Vaccines to prevent breast cancer from occurring, recurring or spreading are being studied in clinical trials across the U.S. and we are shining a spotlight on a few that are focused on these vaccines. This new, exciting area of research has the potential to advance care for people who are at high risk of breast cancer, as well as those diagnosed with the disease.
Outside of breast cancer care, there are proven vaccines to help the body’s immune system fight things we can think of as “intruders,” like viruses. These vaccines teach the immune system to spot an intruder and respond by either blocking it or preventing it from causing serious problems.
Breast cancer occurs when cells in the breast divide and grow without their normal control. This excess growth can form a tumor. Breast cancer researchers are investigating whether preventive vaccines can teach the immune system to recognize cells that could develop into breast cancer and stop them from growing (also called an immune response).
Below, you’ll learn more about two clinical trials that are studying preventive vaccines in the breast cancer space.
Triple Negative Breast Cancer Vaccine Study
This phase 1 study is testing the safety and the effective dose of a vaccine targeting a protein, a-lactalbumin. This protein is only made during lactation (the production of breast milk). It’s been found in some triple negative breast cancer (TNBC) cells. TNBC is breast cancer that is estrogen receptor-negative, progesterone receptor-negative and HER2-negative.
Researchers at the Cleveland Clinic are testing this vaccine to see if the immune system can recognize cancer cells and produce an immune response by destroying them before they grow into a tumor.
Participants are divided into three different groups:
- Group 1 has patients who completed treatment for early-stage TNBC within the past three years and are currently tumor-free, but at high risk for recurrence (cancer coming back).
- Group 2 includes people who are cancer-free and at a high risk of breast cancer who have elected to have a preventive (or risk-reducing) mastectomy to lower their risk. Primarily, these are women with BRCA1, BRCA2 and PALB2 inherited gene mutations.
- Group 3 has patients with early-stage TNBC who have received neoadjuvant (before surgery) chemotherapy and immunotherapy, then surgery, and are being treated with immunotherapy again after surgery. These patients have residual cancer (cancer cells that remain) in the breast tissue, making them at high risk of recurrence.
In Nov. 2024, researchers released hopeful findings from this study showing the vaccine was generally well tolerated and produced an immune response in most of the patients enrolled in the clinical trial.
This year, the clinical trial is expected to move to a phase 2 study that will test the effectiveness of the vaccine.
What this means for patients:
TNBC is often an aggressive breast cancer. Early-stage TNBC is more likely to recur within the first five years after a diagnosis when compared to early-stage estrogen receptor-positive breast cancers. One hope is the vaccine could be a new way to control TNBC.
“Long term, we are hoping that this can be a true preventive vaccine that would be administered to individuals who are cancer-free to prevent them from developing this highly aggressive disease,” said G. Thomas Budd, M.D., of Cleveland Clinic’s Cancer Institute and principal investigator of the phase 1 study.
Ductal Carcinoma in Situ Vaccine Study
Breast cancer cells express an abnormal form of a protein called MUC1 that can be recognized by the immune system as “foreign.” This phase 1 study is testing the safety of a vaccine that contains the abnormal protein to prime the immune system to mount an attack against the tumor.
Researchers at the University of Pittsburgh Medical Center are testing the vaccine in postmenopausal women who are newly diagnosed with ductal carcinoma in situ (DCIS). DCIS is a non-invasive breast cancer in which the cancer cells are contained in the milk ducts and have not invaded nearby breast tissue.
There are two groups of women in this clinical trial:
- One group will receive an aromatase inhibitor (hormone therapy) for 12 weeks prior to surgery and any other standard care they need.
- The other group will receive an aromatase inhibitor and this investigational vaccine. The vaccine is given at the time of enrollment in the study, again at 2 weeks and then 10 weeks later. At 12 weeks, participants move on to surgery and the other standard care they need. They may also receive an optional booster vaccine six months after surgery.
Researchers on a team led by Olivera Finn, PhD will be measuring how well the vaccine works to mount an immune response against MUC1 and the tolerability of the vaccine.
What this means for patients:
If left untreated, DCIS could progress to invasive breast cancer over time. Invasive breast cancer occurs when the cancer cells from inside the milk ducts or lobules break out into nearby breast tissue. It’s estimated that 10%-50% of DCIS cases may progress to invasive breast cancer. One hope is the vaccine would teach the immune system to recognize the precancerous cells in DCIS, then produce an immune response by fighting and destroying these cells to prevent them from becoming invasive.
Turning the Hope of Breast Cancer Vaccines into Reality
While promising, breast cancer vaccines are still in the early stages of development. Though there is not a vaccine currently approved to prevent breast cancer, research in this area furthers the knowledge base that can one day improve breast cancer care.
Talk with your health care provider about clinical trials to learn if there is one that is right for you. You can also visit breastcancertrials.org, which in collaboration with Susan G. Komen®, offers a custom matching service to help find clinical trials that fit your needs.
For questions or additional information about clinical trials, contact Komen’s Patient Care Center at 1- 877 GO KOMEN (1-877-465-6636) or email helpline@komen.org.
