It all began with a protein that shouldn’t be there.

In healthy women, α-lactalbumin is a protein produced during lactation, a vital ingredient in the making of milk. But decades ago, scientists noticed something strange: this milk-making protein kept appearing in tumors. Not just any breast cancer, but the most aggressive kind — triple-negative breast cancer, a form that evades hormone treatments and spreads quickly.

Now, a new vaccine designed to train the body’s immune system to attack this rogue protein is showing promise in early trials. And if it works, researchers say it could help do for breast cancer what other vaccines have done for diseases like polio and hepatitis B — prevent it altogether.

“If this works and is able to prevent cancer, then we can perhaps eliminate breast cancer as a disease,” Dr. Amit Kumar, CEO of Anixa Biosciences told The New York Post.

A Clever Target

The vaccine, developed by Anixa Biosciences in collaboration with the Cleveland Clinic, is based on a simple but elegant idea: teach the immune system to spot and destroy cancer cells before they become dangerous.

To do that, scientists focused on α-lactalbumin. This protein is not normally present in the body unless a woman is breastfeeding. But in up to 70% of triple-negative breast cancer cases, tumors begin producing it. That makes the protein an ideal “retired” target — the immune system can strike it without harming healthy tissue.

Dr. Kumar described the approach in an interview with Vogue:

“The vaccine is designed to mobilize the patient’s immune system to find, recognize, and destroy breast cancer cells for primary prevention.”

In a small phase 1 trial involving 35 women — many with either early-stage TNBC or a genetic risk for breast cancer — over 75% developed a strong immune response. Blood tests revealed antibodies and white blood cells primed to recognize α-lactalbumin.

“The study thus far showed that the vaccine is overall well tolerated and resulted in an immune response in most patients,” said Dr. Rima Patel, an oncologist at Mount Sinai.

Side effects were mild. Most reported only minor irritation at the injection site.

A Vaccine Unlike Others

Cancer vaccines are not like the ones we take to ward off infections. The immune system is generally trained to ignore the body’s own cells — and cancers, which originate from those cells, often slip under the radar. That’s why most past attempts at cancer vaccines have failed: they either didn’t generate a strong enough response, or they accidentally triggered the immune system to attack healthy tissue.

This vaccine sidesteps that by focusing on the protein that shouldn’t be there unless a woman is lactating. In other words, for women not planning to have more children, α-lactalbumin becomes a safe bullseye.

That idea, Dr. Kumar said, actually dates back about 20 years. It was first proposed by a Cleveland Clinic researcher who imagined targeting the protein in healthy women long before any tumor formed. That vision is now beginning to materialize.

The vaccine is administered in three doses spaced two weeks apart. So far, animal studies have shown that it prevents tumor formation in mice. Human trials will take more time, but researchers are cautiously optimistic.

Phase 2 trials, planned for next year, will include more participants and expand to other types of breast cancer beyond TNBC.

“We are extremely excited,” Dr. Kumar said. “If the data continues to be good, this vaccine would be game-changing.”

What Comes Next?

Despite the positive results, there are still hurdles.

Cancer prevention vaccines face a steep climb through clinical testing, especially when applied to healthy individuals. Larger trials will need to prove that the immune response not only appears but translates into real protection.

There are also logistical challenges. The current trial was funded by the U.S. Department of Defense, but future phases may depend on securing additional funding, a task that could be complicated by shifting federal budgets.

Yet the potential reward is hard to overstate. Triple-negative breast cancer affects around 14 out of every 100,000 women in the U.S. and carries a lower five-year survival rate than other types. It is difficult to treat and prone to returning even after successful therapies.

That’s what makes this vaccine so unique. It isn’t just a new form of treatment. It could be a first line of defense, offering high-risk individuals a shield before cancer takes root.

As Dr. Patel put it:

“This vaccine represents an exciting advancement and is unique in its aim to prevent TNBC, which can be more difficult to treat due to a lack of targeted treatments.”

For now, the vaccine remains in the early stages of development. But if further trials confirm its promise, it could mark the beginning of a new chapter in medicine, one where the immune system is taught to catch cancer before it begins.

And where a protein once meant for nourishing newborns may become the key to stopping breast cancer in its tracks.