In a Toronto laboratory, an experiment on mice is seeking to answer a question that could turn conventional wisdom on its head: Can tobacco cure cancer?
The plant best known for its negative health effects has been genetically engineered to create a drug comparable to Herceptin that could one day be used to treat highly aggressive breast cancers at a lower cost.
That development is part of a plant-based trend in pharmaceuticals. It is based on the belief that proteins can be made faster, cheaper and easier, allowing patients in remote parts of the world to gain access to medicines once unaffordable. And it’s not just tobacco. Plants being tested as biological drugs sound like they belong not in the laboratory but in the vegetable section at the health-food store: carrots for Gaucher’s disease, duckweed – those green flecks on top of ponds – to treat hepatitis C, and safflower to make insulin.
“One day we’re going to be able to grow these antibodies in plants like tobacco,” said Leigh Revers, the associate director of the master of biotechnology program at the University of Toronto. “…The question is can you make this drug identically the same as the other guy and prove it’s safe?”
Don Stewart, president and chief executive officer of PlantForm Corp. based in Guelph, Ont., whose company is running animal studies on tobacco, thinks so. The key, he said, is to remove sugars from the protein molecule, which can cause adverse side effects in humans, adding that using plants is a way of thinking “that’s enjoying a resurgence at the moment.”
In this case, the process takes place in Kentucky, where the tobacco is engineered, then cut and pounded with a giant screw, similar to those used in food manufacturing. From there, a pulp resembling crème de menthe is made; out of that extract, the drug is purified. It’s this act of purification that transforms it into a potentially cancer-curing drug.
A hearty plant with leaves the size of elephants ears, tobacco can be grown close together, inside a greenhouse or out. And it is not part of the food chain like corn, so there is no danger of viruses getting into the food supply.
“The beauty is being able to produce a very sophisticated protein-based drug in a bioreactor in a plant that basically requires fertilizer, water and sunlight,” said Michael McLean, director of research at PlantForm. “It’s as simple as possible for a manufacturing process.”
The developers have a long way to go – animal studies just began Jan. 26. Human studies with as many as 50 people aren’t slated to take place until late 2013, followed by a larger trial of up to 400 subjects in 2014. Still, Mr. Stewart believes the lower projected cost of the drug – $20,000 to $28,000 – will be attractive globally, something he will have to prove against four other competitors vying for that part of the cancer-treatment market.
Herceptin (the trade name for trastuzumab) is used to treat people with HER-2 positive breast cancer – about 20 to 25 per cent of breast-cancer patients. It has turned one of the most aggressive forms of the disease into one of the most treatable, though at a high cost: about $40,000 for a course of treatment, which consists of intravenous medication provided every three weeks for one year.
The drug comes off patent in Europe in 2014 and in North America in 2017.
Making a bio-similar drug is like making a generic – but not exactly: It isn’t a perfect copy like a chemically made compound, but it should come close and perform comparably well. While these types of drugs are intended to reach patients faster – it takes five to six years instead of 15 years to make a brand-name drug – their makers still must show that their product is safe and efficacious.
Typically, government regulators, which license and approve drugs, don’t look at how innovative the process is but merely whether the generic version looks the same under a microscope as the brand-name version. Herceptin is made in a bio-reactor from mammalian cells that have been originally derived from a Chinese hamster, not a plant.
“They have managed to engineer it so that it’s more human-like,” said Dr. Turner, who holds a PhD in chemistry. “It [tobacco] could be a great vehicle for producing all sorts of biological medicines, but I think it still could be 10 years away.”