Training the immune system to fight cancer
The potential to harness the body's immune system to fight cancer may finally prove itself on a large scale in the next couple of years. Scores of new immunotherapy vaccines and other immune system modifiers are being tested against a variety of cancers. At least a dozen therapies are set to have key late- or mid-stage trial data.
The concept of using the immune system against cancer dates back to the 1890s when Dr. William Coley, a New York surgeon, noted that some patients who got infections after cancer surgery fared better. He surmised that the immune response triggered by the infection was also working to eradicate cancer.
According to Dr. Glenn Dranoff, co-director of the Dana-Farber Cancer Vaccine Center in Boston, although the idea of a vaccine or cancer immunotherapy has been around really for at least 100 years, we now know a lot more about what are the requirements to generate an effective anti-cancer immune response than we ever did.
Researchers had previously believed that only melanoma and kidney cancer had the right properties to respond to immune system therapy. They were eventually proven wrong. Clinical trials now are taking on lung, breast, liver, prostate, pancreatic, ovarian, head and neck and brain cancers.
The basic idea remains the same: train a patient's immune system to attack the cancer. But new approaches based on more recent knowledge of the immune system's components include activating a variety of cells to go after tumors and modifying mechanisms that keep either the immune system in check or turn it loose.
There appears to be near universal agreement that to achieve optimal benefit, immunotherapies should be combined with targeted cancer drugs or other immunotherapies in a multi-pronged attack.
According to the researchers at Anderson, our immune cells are like little tanks that travel round the body to shoot bacteria and viruses that are hurting us, but you can't let them go unregulated. When the body has cancer you want the tanks to go a little bit wild, so they want to lift those brakes and let them go after the enemy.
Some believe that companies would do well to test immunotherapies at an earlier stage of the disease, perhaps to prevent recurrence. Such trials take years longer to produce results, so companies tend to start trials with advanced cancer patients with limited life expectancy that yield results sooner.
The body's immune system is constantly trying to keep tumors from forming or coming back. If you can give the immune system a boost in terms of helping out with that long-term surveillance, it could make more sense biologically.
The immune system may take some months to ratchet up its anti-cancer armaments researchers say, so giving immunotherapy to a patient with just a few months to live may be futile.
Early disappointment in the field may have been due to testing on patients with very advanced disease whose immune systems were severely compromised by chemotherapyterm and radiation, and such failures are to be expected.