A small clinical trial shows promising results for patients with triple-negative breast cancer who received an investigational vaccine designed to prevent recurrence of tumors.
Conducted at Washington University School of Medicine in St. Louis with a therapy designed by WashU Medicine researchers, the trial is the first to report results for this type of vaccine — known as a neoantigen DNA vaccine — for breast cancer patients.
The study, which found the vaccine to be well-tolerated and to stimulate the immune system, is available November 14 in the journal Genome Medicine.
The phase I clinical trial — conducted at Siteman Cancer Center, based at Barnes-Jewish Hospital and WashU Medicine — involved 18 patients diagnosed with triple-negative breast cancer that was not metastatic, meaning it had not spread to other organs. Each patient received the standard of care and three doses of a personalized vaccine tailored to home in on key mutations in their specific tumor and train immune cells to recognize and attack any cells bearing these mutations.
Following treatment, 14 of 18 patients showed immune responses to the vaccine and, after three years, 16 patients remained cancer-free. While the early-stage trial was designed to evaluate safety of the vaccine and did not include a control group to determine efficacy, the researchers analyzed historical data from patients with triple-negative breast cancer treated with the standard of care only. In that group, on average, about half of patients remained cancer-free at three years post-treatment.
For this trial, patients with triple-negative breast cancer who still had evidence of a tumor remaining after a first round of chemotherapy were eligible to participate. Such patients are at high risk of cancer recurrence even after the remaining tumor is surgically removed. After surgical removal, the research team analyzed and compared the tumor tissue with the same patient’s healthy tissue to find unique genetic mutations in the cancer cells. Such mutations in a patient’s cancer cells alter the proteins only in the tumor, making it possible to train the immune system to go after the altered proteins and leave healthy tissues alone.
Using software they designed, the researchers selected altered proteins — called neoantigens — that were made by the patients’ tumors and that were identified as most likely to trigger a strong immune response. On average, each patient’s vaccine contained 11 neoantigens (ranging from a minimum of four to a maximum of 20) specific to their tumor.
Washington University School of Medicine in St. Louis release on Newswise
