Investigators at Johns Hopkins have found a known genetic pathway to be active in many difficult-to-treat pediatric brain tumors called low-grade gliomas, potentially offering a new target for the treatment of these cancers.
In laboratory studies, researchers found that the pathway, called mammalian target of rapamycin (mTOR), was highly active in pediatric low-grade gliomas, and that mTOR activity could be blocked using an experimental drug, leading to decreased growth of these tumors.
"We think mTOR could function as an Achilles heel," says study co-author Eric Raabe, M.D., Ph.D., an assistant professor of pediatrics, oncology and pathology at the Johns Hopkins Kimmel Cancer Center. "It drives cancer growth, but when mTOR is inhibited, the tumor falls apart." The work was described Nov. 7 in the journal Neuro-Oncology.
Overall, brain tumors affect more than 4,000 children each year in the U.S., and they are the leading cause of cancer deaths in children, according to Raabe. Low-grade gliomas are the most common group of tumors of the central nervous system in children. Current treatments for these tumors include surgery and chemotherapy, which often cause significant side effects. Many of these tumors are located in areas like the optic pathway, where they can't be easily removed by surgery without causing damage, including blindness. In addition to vision loss, some of Raabe's patients have endured paralysis or learning problems as a result of the tumor or treatment. "Even though these tumors are considered 'low grade' and not particularly aggressive, many patients suffer severe, life-altering symptoms, so we desperately need better therapies," says Raabe.
For the study, the Johns Hopkins investigators studied tissue samples from 177 pediatric low-grade gliomas, including the most common type -- tumors called pilocytic astrocytomas -- from patients treated at Johns Hopkins and other centers. They also tested the
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Johns Hopkins Medicine