Avastin slows progress of breast cancer in trial

CHICAGO (Reuters) - The addition of Genentech Inc's cancer drug Avastin to chemotherapy slows the progress of breast cancer at two different doses, according to results of a large international trial released on Saturday.

The trial showed that after 11 months, patients treated with a high dose of Avastin were 28 percent less likely to have their disease get worse compared with patients on chemotherapy alone. Those given a low dose of the drug were 21 percent less likely to have tumor growth compared to chemotherapy alone.

The results suggest that "the jury is still out" on whether a lower, and much less expensive, dose of Avastin would be an effective option for breast cancer patients, said Dr. Eric Winer, director of the oncology center at Dana-Faber Cancer Institute in Boston.

Dr. David Miles, of Mount Vernon Cancer Center in the United Kingdom and the study's lead investigator, said "the tendency is to think that the higher dose is best for our patients."

Avastin costs more than $4,000 a month at the low dose and double that for the high dose.

"The general message here is that Avastin has a role in breast cancer, but based on the scientific data it has not become the standard of care," Dr. Winer said.

Under U.S. Food and Drug Administration protocols -- which take into account differences in prognostic indicators and other changes -- the trial showed that progression-free survival was 39 percent better for patients on high-dose Avastin, and 31 percent better for the low-dose group, according to the researchers.

The results "were in-line with expectations. The fear was that the high dose would look inferior," said Eric Schmidt, an analyst at Cowen & Co.

The data "are likely to provide a tailwind to a launch that we believe will be above expectations," JP Morgan analyst Geoffrey Meacham said in a research note, referring to pending regulatory approval of Genentech's marketing materials.

Avastin, known chemically as bevacizumab, is already approved in the United States -- at the higher dose of 15 mg per kilogram and in combination with paclitaxel chemotherapy -- as an initial treatment for patients diagnosed with advanced breast cancer. U.S. sales totaled $2.3 billion last year.

The 736-patient trial presented at a meeting of the American Society of Clinical Oncology in Chicago involves treatment with another taxane chemotherapy agent, docetaxel, sold under the brand name Taxotere.

Taxotere is more commonly used in Europe, Asia and Australia, while U.S. oncologists are more likely to use paclitaxel, or Taxol.

Swiss drugmaker Roche Holding AG, which sells Avastin outside of the United States and holds a majority stake in Genentech, conducted the European trial.

"This is the second confirmation of efficacy in breast cancer patients," said David Schenkein, senior vice president of clinical hematology/oncology at Genentech.

He noted that the trial, which was not designed to compare the two doses of Avastin, is continuing and results of overall survival are expected late next year.

Early survival results, based on just 15 percent to 20 percent of patients, show that the high dose of Avastin plus chemotherapy improved survival by 47 percent compared to placebo plus chemotherapy, while the low dose of the drug raised survival by 9 percent, according to Schenkein.

Results at 11 months showed that breast cancer tumors shrank in 63.1 percent of patients on high-dose Avastin, 55.2 percent on low-dose Avastin and 44.4 percent in the placebo plus chemotherapy group.

Severe side effects, such as high blood pressure, were seen in 74.1 percent of patients in the high-dose group, 74.8 percent of the low-dose group and 67 percent of the chemotherapy-alone group.

Bowel perforations occurred in two patients in the placebo group and one patient in each of the Avastin groups.

Schenkein said there were no differences in the rate of severe side effects between the two doses.

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