Old drug, new trick

From Atlanta, at a meeting of the American Society of Hematology

A team of researchers has plucked the first fruit of what the group’s leader calls a “new approach to drug discovery.” Scott A.

Armstrong of Children’s Hospital and the Dana-Farber Cancer Institute in Boston and his colleagues found that the drug rapamycin, in combination with standard chemotherapy for acute lymphoblastic leukemia (ALL), can kill chemotherapy-resistant cells.

Rapamycin is used to prevent rejection in transplant recipients. ALL is often treated with the steroid prednisone, but it’s sometimes resistant to that medicine.

Armstrong’s team found that rapamycin decreases the activity of a key gene in steroid-resistant cells, making them susceptible to treatment.

The tip that rapamycin might work came from Todd R. Golub and his colleagues at the Broad Institute in Boston. Golub’s group is developing a database of how each Food and Drug Administration–approved drug affects the activity, or expression, of about 22,000 human genes.

Researchers already know how gene expression changes in many forms of cancer. By comparing the information on a particular cancer with the gene-expression effects of the entire medical armamentarium, they can potentially identify new therapeutic pairings, Armstrong says.

The concept, he says, is to “let the tumors and drugs tell us which ones should be matched.”

Already, Golub has catalogued several hundred drugs besides rapamycin. He aims to complete the task by mid-2007.

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