Dendreon Corp. (Nasdaq: DNDN) said its breast cancer vaccine Neuvenge appeared to be safe, according to results of an initial study.

Neuvenge is an investigational active cellular immunotherapy, which works by stimulating the immune system to fight disease.

The vaccine is meant for women with her2/neu-positive breast cancer who have failed standard therapy, a type of breast cancer which appears in 30 percent of all breast cancer patients.

In a statement released by Dendreon, the lead author of the study, Dr. John Park, M.D. of the University of California, San Francisco, said the vaccine was safe and well tolerated.

The findings warrant additional studies of Neuvenge for the many women with advanced breast cancer who have exhausted many of their treatment options, Dr. Park said.

He said the T-cell responses in the patients and prolonged disease stabilization is promising.

The study involved 18 patients. Twenty-two percent of patients had evidence of anti-cancer activity.

Dendreon's primary product in the development pipeline is a prostate cancer drug called Provenge, which is currently in the final stages of clinical trials. It has been delayed for approval by U.S. regulators who are requesting more proof that it can help patients live longer.

Dendreon said it was pleased with the results the Neuvenge study together with previous results from earlier Provenge studies, further substantiate the promise of active cellular immunotherapies as new treatments for different types of cancer.