Glioblastoma, also known as grade IV glioma, is the most aggressive primary brain tumor in humans. Approximately 23,000 people in the U.S. are diagnosed with glioblastoma (GBM) every year. Patients usually receive surgery, chemotherapy and radiation, but these treatments are not very effective as an estimated 50 percent of GBM patients die within one year, and 90 percent die within three years.
A study led by UCLA’s Drs. Robert Prins and Linda Liau, both UCLA Jonsson Comprehensive Cancer Center members, looked at the impact of a combined treatment using a chemotherapy drug called decitabine and genetically modified immune cells or T cell immunotherapy. It is a continuation of previous research, published in 2011, that focused on the effect of decitabine on glioblastoma human cell cultures.
In the new research, Prins and Liau used a technique called adoptive cell transfer, which involves extracting and growing immune cells outside of the body, then reprogramming them with a gene known as New York Esophageal Squamous Cell Carcinoma, or NY-ESO-1. They are then injected back into tumor-bearing mouse models to produce an immune response that targets the brain cancer.
Glioblastoma cells do not naturally produce NY-ESO-1, so the drug decitabine is given prior to injecting the NY-ESO-1 targeting T cells in order to cause the tumor cells to express the NY-ESO-1 target.
“The lymphocytes will seek out and find the glioblastoma cells in the brain,” said Prins, associate professor in the departments of neurosurgery and molecular and medical pharmacology. “They can cross different fiber tracts in the brain to reach tumor cells that have migrated away from the main tumor mass. These factors are important in the treatment of invasive tumors, such as glioblastoma. While surgery to remove the main tumor mass can be done, it is not possible to then locate the tumor cells that get away and this ultimately leads to a nearly universal tumor regrowth.”
This new method was nearly 50 percent effective at curing glioblastoma in the study.
“Brain cancer cells are very good at evading the host immune system, because they do not express specific targets that can be recognized by immune cells,” said Liau, professor and vice chair of neurosurgery. “By treating glioblastoma cells with decitabine, we found that we can unmask targets on the tumor cell that can be recognized by killer T cells. Once these targets are uncovered, we can then administer T cells that are genetically programmed to attack tumor cells with the new targets.”
The next stage of research conducted by Prins and Liau will verify these findings in other brain tumor models. If the results are promising, then the researchers will proceed with clinical trial testing.
This research was published in the journal Neuro-Oncology on Sept. 1.