Engineered algae produce complex anti-cancer drug

Posted by Kate Taylor

Biologists at UC San Diego have genetically engineered algae to produce a complex and expensive human cancer treatment - raising hopes for the cheap mass production of this and other designer drugs.

The new technique could be far cheaper than the current method of using mammalian cells. It could even be used to make completely new complex designer drugs that can't be produced any other way.

"Because we can make the exact same drug in algae, we have the opportunity to drive down the price down dramatically," says Stephen Mayfield, a professor of biology at UC San Diego.

"You can't make these drugs in bacteria, because bacteria are incapable of folding these proteins into these complex, three-dimensional shapes. And you can't make these proteins in mammalian cells because the toxin would kill them."

Earlier this year, Mayfield was part of a team that developed a new kind of malaria vaccine.

"What the development of the malarial vaccine showed us was that algae could produce proteins that were really complex structures, containing lots of disulfide bonds that would still fold into the correct three-dimensional structures," says Mayfield.

"Antibodies were the first sophisticated proteins we made. But the malarial vaccine is complex, with disulfide bonds that are pretty unusual. So once we made that, we were convinced we could make just about anything in algae."

Now, the scientists have genetically engineered algae to produce a complex, three-dimensional protein with two 'domains' - one which contains an antibody, which can home in on and attach to a cancer cell and another that contains a toxin that kills the bound cancer cells.

Such fusion proteins are currently made by pharmaceutical companies through a complex process.

"We have a two-fold advantage over that process," said Mayfield. "First, we make this as a single protein with the antibody and toxin domains fused together in a single gene, so we only have to purify it one time. And second, because we make this in algae rather than CHO cells, we get an enormous cost advantage on the production of the protein."