The results were published inJAMA Oncologythis month.
Existing treatments for HER2-positive breast cancer, includingmonoclonal antibodies and chemotherapy, can be unsafe or ineffective.
Some treatments must be given frequently for a long time.
According to the American Cancer Society, about 14% of people with breast cancer are HER2-positive.
Breast cancer cells with high levels of HER2 tend to grow and spread faster than HER2-negative breast cancers.
Over 80% of the participants who received the medium-dose vaccine were still living a decade later.
And 40% of those patients never had a recurrence.
Cancer vaccines are extremely safe.
They dont have any of the side effects of other standard treatments for cancer, Gillanders said.
How the Vaccine Works
The study included 66 patients who were treated between 2001 and 2010.
Researchers administered the vaccine intradermally once a month for three months.
The cells in the arm absorb that DNA and start pumping out copies of HER2.
The immune system recognizes the protein as foreign and dangerous and creates defense mechanisms against it.
The vaccine helps the immune system detect and destroy any remaining cellshelping prevent recurrence of the cancer.
Those who got the highest dosage of vaccine tended to have the most lasting immune response.
However, those who got the second-highest dose were more likely to survive in the decade after being immunized.
When including those with stage IV cancer, about 80% survived, Disis said.
Most of the study participants had previously been treated withtrastuzumabor were currently on the chemotherapy infusion medication.
The results show the vaccine is very safe.
These include monoclonal antibodies, including Herceptin and other biosimilar versions of trastuzumab.
Antibody-drug conjugates help chemotherapy drugs to attack cancer cells.
And kinase inhibitors stop the proteins like HER2 from relaying messages that allow cancer cells to grow.
There are some cancers where chemotherapy never worked.
Disis said her teams vaccine is now being tested in a Phase II clinical trial.
The trial will likely take about three years to complete.
Depending on the success of that trial, the vaccine will then be tested in a Phase III trial.
2021;22(2):779. doi:10.3390/ijms22020779
