Results of a clinical trial of a breast cancer vaccine showed that, when women who had breast cancer were vaccinated, the cancer came back less often.
The researchers also found that the vaccine was safe and well-tolerated in patients.
"Ask your primary care physician about screening for breast cancer."
Even with treatment, breast cancer returns in about 20 percent of cases.
Targeting proteins on tumor cells has been the objective of drug therapy and vaccine development. One such protein is HER2. Trastuzumab (brand name Herceptin) is a type of immunotherapy medicine known as a monoclonal antibody that was developed to target HER2, a protein found in abundance in some breast cancers.
Elizabeth Mittendorf, MD, PhD, from the M.D. Anderson Cancer Center, led a clinical trial of a new vaccine against GP2, a protein on tumor cells.
Vaccines work differently than chemotherapy or immunotherapy. They do not kill cancer cells directly. The GP2 vaccine was developed to prime the immune system to look for the recurrence of any HER2 protein and destroy it.
Dr. Mittendorf presented her team's research results Sept. 6 at the 2014 American Society of Clinical Oncology’s Breast Cancer Symposium in San Francisco.
The researchers gave 89 breast cancer patients the vaccine combined with an agent to increase its effectiveness by stimulating the immune system (GM-CSF). Ninety-one women were given the GM-CSF alone.
All the women in the study had HER2 protein on their breast tumors in different amounts.
The patients received injections once a month for six months. From 12 to 36 months, they received boosters every six months. The researchers collected data on the women for up to five years.
The main goal of this Phase II study was to find out if the vaccine was safe. The vaccine was found to be as safe as the GM-CSF alone. The women also tolerated the vaccine well.
The researchers found that breast cancer recurrence decreased by 57 percent in women who got the GP2 vaccine, compared to those who received GM-CSF alone.
Some of the women in the study had also been previously treated with trastuzumab. In this smaller group of women, those who also received the vaccine did not experience a recurrence of their breast cancer during the study.
“This is an important and different avenue in immunotherapy research, in that we are investigating ways to prevent cancer recurrence by stimulating the immune system to treat cancer,” Dr. Mittendorf said in a press release.
Galena Biopharma, Antigen Express and Norwell sponsored the clinical trials. M.D. Anderson receives funds when patients are enrolled in the studies.
George Peoples, MD, a study author, had inventor rights to the GP2 vaccine.