Burkitt lymphoma gene expression signature identified

Jun 14 2006

An international research study involving the University of Nebraska Medical Center, the National Cancer Institute and 10 other institutions has successfully identified the gene expression signature for Burkitt lymphoma.

The discovery, which is reported in The New England of Medicine, will allow physicians to better diagnose and treat Burkitt lymphoma and better distinguish it from another more common form of malignant lymphoma.

Burkitt lymphoma is a rare aggressive B cell lymphoma that accounts for 30 to 50 percent of lymphomas in children but only 1 to 2 percent of lymphomas in adults. Burkitt lymphoma is rapidly fatal if untreated, but it is curable with intensive therapy.

Burkitt lymphoma features a high degree of proliferation of the malignant cells and deregulation of the c-myc gene, which is characteristic of Burkitt lymphoma. The distinction between Burkitt lymphoma and diffuse large B cell lymphoma (DLBCL), the most common form of non-Hodgkin's lymphoma in adults, is critical, because the management of these two diseases differs. About 300 new cases of Burkitt lymphoma, typically in children, are diagnosed in the U.S. each year.

Whereas a relatively low-dose chemotherapy regimen is typically used to treat DLBCL, this regimen is inadequate for Burkitt lymphoma, which requires intensive chemotherapy. In addition, because of the high risk of central nervous system involvement with Burkitt lymphoma, it is essential that intrathecal or systemic chemotherapy that crosses the blood-brain barrier be administered. This type of chemotherapy is unnecessary in most cases of DLBCL.

The article in The New England Journal of Medicine featured the results of two studies on the molecular diagnosis of Burkitt lymphoma involving several European and North American institutions. One of the research teams was led by Wing (John) Chan, M.D., the Amelia and Austin Vickery Professor of Pathology and co-director of the Center for Lymphoma and Leukemia Research at UNMC, and Louis Staudt, M.D., Ph.D., head of the molecular biology of lymphoid malignancies section at the National Cancer Institute. The research was supported through a multi-million dollar Director Challenge Grant awarded to Dr. Chan by the National Cancer Institute.

"Our group studied the gene expression profiles of 71 previous, untreated HIV-negative patients with sporadic Burkitt lymphoma or Burkitt-like lymphoma," said Kai Fu, M.D., Ph.D., assistant professor, pathology and microbiology, at UNMC and the second author of the study. "We successfully identified a gene expression signature for Burkitt lymphoma that clearly distinguishes Burkitt lymphoma from DLBCL."

Using the gene expression signature for Burkitt lymphoma, the group was readily able to distinguish Burkitt lymphoma from DLBCL by the high expression of the c-myc target gene as well as a subset of other target genes.

Overall survival was markedly superior for patients with a molecular diagnosis of Burkitt lymphoma, as they were given an intensive chemotherapy regimen instead of a lower dose regimen. Notably, eight cases given a pathological diagnosis of DLBCL were re-classified by gene expression as Burkitt lymphoma. These cases had all the gene expression hallmarks of Burkitt lymphoma, suggesting that they represent cases of Burkitt lymphoma that are difficult to diagnose by current methods.

The study results would suggest that gene expression profiling is an accurate, quantitative method to distinguish Burkitt lymphoma from DLBCL, Dr. Fu said. "This study gives us another example of the usefulness of gene expression profiling for defining biologic entities with important implications for clinical research and practice," he said.

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