HER2-positive breast cancers have too many copies of the HER2/neu gene. A study gave an experimental vaccine that targets the HER2/neu gene to mice. When the mice were later injected with HER2-positive cancer cells, their immune systems destroyed the cancer cells.
While this research shows promise, this study was done in mice, not people. Much more work needs to be done before a human vaccine is available.
About 25% to 30% of all breast cancers are HER2-positive. HER-positive breast cancers tend to be more aggressive than HER2-negative breast cancers. Herceptin (chemical name: trastuzumab) and Tykerb (chemical name: lapatinib) are targeted therapy medicines that treat HER2-positive advanced-stage breast cancers. Herceptin also is used to treat HER2-positive early-stage breast cancer after surgery to reduce the risk of the cancer coming back.
Still, many HER2-positive breast cancers either don't respond or stop responding to targeted therapies. This is one reason why doctors continue to look for better ways to treat HER2-positive breast cancer.
Vaccines train the immune system to react to a specific target by exposing the immune system to the target or a weakened version of the target.
The vaccine in this study targeted the HER2/neu gene and contained:
- a modified version of part of the HER2/neu gene
- particles that deliver the gene bits to the mouse immune system (called plasmids)
- substances that stimulate the immune system
When the mice immune systems responded to the vaccine, they made antibodies and T-cells. Antibodies and T-cells are special immune factors that seek out and destroy the targeted invaders. So when the mice were injected with HER2-positive cancer cells, their immune systems were ready to produce large amounts of antibodies and T-cells that attacked the cancer cells.
Another preliminary study showed that women being treated for HER2-positive breast cancer who also received an experimental HER2 cancer vaccine, called NeuVax, were more likely to be alive 2 1/2 years later compared to women who didn't get the vaccine.
In a sense, vaccines rev up your immune system so it better protects you against disease or is better at fighting any disease you already have. Much research still needs to be done, but there is hope that vaccines will be effective in both preventing and treating cancer, including breast cancer.
Stay tuned to Breastcancer.org for the most up-to-date news on vaccines and other new approaches to breast cancer prevention and treatment.