Researchers seeking a vaccine to protect pregnant women against malaria have stumbled across what they believe to be a potential cancer treatment. In cell cultures and mice with multiple forms of the disease, malaria proteins armed with a toxin sought out and absorbed cancer cells, released the toxin and then destroyed the cells, according to a news release.

Malaria researchers at the University of Copenhagen and cancer scientists at the University of British Columbia, who published their findings Monday in the journal Cancer Cell, said they plan to test their results in humans within four years.

“For decades, scientists have been searching for similarities between the growth of a placenta and a tumor,” Ali Salanti, a professor in the department of immunology and microbiology at the University of Copenhagen, said in the release. “The placenta is an organ, which within a few months grows from only few cells into an organ weighing [approximately] 2 pounds, and it provides the embryo with oxygen and nourishment in a relatively foreign environment. In a manner of speaking, tumors do much the same— they grow aggressively in a relatively foreign environment.”

Salanti’s research— conducted with Mads Daugaard, head of the Laboratory of Molecular Pathology at the Vancouver Prostate Center at the University of British Columbia— suggests that the carbohydrate the malaria parasite attaches itself to in the placenta in pregnant women is identical to a carbohydrate found in cancer cells.

“We examined the carbohydrate’s function. In the placenta, it helps ensure fast growth,” Salanti said in the release. “Our experiments showed that it was the same in cancer tumors. We combined the malaria parasite with cancer cells, and the parasite reacted to the cancer cells as if they were a placenta and attached itself.”

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To test the power of the toxin with the malaria parasite against cancer, researchers analyzed thousands of samples— including brain tumors and leukemias— and observed that the combination could target more than 90 percent of all types of tumors.

They also evaluated the drug in mice that were implanted with three types of human tumors: non-Hodgkin’s lymphoma, prostate cancer and metastatic bone cancer. The treated mice with non-Hodgkin’s lymphoma saw their tumors reduced to about one-fourth the size of the tumors in the control group. In the treated mice with prostate cancer, tumors in two of the six rodents disappeared. And five out of the six treated mice that had metastatic bone cancer stayed alive, compared to none of the mice in the control group.

“It appears that the malaria protein attaches itself to the tumor without any significant attachment to other tissue,” Thomas Mandel Clausen, a Ph.D. student at the University of Copenhagen, who has been part of the research for the past two years, said in the release. “And the mice that were given doses of protein and toxin showed far higher survival rates than the untreated mice. We have seen that three doses can arrest growth in a tumor and even make it shrink.”

Salanti said in the researchers’ forthcoming test in humans, they will analyze drug function and dosing as well as any potential side effects.

“We’re optimistic because the protein appears to only attach itself to a carbohydrate that is only found in the placenta and in cancer tumors in humans,” he said in the release.