Public release date: 20-Jun-2012 [ | E-mail | Share ]

Contact: Summer Freeman summer.freeman@stjude.org 901-595-3061 St. Jude Children's Research Hospital

Researchers studying the genetic roots of the most common malignant childhood brain tumor have discovered missteps in three of the four subtypes of the cancer that involve genes already targeted for drug development.

The most significant gene alterations are linked to subtypes of medulloblastoma that currently have the best and worst prognosis. They were among 41 genes associated for the first time to medulloblastoma by the St. Jude Children's Research Hospital Washington University Pediatric Cancer Genome Project.

"This study provides new direction for understanding what drives these tumors and uncovers totally unexpected new drug targets. There are drugs already in development against these targets aimed at treating adult cancers and other diseases," said Richard Gilbertson, M.D., Ph.D., St. Jude Comprehensive Cancer Center director. Gilbertson and Jinghui Zhang, Ph.D., an associate member of the St. Jude Department of Computational Biology, are the study's corresponding authors. The work appears in the June 20 advance online issue of the scientific journal Nature.

The results mark progress toward more targeted therapies against medulloblastoma and other cancers. While better use of existing drugs and improved supportive care have helped push long-term survival rates for childhood cancer to about 80 percent, drug development efforts have largely stalled for more than two decades, particularly against pediatric brain tumors.

"This study is a great example of the way whole-genome sequencing of cancer patients allows us to dig deep into the biology of certain tumors and catch a glimpse of their Achilles heel," said co-author Richard K. Wilson, Ph.D., director of The Genome Institute at Washington University School of Medicine in St. Louis. "These results help us better understand the disease and, as a result, we will be able to more effectively diagnose and treat these kids."

This study involved sequencing the complete normal and cancer genomes of 37 young patients with medulloblastoma, making it the largest such effort to date involving the cancer. Researchers then checked tumors from an additional 56 patients for the same alterations. The genome is the complete set of instructions needed for human life. It is carried in the DNA found in nearly every cell.

The findings are part of the Pediatric Cancer Genome Project, which launched in 2010 as a three-year effort to decipher the complete normal and tumor genomes of 600 young cancer patients with some of the most challenging tumors. The endeavor has already yielded important clues into the origin, spread and treatment response in childhood cancers of the blood, brain, eye and nervous system.

Medulloblastoma is diagnosed in about 400 U.S. children and adolescents annually. Their outcome varies widely based on the subtype they have. While nearly all patients with the wingless (WNT) subtype survive, just 60 percent of those with subtype 3 medulloblastoma are alive three years after diagnosis. WNT medulloblastoma is named for the pathway disrupted in the tumor subtype.

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Gene sequencing project identifies potential drug targets in common childhood brain tumor