There have been over 200 clinical trials involving chemotherapy FOR DIPG patients, and none has shown any benefit. While this statistic is clearly disheartening, virtually all of these trials were designed before we knew much about the biology of DIPG tumors. Given that these studies were typically designed on the assumption that DIPG tumors would respond to similar treatments as adult glioblastomas, it is unsurprising that the results have been so poor. Doctors and researchers are optimistic that future clinical trials will be more successful because they can draw on the new research discussed above.
Based on the discovery of distinct subgroups of DIPG patients, some studies are being designed to provide individualized therapy to each DIPG patient based on the particular characteristics of his or her tumor. In these studies, the patient’s tumor is biopsied and genetic testing used to identify the specific mutations and other abnormalities in the tumor. This information guides the choice of chemotherapy agents to treat the tumor. While this general approach seems promising, its success will ultimately depend on the development of chemotherapy agents to address each type of mutation driving the development and progression of DIPG tumors.
Other studies are currently exploring whether DIPG patients can benefit from immunotherapy. Immunotherapy is a treatment that uses the body’s immune system to fight cancer cells. It has established itself as a promising treatment strategy for some types of cancer, and there are many studies currently trying to treat brain tumors using immunotherapy. This type of treatment recently received significant attention when 60 Minutes ran a story on a study at Duke University where the polio virus is injected into adults’ glioblastoma tumors to trigger an immune response. This study has shown great promise in using immunotherapy to treat glioblastoma, which has given hope that similar treatments will be developed for other types of brain tumors. Clinical trials using immunotherapy on DIPG patients are underway.
In addition to searching for more effective drugs, clinical trials are also trying to find new methods for administering those drugs to DIPG patients. Most patients have traditionally received chemotherapy either orally or intravenously. When these methods are used, the blood-brain barrier poses a significant obstacle to treatment. The blood-brain barrier protects the brain by preventing toxins and other molecules in the bloodstream from entering brain cells. In many brain tumors, the blood-brain barrier is compromised as the tumor grows, which allows drugs to reach the tumor more easily. But DIPG tumors typically do not seem to disrupt the barrier, making it difficult for drugs to reach the tumor. This is a significant issue for any new drug because the drug cannot be effective if it stays in the bloodstream and does not reach the tumor.
Investigational studies are currently being conducted in which medication is delivered directly into the tumor through a process known as convection enhanced delivery (CED). CED requires a catheter to be surgically placed into the tumor, which allows the medicine to bypass the blood-brain barrier. This delivery method is considerably more invasive than traditional methods of chemotherapy delivery chemotherapy, but initial studies have demonstrated the safety of this procedure. Further studies are necessary to continue to refine the process, as well as to try to identify drugs that can be effective when delivered this way.