Gene sequencing project discovers mutations tied to deadly brain tumors in young children

PUBLIC RELEASE DATE:

6-Apr-2014

Contact: Carrie Strehlau carrie.strehau@stjude.org 901-595-2295 St. Jude Children's Research Hospital

(MEMPHIS, TENN. - April 6, 2014) The St. Jude Children's Research Hospital-Washington University Pediatric Cancer Genome Project has identified new mutations in pediatric brain tumors known as high-grade gliomas (HGGs), which most often occur in the youngest patients. The research appears today as an advance online publication in the scientific journal Nature Genetics.

The discoveries stem from the most comprehensive effort yet to identify the genetic missteps driving these deadly tumors. The results provide desperately needed drug development leads, particularly for agents that target the underlying mutations. This and other studies show these mutations often differ based on patient age. HGGs represent 15 to 20 percent of brain and spinal tumors in children. Despite aggressive therapy with surgery, radiation and chemotherapy, long-term survival for HGG patients remains less than 20 percent.

The study is one of four being published simultaneously in the same issue of Nature Genetics that link recurring mutations in ACVR1 to cancer for the first time. Pediatric Cancer Genome Project researchers found that ACVR1 was mutated in 32 percent of 57 patients diagnosed with a subtype of HGG called diffuse intrinsic pontine glioma (DIPG). While DIPGs are usually found in children ages 5 to 10, ACVR1 mutations occurred most frequently in younger-than-average patients. DIPG occurs in the brainstem, which controls vital functions and cannot be surgically removed.

The investigators also identified alteration in NTRK genes that drove tumor development in young HGG patients whose tumors developed outside the brainstem. This study included 10 patients who were age 3 or younger when they were diagnosed with such non-brainstem HGGs. Of those, 40 percent had tumors with alterations in one of three NTRK genes and few other changes. The alterations occurred when a segment of the NTRK genes involved in regulating cell division fused with part of another gene.

"These results indicate the NTRK fusion genes might be very potent drivers of cancer development that have the ability to generate tumors with few other mutations," said co-corresponding author Suzanne Baker, Ph.D., a member of the St. Jude Department of Developmental Neurobiology. The other corresponding author is Jinghui Zhang, Ph.D., a member of the St. Jude Department of Computational Biology. "We want to see if these tumors might be selectively sensitive to therapies that target the pathways that are disrupted as a result of these fusion genes," Baker said.

Added co-author Richard K. Wilson, Ph.D., director of The Genome Institute at Washington University School of Medicine in St. Louis: "We've made some very exciting discoveries that likely will result in more effective diagnosis and treatment of these particularly nasty tumors."

In this study, researchers analyzed 127 HGGs from 118 pediatric patients, including whole genome sequencing of the complete tumor and normal DNA from 42 patients. More targeted sequencing of additional tumors was conducted to track how instructions encoded in DNA were translated into the proteins that do the work of cells.

Original post:
Gene sequencing project discovers mutations tied to deadly brain tumors in young children