Double agent: J. Christopher Anderson uses synthetic biology to sneak cancer-killing bacteria past the human immune system in order to attack tumors.
Marcus Hanschen

The big idea: J. Christopher Anderson is building a new version of E. coli and endowing it with special abilities: a sugar coating that acts as a cloaking device against the human immune system, a tool that busts through cell walls, a computer-like sensory system that locates tumors. The idea is to build a better bacterium—a germ designed to kill cancer—and it's one that takes a little getting used to. After all, E. coli is synonymous with food poisoning for most of us. "Bacteria get a bad rap," says the Berkeley bioengineering professor. "E. coli are people too, I like to say. There are good people and there are bad people. It's the same with bacteria."

The idea of using germs to fight cancer isn't new. The German scientist W. Busch first tried it in 1868 by moving a cancer patient into the bed recently vacated by a patient infected with flesh eating S. pyogenes. And it worked. Her tumor shrank to half its size. Then she died—killed by the cure.

Ever since, scientists have been looking for a bug strong enough to kill tumors, but not people. Although genetic engineering renewed hope that this would work, so far no one has found the sweet spot. Anderson's approach, developed with Christopher Voigt's UCSF lab and Adam Arkin's Berkeley lab, is to build a totally new bug—one attribute at a time. And he's recasting the problem to avoid the balancing act between killing the cancer and killing the patient. Instead of tweaking bacteria to grow better in tumors than in the bloodstream, he's building one that simply cannot multiply in the bloodstream. He's also installed a series of gadgets. The coat of sugars disguises the bacteria and keeps immune systems from recognizing them as outsiders. The sensory system allows the bacteria to identify tumors. Having found the tumors, the bacteria employ the third gadget, the invasion system (a technique borrowed from pathogens), to break through cell walls.

What's next: Anderson will begin testing his bug on mice early this year.