A vaccine against the most aggressive and deadly form of breast cancer is one step closer to reality.

The Cleveland Clinic announced Tuesday it's launching a first-of-its kind human trial testing a shot designed to prevent triple-negative breast cancer, which currently doesn't respond to hormone or targeted drug therapies and can only be prevented with mastectomy.

Until now, developments in triple-negative breast cancer vaccines have been limited to lab work and animal research. The human trial can begin now that the US Food and Drug Administration approved an investigational new drug application for the shot.

While the trial will only include early-stage triple-negative breast cancer survivors who are at high risk for recurrence, the researchers hope to next take the vaccine to healthy people at high risk for the disease, like those with BRCA1 gene mutations.

"Long term, we are hoping that this can be a true preventive vaccine that would be administered to healthy women to prevent them from developing triple-negative breast cancer, the form of breast cancer for which we have the least effective treatments," Dr. G. Thomas Budd, of Cleveland Clinic's Taussig Cancer Institute and principal investigator of the study, said in a press release.

Participants will receive three shots

Triple-negative breast cancer accounts for about 12 percent to 15 percent of all breast cancers and kills nearly a quarter of patients within five years of diagnosis. It's more common among African-American women and those with BRCA1 mutations.

The presence of a certain protein, α-lactalbumin, usually accompanies the disease, even though it's only supposed to appear when a person is lactating.

The vaccine, then, will target that protein, prompting the immune system to stave off emerging breast tumors that express it. The shot will also include a drug that alerts the immune system to a-lactabalbumin so that it can halt emerging tumor growth.

The trial will include 18 to 24 patients who are tumor-free after being treated for early-stage triple-negative breast cancer within the past three years. They'll receive three shots, each two weeks apart. Researchers will start with low doses in just a few patients and monitor them closely before upping the dose and including more participants.

"Once we've figured out how much of the vaccine we can give, we'll look at its effects on the immune system," Budd told the Cleveland Clinic. "That will help us know whether the vaccine is doing what we want it to do, and then we'll expand each dose level."

The study is estimated to be completed in September 2022. It's funded by the US Department of Defense.

"This vaccine strategy has the potential to be applied to other tumor types," added Tuohy.

"Our translational research program focuses on developing vaccines that prevent diseases we confront with age, like breast, ovarian and endometrial cancers. If successful, these vaccines have the potential to transform the way we control adult-onset cancers and enhance life expectancy in a manner similar to the impact that the childhood vaccination program has had."

This article was originally published by Business Insider.

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