Scientists improve cancer immunotherapy

We train dogs to do tricks for a treat and we train our children to behave well and get good grades in school. With the help of recent developments in biomedical research, we can also train white blood cells to specifically look for and kill only cancer cells.

Scientists at Duke University have figured out a way to successfully cure a type of a brain cancer known as gliomas in mice using an artificial protein that allows them to program killer cells, or T-cells, to become ultimate protectors of our immune system.

Gliomas are tumors that grow in either the brain or the spine. They arise from glial cells, which serve important purposes in the brain including homeostasis to production of myelin. In fact, gliomas make up 30 percent of all brain tumors and are responsible for 80 percent of all malignant tumors.

The newly developed T-cells are able to specifically target cells like those in gliomas. Just like patrol officers are trained to know when something is out of the ordinary, these programmed killer cells are trained to sense when the body is being invaded by specific type of cancer cells.

These killer cells are in constant search for cancer cells and as soon as they come in contact with them, they can attack and kill them. This novel system shows some great promise for future treatment of brain tumors in humans, as there was no evidence of side effects found in the study done in mice.

In this study, scientists used what is known as bispecific antibodies, an artificial protein with two arms: one that recognizes cancer cells and another that recruits killer cells of animal’s immune system.

These antibodies are highly sensitive, as they recognize only cancer-specific markers found on particular type of gliomas. Essentially, when antibodies are injected in an animal, they create a bridge between cancer cells and killer cells. As a result, killer cells can activate and mount an attack on cancer cells.

This is analogous to giving special pair of glasses to patrol officers that allow them distinguish crooks from the general public. In the study, scientists found that their therapy resulted in increased survival in mice with large tumors and achieved complete cures at rates up to 75 percent. In six out of eight mice, therapy resulted in complete cure from cancer with no side effects.

There are many advantages of this novel technique over other immune therapies under investigation. A substantial amount of evidence suggest that T cells are predominant effectors in the immune system-mediated eradication of cancer.

However, previous attempts to activate and mount an attack via T cells have been unsuccessful for many reasons. Such a technique requires growing and genetically manipulating T cells in the lab, outside of patient’s body, which is very risky for patients.

Furthermore, none of the previous techniques have been able to specifically target cells as well as these T-cells. Previous attempts have led to unwanted toxicity and destruction of healthy tissues due to nonspecific activation of T cells.

Although this study was conducted in mice with gliomas, a type of brain and spinal cord cancer, this novel technique could be applied to other types of cancer, diseases caused by pathogens invading our body, and diseases that involve build up of unwanted proteins such as Alzheimer’s disease and Parkinson’s disease among others.

The only thing scientists would need to design is an artificial protein that could recognize other types of cancer cells, unwanted proteins or invading pathogens.

The real challenge in this field is designing those artificial proteins with desired specificity. Recently, there has been some great progress in targeted immunotherapy. Researchers at the Johns Hopkins Hospital and Medical Centers have figured out a way to treat myasthenia gravis, an autoimmune neuromuscular disease leading to fluctuating muscle weakness and fatigability, using a similar technique. Scientists at the University of Pennsylvania have successfully treated leukemia using a similar method that supercharges patient’s white blood cells to kill cancer cells.

Since this study was conducted in mice, more research is being planned to determine whether the therapeutic benefits reported here can be replicated in humans as well. Nevertheless, this new therapy shows great potential for future treatments of human brain tumors and other types of cancer.

The lead researchers are planning on conducting a study in which they would be using human specific markers on mice T-cells and see if they can replicate the findings of this study.