Researchers evaluate vaccines for combatting brain tumors
Ask Robert Aiken, MD, a neuro-oncologist at Rush, if he's optimistic about the future of treatments for brain cancers, and you'll get a resounding "yes."
"Just 15 years ago, we had limited options at our disposal when it came to combating these deadly diseases: surgery, radiation therapy and chemotherapy," Aiken says. "Today, there are several promising vaccines and novel drugs that, if approved by the Food and Drug Administration, could work with existing therapies to prolong survival."
Vaccine in clinical trials
Vaccines tap into the body's natural defense systems to combat disease. But unlike the chicken pox or flu vaccines, cancer vaccines aren't preventive; they go to work after the cancer develops.
One cancer vaccine for gliobastoma multiforme, or GBM — ICT-107 — is currently in phase II clinical trials at Rush, following an impressive showing in phase I trials. Phase I trials mostly assess address safety, while phase II studies take a closer look at a drug's effectiveness.
In the earlier studies, patients newly diagnosed with GBMs, received the vaccine as well as "standard of care" treatment (i.e., surgery, chemotherapy and radiation therapy). The results: 100 percent overall survival at one year (compared with 61.1 percent survival, historically, for those receiving just the standard of care) and 80 percent survival overall at two years (compared with 26.5 percent, historically, for those receiving just the standard of care).
Here's how the ICT-107 vaccine works: Doctors take dendritic cells, which are part of the body's immune system, from each patient's blood. Dendritic cells help introduce to the body's defense system antigens, molecules that kick-start the body's immune response.
Once investigators remove the dendritic cells from the patient, a process that personalizes the vaccine to each person, they load them up with human-made antigens similar to those found naturally on GBM cancer cells. Investigators then inject the end product, the vaccine, into the patient, thereby jumpstarting the body’s immune response against the GBM cancer cells. The goal is to kill the remaining GBM tumor cells after surgery and chemotherapy.
On the horizon
Similar to ICT-107, DCVax — which should be in clinical trials next month, says Aiken — is another personalized vaccine designed to create an immune response. Again, investigators use the patient's own dendritic cells.
But instead of working with human-made antigens, researchers extract GBM tumor cells from the patient and use those with the dendridtic cells to trigger the immune response. Because these dendridic cells have been "educated" to recognize and attack the patient's actual GBM tumor cells, the hope is that they'll be more effective in destroying them.
Also on the horizon are drugs designed to make radiation therapy more effective and small-molecule drugs designed to bypass the brain’s natural protective barriers to prevent recurrence of disease, Aiken says. The blood brain barrier — which only allows essential molecules such as amino acids, oxygen, glucose and water to access the brain — has been a major deterrent to finding effective drugs to treat brain cancer and other diseases of the brain.
Advances in technology also offer promise in providing gentler, more effective treatment options. For example, Rush recently began using TrueBeam STx, a powerful, noninvasive radiosurgery system, that destroys cancerous and benign tumors with high-dose, highly accurate radiation beams while minimizing damage to healthy tissue.