SAN ANTONIO — A novel anti-HER2 breast cancer vaccine reduced recurrences by 50% in a phase II clinical trial involving high-risk patients, Col. George E. Peoples, MC, USA, said at a breast cancer symposium sponsored by the Cancer Therapy and Research Center.
Based on these encouraging results, a large phase III randomized trial is planned, added Dr. Peoples, a surgeon at Brooke Army Medical Center, San Antonio.
The vaccine, called NeuVax, is built on the E75 peptide from the extracellular domain of human epidermal growth factor 2 (HER2), the oncogene targeted by trastuzumab (Herceptin). HER2 is overexpressed in one-quarter of breast cancers.
Other attempts at developing peptide vaccines for breast cancer have proved largely disappointing.
However, those vaccines were designed to treat metastatic disease. In contrast, the new E75 vaccine is a preventive therapy for patients who have been treated for breast cancer and have a high risk of recurrence but no evidence of breast cancer following multimodal treatment. The mechanism of action involves overcoming tolerance through repeated administration of large quantities of a single purified antigen.
Dr. Peoples reported on 101 patients who received monthly intradermal injections of the vaccine mixed with granulocyte-macrophage colony-stimulating factor and 85 controls who did not. All participants had lymph node-positive, HER2-positive breast cancer or high-recurrence-risk, node-negative, HER2-positive cancer and no evidence of disease.
At 20 months the recurrence rate was 5.7% in the vaccine group and 14.1% in controls.
At the latest update at 24 months, 8.3% of the vaccine group had developed recurrent disease, compared with 16% of controls, a difference that just missed statistical significance because of the small sample size, according to the surgeon.
Mild cutaneous, delayed-type hypersensitivity reactions to the vaccine were extremely common. There was no significant systemic toxicity.
The vaccine project was initially sponsored by the Department of Defense and conducted through the Uniformed Services University of the Health Sciences Cancer Vaccine Development Laboratory, Bethesda, Md. It has been taken over by Apthera, which is also developing the drug as a prostate cancer vaccine.