GSK drug could work on early-stage cancers

New test results suggest that a GlaxoSmithKline drug awaiting regulatory approval to treat late-stage breast cancer also has potential to corral the disease early on, before tumors spread.

Scientists who studied Tykerb in women unresponsive to other therapies concluded that the GSK treatment shows promise as an early-stage tumor buster. GSK controlled the study and paid for it.

Outcomes of the study, which was halted early because results in patients with late-stage breast cancer were so promising, were published last week in the New England Journal of Medicine.

Early GSK research on Tykerb indicated that the drug could be a powerful cancer treatment with few side effects, said Dr. Neil Spector, a cancer drug researcher who oversaw the drug's clinical testing before joining Duke University last year.

"This is great," Spector said of the conclusions. "The good news is there's so much interest. Everybody is moving very quickly in what will be a much more rapid development."

Scientists associated with Harvard Medical School began a clinical trial last summer to study Tykerb in early-stage breast cancer.

The conclusions from the GSK study "accelerate and reaffirm our expectations with Tykerb," said Dr. Paul Goss, a professor of medicine at Harvard and the director of the breast cancer program at Massachusetts General Hospital Cancer Center in Boston.

Goss and his colleagues control the study but GSK is paying for it. Results are expected in 2009 or 2010.

GSK plans to use the study's results to broaden regulatory approval for Tykerb, which will determine how many more patients could receive the pill and how much more in sales the drug could generate.

Analysts already project that the drug will become a blockbuster, exceeding $1 billion in annual sales by 2010.

About 210,000 cases of breast cancer are diagnosed in the United States every year, according to the American Cancer Society. In about 90 percent of the diagnoses, the cancer is in an early stage.

Tykerb, which was discovered by GSK scientists in the Triangle, targets a family of cancers that includes HER2-positive breast cancer. The name comes from a protein inside the cell, called HER2.

HER2-positive breast cancer uses this protein to make the cell resistant to death. As a result, the cell starts dividing rapidly. About one-third of all breast cancers are HER2-positive.

GSK is also investigating Tykerb as a possible treatment for head and neck cancers.

Chemotherapy doesn't work well on HER2-positive breast cancer. The best medicine available is Herceptin, a drug made by Genentech.

Herceptin was projected to generate about $1 billion in sales in 2006. But Herceptin must be given intravenously and has been shown to cause heart damage in 15 percent to 20 percent of patients.

Because it seems to delay tumor growth at least twice as long, has fewer side effects and can be taken orally, Tykerb has the potential to be superior to Herceptin, Goss said.