For Chase Johnson, an unexpected change in her dog’s behavior became a life-altering warning. At 31, Johnson noticed her usually calm pet growing anxious and unusually protective, refusing to leave her side. One day, the dog persistently nudged his nose against her chest. Curious and concerned, Johnson checked herself and felt a hard lump in her breast.
“I wasn’t someone who was good at doing self-exams, I don’t think I would have found it otherwise,” said Johnson, now 36, who lives in Cary, North Carolina. She had no family history of breast cancer and no reason to suspect she was at risk.
In February 2021, Johnson received a diagnosis that would upend her life: triple-negative breast cancer, an aggressive subtype known for its rapid growth and limited treatment options. What followed was months of intensive therapy—and eventually, participation in a pioneering clinical trial that researchers hope could redefine how the disease is treated and even prevented.
Why Triple-Negative Breast Cancer Is So Difficult to Treat
Breast cancer treatment is often guided by the presence of specific biological markers on tumor cells. Many breast cancers rely on estrogen or progesterone to grow, or produce excessive amounts of a protein called HER2. Therapies that target these markers have transformed outcomes for millions of patients.
Triple-negative breast cancer, however, lacks all three. Without these targets, doctors are left with fewer tools, and patients typically undergo a combination of chemotherapy, surgery, and radiation. The disease is also more likely to spread and return than other breast cancer types.
Johnson endured four months of intravenous chemotherapy before undergoing surgery to remove her tumor and affected lymph nodes. She then completed an additional six months of oral chemotherapy along with 24 rounds of radiation. While her treatment was ultimately successful, remission did not bring peace of mind.
Living With the Risk of Recurrence
For patients with triple-negative breast cancer, the threat of recurrence looms large. About 40% experience a return of the disease within five years of treatment. When it does come back, it often spreads to critical organs, including the brain, lungs, liver, and lymph nodes.
After completing standard treatment, Johnson began searching for ways to reduce her risk. In December 2022, she enrolled in a Phase 1 clinical trial at the Cleveland Clinic testing an experimental vaccine designed to prevent triple-negative breast cancer from returning—and possibly stop it from developing in high-risk individuals altogether.
“I am literally doing anything possible to make sure this doesn’t come back,” Johnson said. “For triple negative, the resources are so limited; if the traditional treatment methods don’t work, you’re just kind of out of luck.”
A Vaccine That Trains the Immune System
The vaccine targets a protein called α-lactalbumin, which appears in roughly 70% of triple-negative breast cancers. Under normal conditions, the protein is produced only during breastfeeding. In cancer cells, however, it becomes a potential red flag for the immune system.
Researchers aim to teach the body to recognize α-lactalbumin as dangerous. The vaccine stimulates the production of T-cells that can seek out and destroy cells carrying the protein before tumors can grow or return.
If successful, the approach could shift the focus from treating cancer after it appears to stopping it before it takes hold.
Encouraging Early Trial Results
Initial findings from the Phase 1 trial were presented at the San Antonio Breast Cancer Symposium in Texas. The study included 35 women and focused on safety and immune response rather than long-term outcomes.
Participants were grouped into three categories: women who had completed treatment and were cancer-free but at high risk of recurrence; women who still had residual tumor cells after treatment; and women who had not been diagnosed with cancer but carried genetic risk factors such as BRCA mutations.
Researchers found that 74% of participants developed an immune response to the vaccine. What that response ultimately means for preventing cancer remains unknown.
“Whether this immune response will translate into reducing the risk of recurrence or preventing breast cancer, we don’t know that yet,” said Dr. G. Thomas Budd, the trial’s lead investigator and a medical oncologist at Cleveland Clinic’s Cancer Institute.
Safety Considerations and Next Steps
The vaccine was generally well tolerated. Most side effects were mild and limited to redness or swelling at the injection site. No serious adverse events were reported.
One concern is the possibility of triggering an autoimmune reaction, particularly in women who may breastfeed in the future, since α-lactalbumin is naturally produced during lactation. For that reason, Budd does not recommend the trial for women planning to breastfeed.
Despite the uncertainties, researchers view the results as a promising first step. A Phase 2 trial, expected to begin late next year, will be the first to evaluate whether the vaccine can actually reduce recurrence rates.
