Long-Term Breast Cancer Survivors: Vaccine Boosts Immune Response & Shows Promise in Trials
More than two decades after an experimental vaccine was tested on a small group of women with advanced breast cancer, all participants remain alive. Researchers state that this extended survival is unusual for individuals with metastatic breast cancer, prompting renewed scientific investigation into the case.
Uncovering the Key to Long-Term Survival
Researchers at Duke Health revisited the immune systems of the women involved in the clinical trial, which was led by Herbert Kim Lyerly, M.D., George Barth Geller Distinguished Professor of Immunology at Duke University School of Medicine. They were surprised to find that the women continued to possess robust immune cells capable of recognizing their cancer, even years after the initial treatment.
The Role of CD27
These immune cells all shared a specific marker called CD27. This marker is crucial for the immune system’s ability to remember previous threats and mount a response when they reappear. The findings, published in Science Immunology, suggest that CD27 could be a key to developing more effective cancer vaccines.
Boosting the Immune Response in Lab Tests
To further investigate, the research team conducted experiments on mice. They combined a vaccine targeting HER2 – a protein found on some cells, including breast cancer cells – with an antibody designed to activate CD27. The results were significant: nearly 40% of mice receiving the combined treatment experienced complete tumor disappearance, compared to only 6% of mice treated with the vaccine alone.
Analysis revealed that the CD27 antibody enhanced the activity of CD4+ T cells, a type of immune cell.
A New Look at “Helper” Cells
According to Zachary Hartman, Ph.D., senior author of the study and associate professor in the Departments of Surgery, Integrative Immunology and Pathology at Duke University School of Medicine, CD4+ T cells, often referred to as “helper” cells, are often overlooked in cancer research. Most research focuses on CD8+ “killer” T cells, which directly attack tumors. This study indicates that helper cells may be equally important, driving long-lasting immune memory and supporting other immune cells.
Adding another antibody to further support CD8+ T cells increased tumor rejection rates in mice to almost 90%.
What This Means for Future Treatments
The research team also found that the CD27 antibody needed to be administered only once, alongside the vaccine, to achieve lasting effects. This simplicity could facilitate its integration with existing cancer treatments, such as immune checkpoint inhibitors and antibody-drug conjugates.
Hartman believes these findings could unlock the full potential of cancer vaccines. “We’ve known for a long time that vaccines can work against cancer, but they haven’t lived up to the hype,” he said. “This could be a missing piece of the puzzle.”
The study received funding from the National Institutes of Health (117 R01CA238217-01A1/02S1) and the Department of Defense (W81XWH-20-1-034618 and W81XWH-21-2-0031).
Frequently Asked Questions
What marker was found on the immune cells of the women in the trial?
The immune cells shared a specific marker known as CD27.
What percentage of mice saw their tumors disappear completely with the combined vaccine and antibody treatment?
Nearly 40% of mice that received the combined treatment saw their tumors disappear completely.
What type of immune cell was found to be enhanced by the CD27 antibody?
The CD27 antibody greatly enhanced the activity of CD4+ T cells.
As research continues, could this discovery lead to new and more effective cancer vaccine strategies for a wider range of cancers?