Breast cancer vaccine looks safe, study shows

By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - A vaccine designed to treat breast cancer appeared to be safe in women with advanced disease and showed signs of actually slowing down tumors, U.S. researchers reported on Friday.

Dendreon Corporation, maker of the Provenge prostate cancer vaccine, calls the new vaccine Neuvenge. It targets a type of breast cancer called her2/neu-positive breast cancer, which affects between 20 percent and 30 percent of breast cancer patients.

Like Provenge, Neuvenge is made using immune cells from the cancer patient, so it is a tailor-made vaccine.

Dr. John Park of the University of California, San Francisco and colleagues tested it in 18 women with advanced her2/neu-positive breast cancer, whose cancer had spread despite treatment.

Writing in the Journal of Clinical Oncology, the researchers said the vaccine did not cause any serious side effects and appeared to help at least one patient.

"We saw a partial response, meaning a reduction in the size of tumor area in one patient that was certainly attributable to the treatment," Park said in a telephone interview.

In three other women, their cancer appeared to stabilize for as long as a year, something that could have been due to treatment, Park said.

Park said the effects justify moving from the Phase 1 safety trial to a Phase 2 trial, which would be designed to show the treatment actually helps patients. But that may not happen for a while, he said.