June 3, 2006

Glaxo drug slows breast cancer in study

By Lisa Richwine

ATLANTA (Reuters) - An experimental drug added to
chemotherapy slowed aggressive, late-stage breast cancers that
resumed growing despite standard treatment with the drug
Herceptin, U.S. researchers said on Saturday.

The drug, Tykerb, by GlaxoSmithKline Plc, also showed
potential to help some patients with advanced kidney cancer,
another study showed.

Glaxo hopes to begin selling the drug next year, but must
await regulatory approval. Industry analysts predict it could
become a multi-billion-dollar seller.

A Glaxo-sponsored study of 321 women showed breast cancer
did not progress for an average of 37 weeks in patients treated
with Tykerb and oral chemotherapy drug Xeloda, compared with 20
weeks for others who received only Xeloda.

The findings were so striking that researchers halted the
study early.

All of the women were treated previously with Herceptin, a
drug that fights the 20 percent to 25 percent of breast cancers
that produce large amounts of a protein called HER-2. Herceptin
works for a time, but the cancer eventually grows.

Tykerb, if approved for sale, could offer hope to women
whose cancers return after they were successfully beaten back
by Herceptin, said Dr. Charles Geyer, director of breast
medical oncology at Allegheny General Hospital in Pittsburgh
and the study's lead author.

"The ability to control cancer growth a second time on this
order of magnitude ... is really quite substantial for a
patient," Geyer said.

The findings were released at an annual meeting of the
American Society of Clinical Oncology.

Xeloda, known generically as capecitabine, is sold by Roche
AG, which also sells Herceptin along with Genentech Inc..
Tykerb's generic name is lapatinib.

Glaxo is testing if Tykerb works earlier in breast cancer.
As a pill it could be a convenient alternative to Herceptin,
which must be injected. Herceptin's annual sales are about $1.8

Dr. Pamela Klein, Genentech vice president for oncology and
hematology, said doctors would continue to prescribe Herceptin
widely given its track record in extending survival.

"I think Herceptin is not going to be given up right now,"
she said.


Future research may give Tykerb an advantage over Herceptin
for some but not all patients, said Dr. Julie Gralow, a breast
cancer specialist at the University of Washington in Seattle.

An estimated 215,000 cases of breast cancer are expected to
be diagnosed in the United States this year, and about 41,000
women are projected to die from the disease, according to the
American Cancer Society.

Tykerb targets the HER2 protein as well as another known as
EGFR that is involved in tumor growth.

Geyer said no Tykerb patients in the breast cancer study
developed symptoms of congestive heart failure, a serious
potential side effect from Herceptin. Women who took Tykerb
were more likely to experience diarrhea and rashes than others
who got only Xeloda.

In a separate study, Tykerb failed to improve overall
survival in a trial of 416 patients with advanced kidney
cancer. Benefits were seen, however, in 241 of those who had
tumors that produced the highest EGFR amounts. Patients in that
group who took Tykerb survived an average of 46 weeks, compared
with 38 weeks for standard hormonal therapy.