A vaccine for breast cancer has passed initial clinical trials
Preliminary results of a study suggest that the breast cancer DNA vaccine is “very safe” in generating a solid anti-tumor immune response. Phase 2 clinical trial to test its efficacy gets underway.
New hope for the fight against breast cancer. An experimental vaccine has just passed the first phase 1 trial in humans with flying colors, proving to be “very safe” in generating a solid anti-tumor immune response. Telling the tale is a new study published in Jama Oncology by researchers at the University of Washington School of Medicine. They suggest that the experimental vaccine can treat different types of breast cancer. Their results may pave the way for a more significant phase 2 clinical trial to test its efficacy.
A phase 1 study, remember, is defined as a trial designed to evaluate a drug’s safety. In this case, researchers analyzed whether the experimental vaccine could target a protein called human epidermal growth factor receptor 2, Her2, and generate an immune response to this protein. Although Her2 is found on the surface of many cells, in as many as 30 percent of breast cancers, it is overproduced by up to 100 times the average amount. Hence, the name “Her2-positive” tumors tend to be more aggressive and more likely to recur.
The overproduction of Her2, however, also triggers an immune reaction that can be beneficial: patients who develop a type of immune response called cytotoxic immunity are less likely to recur after treatment and have more prolonged survival. To stimulate this immune response, researchers designed a DNA vaccine that contains instructions for a part of Her2 known to elicit more robust cytotoxic immune responses. Unlike protein vaccines, which precisely contain part or all of the protein you want the immune system to target, DNA vaccines contain DNA instructions for the target protein. Once injected, the cells absorb the DNA, which begins to produce the protein encoded in the instructions and then present it to the immune system to generate a cytotoxic immune response thus.
Sixty-six women who had metastatic breast cancer had completed a course of standard therapy and achieved complete remission participated in the study. Once divided into three groups, all patients received three injections: the first group was given a low dose of the vaccine, the second an intermediate dose, and the third a high dose. The participants were then monitored with an average follow-up of nearly ten years to observe that the vaccine did not trigger an autoimmune response against other healthy tissues. “The results showed that the vaccine was very safe,” the authors comment. “The most common side effects we saw in about half of the patients were similar to those seen with Covid vaccines: redness and swelling at the injection site and perhaps some fever, chills and flu-like symptoms.”
The vaccine also generated the desired cytotoxic immune response without triggering severe side effects (with a more robust response in patients who received the medium dose). Although the study was not designed to analyze the vaccine’s efficacy, the researchers noted that the results are promising, especially considering that only about 50 percent of advanced Her2 breast cancer patients survive for more than five years. “We have now been following these women for ten years, and 80 percent of them are still alive,” the researchers concluded.