In part 3 of a series on cancer treatments we take a look at how the body's own cells may someday be the front line of defense in battling cancer.

Doctors have a new ally in the war against cancer – the immune system of the patient they’re treating.

Dr. Howard Kaufman, the associate director for Clinical Science and chief surgical officer at the Rutgers Cancer Institute of New Jersey, says immunotherapy focuses on using the body’s own immune system to treat cancer.

He believes this makes sense because “the immune system is the part of the body that really specializes in defending the body from invaders. Sometimes those invaders come from outside, for example bacteria and viruses, and sometimes they can be inside, such as a cancer cell.

Kaufman said for many years, doctors have known cancer cells can illicit an immune response in some patients, and may even wipe out cancer in rare instances. Knowing this information, a lot of work has been done to try and stimulate the body’s natural immune system as a way to treat cancer.

The doctor said when this does work the response is favorable.

“We often get very durable, if not complete responses in many patients, and we’re even beginning to think that we might be able to cure some patients even with advanced metastatic disease by the use of these immune therapies,” he said.

According to Kaufman, if you stimulate the immune system too much you can get what’s called autoimmunity, where the immune system can start to attack the body’s normal tissues, but that seems to be easily controlled with different drugs.

“We’ve learned a lot about the biology of how this works, and so we think that the T cells, which are part of the body’s white blood cells, are really important to eradicating cancer. When you have a drug that can specifically activate the affecter T cells in the body, we seem to get a very specific effect in getting rid of the cancer,” he said.

Kaufman said T cells are very complex and they have more protein than any other cell in the human body, and for that reason they’re tightly regulated because they have to be quickly mobilized, then cleared out so you don’t get an autoimmune reaction. However,  when researchers manipulate a T cell and leave it in the “on” position for a longer period of time “we’re seeing absolutely dramatic reductions across a variety of different cancers.”

Kaufman said so far the FDA has approved three different drugs to stimulate T cells but many more are in the pipeline. Medical professionals, he added, have also been working with oncolytic viruses “that can actually infect tumor cells, they will replicate and kill the tumor cell and then they can generate an immune response. He added that when these viruses infect normal cells they can’t replicate, so they have a very important safety feature."

“This could really be a major game-changer in the field because these have been very well tolerated. Side effects are not bad. These are not the kind of permanent side effects that you can get with chemo-therapy, they’re not as debilitating to patients quality of life, you don’t see the nausea, your hair doesn’t fall out,” he said.

Kaufman added that most patients can work and function relatively normally during treatment.