Could a vaccine prevent breast cancer?
New research is showing promise that a vaccine may be able to fight one type of the most common cancers in women.
Phase one clinical trials examined immune response to a new breast cancer vaccine by measuring antibodies in white blood cells. Researchers hope the vaccine could eventually prevent and treat breast cancer that affects 1 in 8 women.
“The trial looked primarily at patients with triple negative (estrogen receptor negative, progesterone receptor negative, HER2 negative) breast cancer and showed a 75% immune response,” says Dr. Chirag Shah, Division Chair of the Department of Radiation Oncology with Allegheny Health Network (AHN).
Phase one of the trial saw 35 women – most of whom had triple negative breast cancer – get the test vaccine and undergo blood testing to measure antibodies against alpha-lactalbumin.
“That molecule, α-Lactalbumin (aLA), is expressed in lactating breasts and in 70% of triple-negative breast cancer (TNBC) cases but not at other times or in other tissues,” said Shah. “The protein is no longer found after lactation in normal, aging breast tissues but is present in most triple-negative breast cancers. If breast cancer develops, the vaccine is designed to prompt the immune system to attack the tumor and keep it from growing.”
If proven to be successful, the vaccine eventually could be used not only to target existing TNBC tumors but also to help prevent it by alerting the body that the protein is being produced and to create antibodies to destroy it. Previous research done on mice has shown the vaccine can activate the immune system to prevent such tumors from forming.
Three-phase study
The Cleveland Clinic is working to develop the TNBC vaccine, and the first part of the trial involved patients getting a set of three shots spaced out by two weeks. The study is made up of three planned phases. Phase IA includes patients who completed treatment for early-stage, triple-negative breast cancer within the past three years and are currently tumor-free but at high risk for recurrence.
“Phase IB includes individuals who are cancer-free and at high risk for developing breast cancer who have elected to voluntarily have a preventive mastectomy to lower their risk,” said Shah. “Primarily, these are women with BRCA1, BRCA2, and PALB2 mutations.”
Phase IC will include patients with early-stage triple-negative breast cancer who have received preoperative chemoimmunotherapy and surgery and are being treated with pembrolizumab following surgery. These patients have residual cancer in the breast tissue, making them at risk of recurrence.
Beyond this trial, there are other studies underway evaluating vaccine or immunologic approaches for breast cancer and other malignancies.
“These trials are promising, but there is still significant work to do,” Shah said. “Also, work is needed for other types of breast cancer beyond triple negative breast cancer. Overall, to date the trials have shown promising safety profiles as well.”
What makes creating a cancer vaccine so challenging is that tumors grow out of an individual’s own cells. That makes them unique as opposed to vaccines that target organisms like a certain strain of flu virus, smallpox or measles.
Other breast cancer vaccine trials are also being conducted that would work toward treating and preventing different types of the disease. Some vaccine research is targeting specific mutations in patients’ tumors and others are working on identifying and targeting proteins in breast cancer cells. In addition to the triple negative breast cancer (TNBC) vaccine, other trials underway include a vaccine targeting the HER2 protein that some cancerous tumors produce. Another area of research and vaccine trials is focused on tailoring a vaccine for an individual patient’s tumor by identifying unique mutations in the cancer cells and targeting those with the vaccine.