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© NIH WASHINGTON (AFP) - The results of the study, which address changes in the IKZF1 gene, or IKAROS, and the relapse of acute lymphoblastic leukemia (ALL), should be used to form the basis of future diagnostic tests to determine the risk of treatment failure, the authors said.
ALL, a cancer of white blood cells, is the most common form of child cancer and affects one in 29,000 children annually. Cure rates for those afflicted with ALL are above 80 percent with current available therapies, but side effects are substantial and just 30 percent of children who suffer an ALL relapse will live five years.
"Great progress has been made in recent years in improving the cure rate of childhood ALL," said Stephen Hunger, chairman of the Children Oncology Group (COG) and the lead investigator on the study, conducted by scientists from the US National Institutes of Health and other facilities.
"The findings of this study help us further subdivide those patients who are unlikely to be cured, and identify patients in whom different therapies should be tested," Hunger added.
Physicians will be able to use a molecular test to identify the genetic marker in ALL patients and assign them to appropriate therapies, according to the study.
Its researchers analyzed the genetics data from leukemia cells in 221 children with high-risk leukemia who had already been treated in a COG study.
They used micro-arrays and DNA sequencing, which allow researchers to rapidly and efficiently analyze many genes in the same cell simultaneously, to identify genetic abnormalities in leukemia cells and then studied whether any of the genetic changes predicted relapse.
Scientists also examined a second group of 258 children with ALL who were treated at St. Jude Children's Research Hospital in Memphis, Tennessee.
The most significant findings related to the IKAROS gene, whose genetic mutations were shown to pinpoint a subgroup of patients who had a very poor prognosis.
The IKAROS gene has been shown to determine production of the IKAROS protein, which plays an essential role in development of lymphocites -- white blood cells whose mutations give rise to ALL.
The study found that patients with IKAROS alterations had "primitive, stem cell-like genes," suggesting they were more resistant to the effects of drugs used to treat ALL.
"These findings show how detailed analysis of leukemic cells using complementary techniques can enhance our understanding of the genetic basis of leukemia," said study co-author Cheryl Willman, director of the University of New Mexico Cancer Research and Treatment Center.
©AFP