Promising cancer drug to be tested on humans
Cancer is a dangerous disease that affects more and more people worldwide. Researchers have now found that injecting tiny amounts of two immunostimulating agents into tumors in mice completely eliminates the cancer. The injection used is now to be tested on human subjects in order to be brought onto the market as quickly as possible.
The researchers at Stanford University School of Medicine found that tumors in mice can be killed by an injection. Studies on human subjects are now to follow, in the hope that the drug can be made available to patients in the near future. The experts published the results of their study in the journal "Cell Stem Cell".
Side effects are unlikely
The novel treatment is able to kill tumors in mice. It removes all traces of cancer in the animals examined. This approach works for many different types of cancer, including those that arise spontaneously, doctors say. The researchers speculate that topical application of very small amounts of the drug could serve as a quick and relatively inexpensive cancer therapy. Side effects are very unlikely with this type of treatment. When both agents were used together, the tumors were eliminated throughout the body, explains Professor Dr. Ronald Levy from Stanford University School of Medicine.
What are induced pluripotent stem cells?
So-called induced pluripotent stem cells or iPS cells are a key element in regenerative medicine. Outside of the body, they can develop into many different types of cells and tissues, which can then help repair possible damage from trauma or disease. The iPS cells could have a new use in the future, because they are supposed to train the immune system to attack tumors or even prevent the development of the tumors. The results of the current study suggest that one day it might be possible to vaccinate an individual with their own iPS cells to protect them against the development of many types of cancer.
What do induced pluripotent stem cells do?
The iPS cells are part of the investigated vaccine. The experts explain that they have strong immunogenic properties that elicit a system-wide, cancer-specific immune response. This approach has exciting clinical potential for the treatment of cancer. The iPS cells function as an anti-cancer vaccine because they are free from growth restrictions that normally occur in mature cells that make up our body tissues. The introduction of iPS cells that genetically match the recipient but cannot replicate enables the immune system to attack cancer better. iPS cells resemble tumor cells on their surface, explains Dr. Joseph Wu from Stanford University's Cardiovascular Institute. If an animal is immunized with genetically matched iPS cells, the immune system could be made to fight the development of tumors in the future, the expert adds.
How were the iPS cells made?
To produce the iPS cells, researchers take cell samples from an easily accessible source such as skin or blood. The cells are then treated with a number of genes that cause them to reset their development clock to pluripotent, the scientists explain. This allows the cells to develop into almost any tissue in the body. A key factor in pluripotency is the ability of the cells to form a tumor called a teratoma, which consists of many different cell types after the cells have been injected into animals.
How do cancer cells work?
So-called iPS cells, which are used in regenerative medical therapies, are grown in the presence of other proteins in order to encourage them to specialize or differentiate in specific cell populations before they are used clinically. It has long been known that cancer cells reflect many characteristics of immature cells in development. As part of their cancer transformation, they often lose the naturally occurring mechanisms that serve to block inappropriate cell division, the researchers say. Instead, they start to multiply quickly.
Experiments were carried out on mice
In their study, the doctors examined four groups of mice. A control solution was injected into one group, and one group received genetically identical iPS cells which had previously been irradiated. In this group, the formation of teratoms should be prevented. A third group received a general immunostimulating agent known as an adjuvant. The last group received a combination of irradiated iPS cells and an adjuvant. All animals received such an injection once a week for four weeks. Finally, a breast cancer cell line was transplanted to the mice to examine the potential growth of tumors.
The size of the tumors shrank in seven out of ten animals
One week after the transplant, it was found that all mice developed breast cancer cell tumors at the injection site. Although the tumors in the control groups grew robustly, their size shrank in seven out of ten mice that had been vaccinated with iPS cells plus adjuvant. Two of these mice were able to completely eliminate the breast cancer cells and these animals were still alive over a year after the tumor transplant. Similar results were seen when the researchers transplanted a mouse melanoma and mesothelioma cell line (a type of lung cancer) into the mice.
Active ingredient could prevent cancer months or years later
The researchers now want to investigate whether the approach also works in samples from human cancer cells and immune cells in the laboratory. If success is found, the vaccine could be given to people in the future to prevent cancer from developing months or years later. Alternatively, the iPS cells could possibly be used as part of the standard of adjuvant treatment after primary surgery (chemotherapy or radiation therapy). The researchers hope that they could also be used as immunotherapy to treat established cancers.
More research is needed
"Although much research is still needed, the concept itself is fairly simple," explains Dr. Joseph Wu of Stanford University in a press release. We use the blood of those affected to manufacture iPS cells. These cells are then re-injected to prevent future cancers. I am very excited about the future possibilities of this treatment, the expert adds. (as)