Scientists at the University of Washington Study Breast Cancer Vaccine

Early phase studies by scientists at the University of Washington found that a plasmid DNA breast cancer vaccine may produce favorable outcomes, generating anti-tumor immunity. The study, published in JAMA Oncology, analyzed the efficacy of three different doses of a plasmid-based vaccine that encodes ERBB2-specific type 1 T cells into the intracellular domain (ICD).

ERBB2-Specific type 1 T cells, previously known as HER2-specific type 1 T cells, are known to target HER2. HER2, human epithelial growth factor receptor 2, is found on the cell surface. In approximately 30% of breast cancers, HER2 is overproduced, making these cancers more aggressive and likely to recur.

This phase I clinical trial recruited 66 female patients with advanced-stage ERBB2-positive breast cancer treated between 2001 and 2010. Patients received one of the three vaccine doses: 10, 100, or 500 mcg. According to the study in JAMA Oncology, “The vaccine was administered intradermally once a month with a soluble granulocyte–macrophage colony-stimulating factor as an adjuvant for three immunizations. Toxicity evaluations occurred at set intervals and yearly. Peripheral blood mononuclear cells were collected for evaluation of immunity.”

Patients were followed for a median follow-up of 10 years; however, follow-ups ranged from 3 to 13 years. Given the data, researchers determined that the vaccine was safe for patients. The vaccine’s side effects resembled the COVID vaccine, the most common being injection site pain or redness, fever, chills, and other flu-like symptoms. In addition to being tolerable, the vaccine triggered a cytotoxic immune response as the researchers had anticipated.

“If the results of the new randomized-controlled phase II trial of the vaccine are positive, it will be a strong signal for us to rapidly move forward to a definitive phase III trial,” said Mary L. Disis, MD, a UW professor of medicine, Division of Medical Oncology, and director of the Cancer Vaccine Institute to the University of Washington News. “I have high hopes that we’re close to having a vaccine that can effectively treat patients with breast cancer.” Researchers are currently recruiting for phase II clinical trials.