A phase I clinical trial at Washington University School of Medicine in St. Louis indicates that a personalized vaccine shows promise in preventing the recurrence of triple-negative breast cancer, an aggressive form of the disease. The neoantigen DNA vaccine, designed by WashU Medicine researchers, is tailored to target key mutations in each patient's specific tumor, training immune cells to recognize and attack any cells bearing these mutations.
Trial Details and Findings
The study, published in Genome Medicine, involved 18 patients with non-metastatic triple-negative breast cancer. Each patient received the standard of care and three doses of the personalized vaccine. The trial's primary goal was to evaluate the vaccine's safety and its ability to stimulate the immune system.
Following treatment, 14 of the 18 patients demonstrated immune responses to the vaccine. After three years, 16 patients remained cancer-free. While the trial lacked a control group, researchers compared the outcomes to historical data of triple-negative breast cancer patients treated with standard of care alone, where approximately half remained cancer-free at three years post-treatment.
"These results were better than we expected," said William E. Gillanders, MD, the Mary Culver Distinguished Professor of Surgery at WashU Medicine. "We are encouraged by what we’re seeing with these patients so far."
Addressing an Unmet Need in Triple-Negative Breast Cancer
Triple-negative breast cancer lacks targeted therapies and is typically treated with surgery, chemotherapy, and radiation therapy. It is more prevalent among African American patients. In this trial, one-third of the participants were African American.
Patients eligible for the trial had residual tumor evidence after initial chemotherapy, placing them at high risk of recurrence even after surgical removal of the remaining tumor. The research team analyzed tumor tissue and compared it with healthy tissue to identify unique genetic mutations in the cancer cells. These mutations, or neoantigens, are specific to the tumor, allowing the immune system to target altered proteins while sparing healthy tissues.
Personalized Vaccine Design
Using custom-designed software, researchers selected neoantigens made by the patients’ tumors that were most likely to trigger a strong immune response. Each patient’s vaccine contained an average of 11 neoantigens, ranging from 4 to 20, specific to their tumor.
Obi Griffith, PhD, and Malachi Griffith, PhD, computational biologists at WashU Medicine, led the software development. Their goal is to make these computational resources widely accessible to cancer researchers and clinicians globally. The software tools rank potential neoantigens based on their potential to stimulate the immune system to attack cancer cells.
Future Directions
Several studies of cancer vaccines are ongoing at Siteman Cancer Center. These personalized vaccines are being investigated in combination with immunotherapies, such as checkpoint inhibitors, to boost T cell action.
"We are excited about the promise of these neoantigen vaccines," Gillanders said. "We are hopeful that we will be able to bring more and more of this type of vaccine technology to our patients and help improve treatment outcomes in patients with aggressive cancers."
