A gene that spurs colon cancer growth might offer a new target for drug treatments, Harvard University scientists said today in the journal Nature.

Better treatments are needed for colon cancer, which will kill about 49,000 people in the U.S. this year, said William Hahn, the study leader and an associate professor of medicine at the Harvard-affiliated Dana Farber Cancer Institute. The newly found gene controls a cell growth switch that may play a role in many tumors, Hahn said.

"It's likely to be important for about 35 to 50 percent of patients with colon cancer," Hahn said Sept. 12 in a telephone interview. "It's a very promising target."

The CDK8 gene makes an enzyme, called a kinase, which helps control the processes of division and replication. Kinases are targeted by a number of marketed cancer drugs, including Genentech Inc.'s Tarceva, AstraZeneca Plc's Iressa, and Celgene Corp.'s Revlimid.

CDK8 is one of at least 11 genes that make cyclin-dependent kinases. The enzymes they make combine with proteins called cyclins, a vital player in abnormal cell growth.

Several companies are already testing drugs that block other cyclin dependent kinases, and about 113 drugs are in testing, said Janice Reichert, a senior research fellow at the Tufts Center for the Study of Drug Development in Boston.

"There's a definite unmet medical need in colon cancer," she said. "And kinases do seem amenable to targeting with drugs."

About 26 percent of kinases that have entered human studies has gained U.S. approval, compared with about 8 percent of drugs overall, she said. Several companies have expressed interest in developing inhibitors of CDK8 as a drug, said Hahn, who declined to name the companies.