Early Trial Shows Preventive Breast Cancer Vaccine Is Safe and Triggers Strong Immune Response
Researchers at the Cleveland Clinic have shared encouraging early results from a Phase I clinical trial testing a vaccine designed to prevent triple-negative breast cancer (TNBC), one of the most aggressive and difficult-to-treat forms of breast cancer. The findings were presented at the San Antonio Breast Cancer Symposium, a major international meeting focused on advances in breast cancer research, and they mark an important milestone in the long-term effort to develop cancer-preventive vaccines.
The Phase I study focused primarily on safety and immune response, not on whether the vaccine definitively prevents cancer. Even so, the results suggest that the approach is scientifically sound and worth pursuing further. According to the research team, the investigational vaccine was safe, well tolerated, and capable of stimulating the immune system in a large proportion of participants.
What the Phase I Trial Found
The trial showed that 74% of participants developed a measurable immune response after receiving the vaccine. This is a key outcome in an early-stage study, as it demonstrates that the immune system recognizes and reacts to the vaccineโs target. Importantly, the study also established the maximum tolerated dose, a crucial step before moving on to larger trials.
In terms of safety, side effects were generally mild. The most commonly reported reactions were localized skin inflammation at the injection site, such as redness or swelling. No serious safety concerns were identified, reinforcing the conclusion that the vaccine can be administered safely at the tested doses.
The study was led by researchers from Cleveland Clinicโs Cancer Institute, with Dr. G. Thomas Budd serving as the principal investigator. The team emphasized that while Phase I trials are not designed to prove effectiveness, the combination of safety and immune activation makes the results particularly promising.
Understanding the Clinical Trial Design
The Phase I trial, officially registered as NCT04674306, began in 2021 and was conducted at Cleveland Clinicโs Main Campus in collaboration with Anixa Biosciences, Inc. A total of 35 participants were enrolled across three distinct cohorts, each chosen to address different high-risk scenarios related to triple-negative breast cancer.
- Phase Ia included 26 patients who had previously been treated for early-stage TNBC. These individuals were cancer-free at enrollment but remained at high risk of recurrence, having completed treatment within the previous three years.
- Phase Ib enrolled four cancer-free individuals with genetic mutations linked to elevated breast cancer risk, such as BRCA1 mutations. These participants had elected to undergo preventive mastectomy, making them an important group for studying cancer prevention strategies.
- Phase Ic involved five early-stage TNBC patients who had received pre-operative chemoimmunotherapy, surgery, and treatment with pembrolizumab, an immune checkpoint inhibitor. These patients still had residual cancer in breast tissue, placing them at increased risk for recurrence.
By including these diverse cohorts, researchers were able to observe how different high-risk populations responded to the vaccine, adding depth to the safety and immune-response data.
Why Triple-Negative Breast Cancer Needs New Solutions
Triple-negative breast cancer accounts for only 10โ15% of all breast cancer cases, but it is responsible for a disproportionately high number of breast cancer-related deaths. Unlike other breast cancer subtypes, TNBC lacks estrogen receptors, progesterone receptors, and HER2 expression. This means it does not respond to hormonal therapies or many targeted treatments, leaving chemotherapy and immunotherapy as the primary options.
TNBC is also twice as common in Black women and makes up 70โ80% of breast tumors in patients with BRCA1 gene mutations. These factors highlight the urgent need for better preventive and therapeutic strategies, particularly for populations at higher risk.
How the Vaccine Works
The investigational vaccine is based on decades of research led by the late Vincent Tuohy, Ph.D., who held the Mort and Iris November Distinguished Chair in Innovative Breast Cancer Research at Cleveland Clinic. His work laid the foundation for this approach to cancer prevention.
The vaccine targets a specific protein called ฮฑ-lactalbumin. This protein is normally produced during lactation but is absent in healthy breast tissue after lactation ends. Crucially, ฮฑ-lactalbumin is present in most triple-negative breast cancers, making it an attractive and selective target.
The idea behind the vaccine is straightforward but powerful: by training the immune system to recognize ฮฑ-lactalbumin, the body may be able to attack cancer cells early, potentially stopping tumors from forming or recurring. Preclinical studies in animal models showed that activating immunity against this protein was safe and effective in preventing breast tumors, providing the rationale for human trials.
What Comes Next: Phase II and Beyond
With Phase I complete, the next step is a Phase II clinical trial, which will focus on efficacy rather than just safety. Anixa Biosciences has announced plans to launch this next phase late next year, with an expected duration of two to three years.
Phase II will aim to answer the most important question: can this vaccine actually reduce the risk of developing triple-negative breast cancer or prevent recurrence in high-risk individuals? Larger participant numbers and longer follow-up periods will be essential to determine real-world clinical benefit.
Commercialization and Broader Impact
Anixa Biosciences is the exclusive worldwide licensee of the breast cancer vaccine technology developed at Cleveland Clinic. Under the licensing agreement, Cleveland Clinic is entitled to royalties and other commercialization revenues if the vaccine ultimately reaches the market.
Beyond TNBC, researchers see broader implications for this work. The success of a preventive cancer vaccine could open the door to similar immunization strategies for other cancers, particularly those with well-defined tumor-specific antigens.
Why This Research Matters
Cancer vaccines have long been a goal in oncology, but progress has been slow due to the complexity of the immune system and cancer biology. This study stands out because it focuses on prevention, not just treatment, and targets a protein that is largely absent from normal adult tissue.
While it is still early, the results suggest that immunization against cancer-associated proteins may one day become part of standard preventive care for high-risk individuals. For patients facing the challenges of triple-negative breast cancer, that possibility represents a meaningful step forward.
Research paper reference:
https://www.nature.com/articles/nm.XXXX (Nature Medicine โ original preclinical and foundational research on ฮฑ-lactalbumin breast cancer vaccination)
