Researchers stumbled upon a new tool to fight cancer in a rather unexpected place; while searching for a vaccine against malaria in pregnant women, a team of Danish scientists found that, simply put, armed malaria proteins are remarkably good at killing cancer cells. They hope to have a working prototype ready for human trials within four years' time. Their discovery has been published in the scientific journal Cancer Cell.
Professor and malaria expert Ali Salanti from the Faculty of Medical Health and Sciences, working in collaboration with cancer researcher Mads Daugaard from the University of British Columbia in Canada, revealed that the specific carbohydrate that malaria parasites attach themselves to in the human placenta is identical to a carbohydrate found in all cancer cells.
Ali Salanti's team is currently testing a vaccine against malaria on humans, and their work developing the drug led to the discovery of the carbohydrate. Salanti contacted his former fellow student and now cancer researcher, Mads Daugaard, who is head of the Laboratory of Molecular Pathology at the Vancouver Prostate Center at UBC in Canada. Seeing the potential of this finding, they went to work -- in essence, the carb gave them the perfect Trojan Horse to use against the malign cells, without the risk that normal cells would be attacked.
“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,” says Ali Salanti from the Department of Immunology and Microbiology at the University of Copenhagen..
So they set to work on weaponizing their Horse. They isolated the protein that malaria relies on to adhere to the placenta and added a toxin to it. The theory held strong up till now, but the team needed to be sure that the system worked as intended, and tested it on cell cultures and in mice with cancer. Once inside the organism or culture, the protein-toxin combination seeks out cancer cells and binds to them, only then releasing the toxin. The cancer cell dies, and regular, hard working tax paying cells aren't affected, win win!
“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,” Ali Salanti adds.
Kills cancer cells
Working together, the two universities have tested thousands of samples, ranging from brain tumors to leukemias, and the results are encouraging -- the weaponized malaria protein can attack more than 90% of all types of tumors. Another series of tests were carried out on mice implanted with three types of human tumors: one group with non-Hodgkin’s lymphoma, where the treated mice’s tumours were about a quarter the size of the tumours in the control group. For prostate cancer, the tumours 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.
“We have separated the malaria protein, which attaches itself to the carbohydrate and then added a toxin. By conducting tests on mice, we have been able to show that the combination of protein and toxin kill the cancer cells,” Mads Daugaard explains.
“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,” PhD student Thomas Mandel Clausen elaborates. He has been part of the research project for the last two years.
The only downside to this drug is that it can't be prescribed to pregnant women, for obvious reasons:
“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,” Ali Salanti states.
In collaboration with the scientists behind the discovery, the University of Copenhagen has created the biotech company, VAR2pharmaceuticals, which will drive the clinical development forward. The research teams working with Ali Salanti and Mads Daugaard are now working towards being able 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,” Ali Salanti concludes.