lung cancer and skin cancer), Wu tells Alphr that the vaccine should be able to target other kinds of cancers too.

The tumours were rejected by 70 % of the vaccinated mice and became significantly smaller in the remaining 30%. For example, cancer cells and embryonic cells have similar gene-expression and antigen profiles, and studies from nearly a century ago showed that injecting embryonic material into animals protected them from transplanted tumors.

Another study now being prepped for human trials also stimulates the immune system to fight different kinds of cancer, but the iPS approach from Stanford presents a more personalized treatment.

In the future, a patient's blood cells or the skin may be re-programmed into iPSCs and executed as an anti-cancer vaccine or as consecutive booster after surgery, radiation therapy, or chemotherapy.

The researchers found that iPSC vaccines prevented tumor growth in syngeneic murine breast cancer, mesothelioma, and melanoma models in a prophylactic setting.

The scientists say that their new method shows promise as a personalized way to someday preventatively immunize humans against their own cancers.

The concept worked in tests on mice - but it will be some time before a vaccine could be available to humans. So a follow-up iPSC vaccination to boost the patient's own anti-cancer response would be highly valuable. As a next step, we are now setting up and performing in vitro experiments to validate the efficacy and safety of the vaccine on human samples. "Based on these results, we will decide which cancers we should start with first, and then we can start thinking about clinical trials". The advantage of using whole cells is that all the antigens they harbour - including, crucially, any so far undiscovered by researchers - are passed on to the host.

A study conducted in 2015, for example, found that the differences between iPS cells and parent cells were very small, with any mutations unlikely to be harmful or unsafe to the human body.

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