01-08-2025
Is There Really About to Be a Breast Cancer Vaccine?
For decades, the idea of a vaccine that could prevent breast cancer has felt more like science fiction than science. But recently, headlines touting 'breakthroughs' and 'game-changers' have sparked a new wave of hope and some skepticism. Could we really be on the cusp of immunizing against one of the most common and deadly cancers affecting women worldwide?
Behind the buzz are early-stage clinical trials, promising preliminary results and a growing understanding of how the immune system can be trained to recognize and attack cancer cells. As researchers push forward, the science behind these potential vaccines—and what they might mean for the future of cancer prevention—is becoming increasingly compelling.
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How a Breast Cancer Vaccine Could Work and What Makes It Different
A breast cancer vaccine is a type of immunotherapy designed to prevent, treat or reduce the risk of breast cancer recurrence by training the body's immune system to recognize and attack cancer cells.
There are two main types under development.
Preventive (Prophylactic) Vaccines:These are meant to stop cancer before it starts—similar to how traditional vaccines prevent infectious diseases like measles or HPV. For breast cancer, preventive vaccines are still experimental and are generally being tested on people who are considered high risk (like those with BRCA mutations or a strong family history).
Therapeutic Vaccines:These are designed for people who already have breast cancer or have completed treatment but are at risk of recurrence. The goal is to boost the immune response against cancer-specific markers (like HER2 or mammaglobin-A), so the body can find and destroy any remaining cancer cells.
'Unlike traditional vaccines for infectious diseases (such as flu or COVID-19), which prevent infections caused by external pathogens, breast cancer vaccines target abnormal cellular changes to either prevent cancer or treat it by reducing recurrence,' Dr. Marie Ward, regional director of breast surgery at NYC Health + Hospitals's Jacobi Medical Center, tells Flow Space.
By exposing the immune system to these antigens, the vaccine helps it 'learn' what cancer cells look like, so it can mount a stronger, more targeted attack.
Where Does the Research Stand?
While no breast cancer vaccine is currently approved for widespread use, several promising vaccine candidates are in clinical trials, targeting different approaches to breast cancer, including primary prevention and recurrence prevention.
As of mid-2025, Ward says there are at least 15 breast cancer vaccine clinical trials in various stages in the U.S., some in phase II and III.
She says some notable examples include:
NeuVax (targets Her2): advanced trials
mRNA vaccines (e.g., MUC1-based) show promising early results in disease-free survival (DFS) and reduction of recurrence
Alpha-lactalbumin vaccines for triple-negative breast cancer
One of the most closely watched efforts is being led by the Cleveland Clinic, which launched its phase I trial of a preventive breast cancer vaccine in 2021.
'This vaccine targets α-lactalbumin—a protein normally produced only during lactation but abnormally expressed in many triple-negative breast cancers—a particularly aggressive and hard-to-treat subtype,' Dr. Brooke Davis, breast medical oncologist at Oncology Specialists of Charlotte in North Carolina, tells Flow Space.
The trial is testing the vaccine in women who are currently cancer-free but considered high-risk due to genetic mutations (like BRCA1/2) or family history. The current focus is on evaluating safety, immune response and tolerability. If early results are promising, the study will expand to larger groups and later-phase trials to assess long-term protection
Meanwhile, therapeutic vaccines are also advancing.
These vaccines don't aim to prevent the disease from occurring, but rather to help the immune system better identify and destroy cancer cells, especially those that may linger after treatment and cause recurrence. For instance, researchers are developing HER2-targeted vaccines, which are designed to activate immune cells against breast cancers that overexpress the HER2 protein.
'These are currently being studied in combination with other treatments, such as checkpoint inhibitors, in hopes of amplifying their effectiveness,' adds Davis.
Additionally, mRNA vaccine technology is being adapted for breast cancer applications.
Companies like BioNTech and Moderna, which were instrumental in developing COVID-19 vaccines, are now exploring whether personalized mRNA vaccines can teach the immune system to target tumor-specific neoantigens—essentially custom-building a vaccine unique to each patient's cancer.
Early results across multiple trials have shown that these vaccines are capable of producing measurable immune responses and appear to be safe, with relatively mild side effects.
However, most studies are still in phase I or phase II, meaning it's too soon to know whether they will lead to significant reductions in cancer risk or recurrence. That said, both interest and investment in this space are growing rapidly. The National Cancer Institute and the Department of Defense are funding numerous breast cancer vaccine studies, reflecting growing institutional confidence in the field.
Epidemiologist Dr. Scarlett Lin Gomez, co-leader of the Cancer Control Program at University of Central South Florida who specializes in studying breast cancer rates among Asian-American women is currently conducting the CRANE study. Its goal is to understand the risk factors underlying the high and increasing rates of breast cancer in Asian American females.
'But in a more general sense, raising awareness among the medical community about the severity of breast cancer and its rising cases within minority groups only sheds light on how much a vaccine would be a game changer,' she notes.
However, researchers caution that a universal breast cancer vaccine—one that could be given to the general population, much like the HPV vaccine—is likely still many years away, if it proves possible at all.
'The ideal future model combines both: a standard vaccine base with individualized components tailored to a patient's unique tumor biology,' explains Ward.
What's Next?
Every breast cancer vaccine trial underway today is doing more than just testing a single intervention; it's helping to define the future of cancer prevention and treatment. While we're still years away from routine, widespread vaccination against breast cancer, researchers are gathering critical insights that are shaping the next generation of cancer vaccines.
Ward says one of the major milestones the field is working toward is the successful demonstration of reduced recurrence or prevention rates in large, randomized phase III trials, which could lead to regulatory approval, particularly for high-risk populations.
But reaching that point, she emphasizes, requires a more sophisticated approach than a vaccine alone. 'One of our key learnings is that vaccines are far more effective when combined with other forms of immunotherapy, such as checkpoint inhibitors,' Ward explains. 'Cancer is expert at evading immune recognition. You need to unmask it—and that often takes multiple tools working in tandem.'
Another essential insight has come from understanding which antigens best trigger a protective immune response. 'We're learning to distinguish between shared antigens, which are common across many tumors, and personalized neoantigens, which are unique to each patient's cancer,' says Ward. 'Both have potential, but personalizing the immune response could offer stronger, longer-lasting protection.'
Technological innovation is playing a major role in shaping these next-generation vaccines, as well, adds Davis. She says that with mRNA platforms and machine learning, scientists are able to design and adapt vaccines more rapidly than ever before, and these tools allow us to evolve the vaccine alongside the tumor, which is critical because cancer isn't static, it changes.
At the same time, researchers are gaining a better understanding of why some vaccines underperform.
One of the most promising avenues for current vaccines is minimal residual disease settings—after the primary tumor has been removed or treated, but before the cancer has a chance to come back. In these scenarios, the tumor burden is low, and the immune system has a better shot at clearing out any remaining cells.
Ultimately, experts agree that breast cancer vaccines will more than likely be part of a larger therapeutic strategy rather than a standalone solution.
'We're likely to see vaccines used alongside existing therapies—chemotherapy, targeted drugs and immunotherapy—for a synergistic benefit,' Ward says. 'It's about boosting the immune system in a smarter, more targeted way. But the lessons we're learning now are invaluable. They're helping us build smarter, safer and more effective vaccines and bringing us closer to a future where cancer prevention is proactive, not reactive.'
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