New drug ambushes breast cancer

Doctors may have a new weapon in their arsenal against breast cancer, thanks to more than a decade of work by scientists and doctors in the Triangle.

GlaxoSmithKline reported Saturday that an experimental drug called Tykerb promises to delay tumor growth in women with advanced breast cancer for nearly twice as long as the current treatment.

"I don't know if this drug is a cure for cancer, but it's much better than the treatments we've got," said Kimberly Blackwell, an oncologist at Duke University Medical Center who has led trials to test Tykerb in patients.

The late-stage study tested Tykerb in women who had stopped receiving a benefit from Herceptin, a Genentech therapy that is considered one of the best treatments available for breast cancer. Tykerb targets aggressive breast cancer tumors that put out large amounts of a growth protein called HER2. While Herceptin battles HER2 cancer cells from the outside, Tykerb attacks from inside the cells.

Results showed that patients taking Tykerb in combination with Xeloda, an oral chemotherapy drug, went 8 1/2 months without having their tumors grow or spread to other parts of their bodies.

A group of patients who were treated only with Xeloda experienced a delay of 4 1/2 months, said Charles Geyer, director of breast medical oncology at Allegheny General Hospital in Pittsburgh and the principal investigator for the study.

The results were so promising that GSK ended the experiment early and offered Tykerb to the patients who were only getting Xeloda. The company plans to file for marketing approval for Tykerb in late-stage breast cancer by the end of the year.

A growing market

GSK's April announcement of the study's end -- before it had even finished recruiting patients -- caught doctors' attention, Blackwell said.

"Anytime a study is stopped early due to efficacy, this drug really works. We rarely see that in breast cancer," she said. "As an investigator, I knew this was going to be big."

And GSK is making a big splash with Tykerb, unveiling its latest clinical trial results on one of the most prominent stages in its industry, the American Society of Clinical Oncology's annual meeting.

The gathering, this year in Atlanta, is "the definitive meeting for the year in the oncology world" for companies, doctors and academic and clinical researchers, said Peter Cartwright, a financial analyst following health care companies for Williams de Broe, a brokerage company in London.

Over the past five years, GSK and most of its competitors have invested heavily in developing their own blockbusters for one of the industry's largest and fastest-growing markets. IMS Health projects that the market for cancer drugs, which measured about $15 billion in 1998, could hit $40 billion by 2008.

Tykerb is one of many drugs in development at GSK, but as part of the company's relatively new cancer portfolio, "there's quite a lot riding on it," Cartwright said.

Meanwhile, Tykerb's apparent success is also a win for a team of GSK biologists and chemists who have been working on the drug for more than a decade at the company's U.S. headquarters in Research Triangle Park.

But they haven't been laboring alone. Duke researchers and doctors have been involved in the development of the drug "since it was still known as 572016," Blackwell said, referring to the numeric label drug companies bestow on early candidates.

Several benefits

Geyer and GSK's head of oncology cast Tykerb and Herceptin as potentially complementary therapies in a conference call Thursday, but the practicalities of treating cancer mean that patients and doctors may look past Herceptin, which generated sales of $764 million last year, to Tykerb.

Tykerb has several benefits in addition to its effectiveness. Unlike Herceptin, GSK's new drug is taken by mouth, meaning patients potentially could be treated on an outpatient basis. What's more, Tykerb has shown little of the heart toxicity that concerns doctors about Herceptin, Blackwell said.

Tykerb also could be cheaper. It's made from small chemical molecules, which are usually less expensive to produce than a biological product like Herceptin, which is made from antibodies.

Breast International Group, a nonprofit clinical trials network, is proposing studies that will test the drugs together and sequentially and compare them head to head.

GSK also is testing Tykerb against several other types of cancer, including kidney and head and neck, as well as different forms and stages of breast cancer.

GSK scientists and their clinical investigators have 13 different presentations about Tykerb on the ASCO conference schedule, including one reporting results from a study of the drug in inflammatory breast cancer, which affects about 1 percent of patients. Blackwell was one of the main investigators in that study, which she said showed Tykerb to be "highly effective."

"There's so much going on with that drug," she said.