Although a major advance for biology, the problem with targeted, or homologous recombination was its very low efficiency in mammalian cells—only about 0.01 percent. But Maria Jasin, a molecular biologist at Memorial Sloan Kettering Cancer Center in New York, knew that rates were much higher in yeast. In 1994, her group tested the idea that introducing a break in both strands of DNA could trigger the cell to repair the break. Using a restriction enzyme called I-SceI, she found higher rates of recombination when she cut the DNA. Moreover, those breaks could be repaired with an exogenous piece of DNA. Jasin detected two different forms of DNA repair: homologous recombination and non-homologous end-joining (NHEJ). The former produced a clean repair, the latter a series of short deletions flanking the target site. Jasin’s demonstration that a double-strand break was “editogenic” was a major landmark, arguably the first gene-editing experiment, even though its significance was not truly appreciated for a decade. In the Old Testament of Genome Editing, Urnov calls this the “gospel according to Jasin.”5
“I am a textbook example of ‘right place, right time.’ My entire life!”6 I’ve managed to corral Urnov for an hour in a hotel lobby in Florence, Italy, to reflect on the Old Testament of genome editing.
Urnov was born in the former Soviet Union during the calm of the 1970s. Socialism more or less worked. Moscow was a cultural Mecca. Friends and families argued about the meaning of life at the kitchen table. His father was a literary professor, his mother a linguist. Both were published biographers. His grandfather had edited the works of Charles Dickens. Urnov grew up on the works of Lewis Carroll, Dickens and Twain, while becoming an obsessive Beatles fan. Although not a scientific household, Urnov’s father was friends with the family of the great Russian molecular biologist Vladimir Engelhardt, who lent him a copy of The Double Helix. Watson’s book had a profound effect on the fourteen-year-old Urnov, especially the “incomparable taste of having discovered a secret.” After one reading, any other career plans were canceled. He was hooked on DNA.
Urnov enrolled at Moscow State University in 1985, studying biology the year that Mikhail Gorbachev came to power. Glasnost was instituted in Urnov’s freshman year, perestroika in his sophomore year. The Chernobyl disaster in 1986 also had a major effect on him. By the time he graduated, the Soviet Union had essentially fallen apart. Going west would no longer mean being smuggled in a suitcase or emigrating via Israel. With his parents’ support, Urnov enrolled at Brown University. His PhD advisor, Sue Gerby, patiently domesticated the ex-Soviet into her lab, where he spent six years studying how genes turned on and off. At a conference, a “starstruck” Urnov asked Alan Wolffe if he could join his lab as a postdoc. Wolffe was dynamic, charismatic, and the youngest institute director ever at the NIH. He said yes.
Urnov was catapulted into the premier league of genetics research. Wolffe was an expert in the emerging field of epigenetics, the study of chemical modifications to DNA that regulate gene activity. Joining Wolffe’s lab reminded Urnov of the Red Queen’s race in Through the Looking-Glass, as Alice says, when we run this fast, we generally get somewhere else. Everybody in the lab was top-notch, working around the clock. He had to up his game and be ready when Wolffe ambled up to his bench and asked: “Ah, Dr. Urnov, what have you discovered?”
Alfred Hershey, one of the founders of molecular biology, once described “Hershey Heaven” as coming to the lab, running an experiment, and having it work every day. Urnov says he was “truly in Hershey Heaven.” But then in 2000, in a surprising move, Wolffe accepted an offer to head research at a young biotech company in California. At age forty, Wolffe was ready for a new challenge. Urnov readily agreed to go west. It was the first time he heard the name Sangamo.
The home office of Edward Lanphier, the retired founding CEO of Sangamo BioSciences, is a carriage house in Marin County, about ten miles north of San Francisco. I stop to admire the mementoes of a successful biotech career. A framed front page of the San Francisco Examiner from 1981 has the headline: GENENTECH JOLTS WALL STREET. A bookshelf houses the obligatory vanity license plate (“SANGAMO”) that Lanphier belatedly detached from his car. A framed photo shows Lanphier and his daughter in New York outside the Nasdaq stock exchange when Sangamo went public, the neon sign flashing his name.
I don’t have to look far for the origin of the company’s name: a Sangamo Electric meter has been converted into the base of a table lamp. In the 1890s, Lanphier’s great-grandfather, a Yale-educated electrical engineer, Robert Lanphier, cofounded a company in Sangamon County, Illinois. Lanphier designed and patented the watt-hour meter, with its familiar rotating wheel.7 Sangamo Electric became a public company before being acquired by Schlumberger in 1975. Lanphier asked his father if he could borrow the name and the logo for his own engineering start-up in the mid-’90s.
Lanphier got his start in the pharmaceutical industry in the early 1980s at Eli Lilly, which had just licensed recombinant human insulin from Genentech. In 1992, he joined Somatix, a “first-generation” gene therapy company. Three years later, Lanphier launched Sangamo, and soon became enamored with the potential of a class of gene regulators for gene therapy.
Zinc finger proteins (ZFPs) are an abundantI class of gene activators that were discovered a decade earlier by Nobel laureate Aaron Klug, a Lithuanian Jew who emigrated to England for his PhD and worked with Rosalind Franklin shortly before her death in 1958. These transcription factors had an unusual structure—a series of digit-like projections that make direct contact with the DNA. Each digit consisted of some thirty amino acids, anchored at the knuckle by a zinc atom binding to a quartet of amino acids. “Zinc structural domain” didn’t have much of a ring to it, so Klug coined the term “zinc finger” for each module. Further work showed each finger recognizes a specific three-base sequence of DNA, like a blind person reading braille. Thus, a DNA-binding protein containing three “zinc fingers” can recognize a specific nine-base stretch of DNA.
Sangamo’s initial goal was to use zinc finger proteins to switch certain genes on (or off). Lanphier approached the leaders in the field, including Carl Pabo at MIT. In London, he sat outside the office of Klug, who was president of the Royal Society, like a schoolboy waiting for the headmaster, before sealing a partnership over a three-hour lunch. Klug became a key advisor to Sangamo after selling his own company, Gendaq, to Lanphier in 2001. Sangamo also brought some biotech muscle onto the board, including Bill Rutter and Herb Boyer, cofounders of Chiron and Genentech respectively.
In 2000, Lanphier decided to ride the wave of irrational exuberance in the markets and go public, raising $150 million at the peak of the biotech bubble. To launch this new chapter, he lured Wolffe to become head of research. “It was an enormous coup,” Lanphier recalls. “Alan was just a frickin’ rock star” with an encyclopedic knowledge. “One of the most brilliant men I’ve ever known. Every brilliant, twentysomething alpha-male postdoc wanted to work for Alan.”8 Joining Urnov on the expedition was another Russian expat, Dmitry Guschin. Together with zinc finger designer Ed Rebar (from Pabo’s lab), Michael Holmes (from Bob Tijan’s lab at UCSF), Jeffrey Miller, and Andrew Jamieson, Sangamo assembled a boiler room of fearless young talent. Their mission was to take Sangamo, Lanphier said, “from the concept of a steam engine to an internal combustion engine to a freakin’ Ferrari.” The most critical hire was an English postdoc named Philip Gregory. “Amongst a group of unbelievably talented people, Philip organically rose to be the first amongst equals,” Lanphier said.