Genetic Testing Offers New Hope for Children with Brain Cancer
More than half of pediatric cancer patients have genetic faults that could affect their diagnosis or be targeted by drugs.
In the past 30 years, childhood deaths from cancer have declined by 50 percent overall, but those from pediatric brain cancer have only decreased by 30 percent.
Researchers at the Dana-Farber Cancer Institute and Boston Children’s Hospital think precision medicine, the idea that treatments can be customized to individuals based on their genetics and other health information, could help improve those rates.
Investigators conducted genetic testing on 203 patient tumor samples and found that 56 percent of them harbored genetic abnormalities that could either help doctors diagnose or treat the brain tumor with drugs that are already available or those being studied in clinical trials.
The findings of their study, published in the journal Neuro-Oncology last week, also highlight key genetic differences in pediatric brain tumors compared to adult ones, suggesting that brain tumors in children and adults need to be treated differently.
Currently, such cancer genomic tests aren’t routine. They’re not covered by many health insurance plans or common outside research hospitals.
“The reason why we’re doing this for kids with brain tumors is that we’re not winning with standard treatments,” says co-lead study author Pratiti Bandopadhayay, a pediatric neuro-oncologist at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center. Pediatric brain tumors are the leading cause of childhood deaths from cancer. Surgery, radiation, and chemotherapy have been the standard treatments.
For decades, every child with the same tumor type received the same treatment, says Bandopadhayay. “We’re learning that when you look at these tumors under the microscope, even if they look the same, they might have different genetic drivers.”
While more cancer therapies that target specific genetic differences in tumors are coming onto the market, there are no FDA-approved targeted cancer drugs specifically for pediatric brain tumors.
One of the most common genetic mutations found among the 203 tumor samples was in the BRAF gene, which, when mutated, has the potential to cause normal cells to become cancerous ones. Two drugs for melanoma that target BRAF have been approved by the U.S. Food and Drug Administration. One of those, dabrafenib, is currently being tested in clinical trials for some types of pediatric brain tumors.
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Targeted therapies are likely to be most effective when they're matched to specific abnormalities within tumor cells. But Ann Kingston, director of research and scientific policy at the National Brain Tumor Society, who was not involved in the Dana-Farber study, says even people with the same genetic mutations in their tumors might not respond similarly to the same treatment.
She also says tumor samples may not always be representative of the entire tumor. For example, a genetic mutation might be found in some cells of the tumor but not in others. That could affect what drugs patients are prescribed.
The study didn’t track the outcome of the patients after their treatments. One of the uncertainties of precision medicine is whether these genomic tests lead to any improvements in life expectancy or quality of life for patients.
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