Scientists testing a malaria vaccine in pregnant women made a surprising discovery that shows promise for treating cancer.
When the team created the protein the malaria parasite uses to adhere to the placenta and added a toxin, they discovered that the protein is identical to a carbohydrate found in cancer cells.
This combination of malaria protein and toxin seeks out the cancer cells, is absorbed, the toxin released inside, and then the cancer cells die. This process has been witnessed in cell cultures and in mice with cancer. Ali Salanti from the immunology and microbiology department at the University of Copenhagen, says:
“For decades, scientists have been searching for similarities between the growth of a placenta and a tumor. The placenta is an organ, which within a few months grows from only few cells into an organ weighing approx. two 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.”
After making the discovery, Salanti contacted cancer researcher Mads Daugaard from the University of British Columbia. In collaboration, the two groups have generated results, which they hope will provide the basis for a drug against cancer.
“We examined the carbohydrate’s function. In the placenta, it helps ensure fast growth. 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,” Salanti explains.
3 Types of Human Tumors
The scientists have tested thousands of samples from brain tumors to leukemias and results show that the malaria protein attacks more than 90 percent of all types of tumors.
The drug has been tested on mice that were implanted with three types of human tumors. With non-Hodgkin’s lymphoma, the treated mice’s tumors were about a quarter the size of the tumors in the control group.
With prostate cancer, the tumors disappeared in two of the six treated mice a month after receiving the first dose. With metastatic bone cancer, five out of six of the treated mice were alive after almost eight weeks, compared to none of the mice in a control group.
“It appears that the malaria protein attaches itself to the tumor without any significant attachment to other tissue. 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,”
says PhD student Thomas Mandel Clausen, who has been part of the research project for the last two years.
Unsafe for Pregnant Women
It would appear that the only snag is the fact that the treatment would not be available for pregnant women.
“Expressed in popular terms, the toxin will believe that the placenta is a tumor and kill it, in exactly the same way it will believe that a tumor is a placenta,” explains Salanti.
The University of Copenhagen has created the biotech company, VAR2pharmaceuticals, to oversee clinical development. The goal will be to conduct tests on humans.
“The earliest possible test scenario is in four years time. The biggest questions are whether it’ll work in the human body, and if the human body can tolerate the doses needed without developing side effects. But 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,” Salanti says.
Salanti, Ali et al.
Targeting Human Cancer by a Glycosaminoglycan Binding Malaria Protein
Cancer Cell , Volume 28 , Issue 4 , 500 – 514
Top Illustration: Chris Martino/Flickr