An experimental personalized vaccine is showing promising results in the treatment of triple-negative breast cancer, an aggressive form of the disease that lacks targeted therapies. The early clinical trial, the results of which were published in Genome Medicine, indicates the vaccine is safe and effective, teaching the immune system to eradicate remaining cancer cells.
The study involved 18 patients with triple-negative breast cancer who had already undergone chemotherapy and surgery. Researchers analyzed the patients' tumor tissues to identify unique genetic mutations and then created a personalized vaccine for each patient based on these mutations. Each patient received three doses of the vaccine.
"These results were better than we expected," said Dr. William Gillanders, professor of surgery at Washington University School of Medicine in St. Louis and senior researcher on the study. The data showed that 16 out of 18 patients remained cancer-free three years after receiving the vaccine. This compares favorably to historical data showing that only about half of patients who undergo surgery alone remain cancer-free after three years.
Triple-negative breast cancer accounts for 10% to 15% of all breast cancer cases in the United States, according to the National Breast Cancer Foundation. This subtype of breast cancer is characterized by the absence of estrogen receptors, progesterone receptors, and HER2 protein, making it unresponsive to hormone therapy and HER2-targeted drugs. Current treatment options are limited to surgery, chemotherapy, and radiation therapy.
The vaccine works by stimulating the patient's immune system to recognize and attack cancer cells bearing the identified mutations. Results from the trial showed that 14 out of the 18 patients developed an immune response to the vaccine.
"We are excited about the promise of these neo-antigen vaccines," Gillanders stated. "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."
Ongoing Research
While the initial results are encouraging, the researchers emphasize the need for larger clinical trials to confirm the vaccine's effectiveness. "We acknowledge the limitations of this type of analysis, but we are continuing to pursue this vaccine strategy and have ongoing randomized controlled trials that do make a direct comparison between the standard of care plus a vaccine, versus standard of care alone," Gillanders explained. "We are encouraged by what we’re seeing with these patients so far."
