Folate is Gr-r-reat!
Endocyte's Christopher Leamon found a promising cancer treatment on the side of a cereal box.
By Siri Schubert

(Business 2.0) – History is littered with those who didn't get proper credit for furthering human knowledge. Rosalind Franklin helped Watson and Crick discover DNA, and Milton Humason developed techniques that let Hubble theorize about the Big Bang. If Endocyte's cure for cancer pans out, add Tony the Tiger to the list.

Endocyte VP for research Christopher Leamon initially wanted to be a doctor. But in 1986, when he was a premed student at Purdue University, his mother died of cancer. "Seeing how sick she felt from the chemotherapeutic drugs changed my life," he says. Dedicating himself to finding a treatment with less debilitating side effects, Leamon entered Purdue's Ph.D. program in chemistry instead of medical school.

He soon learned that inspiration doesn't always come quickly. Even back then, scientists were exploring targeted therapy—using molecules that tumors absorb as Trojan horses to deliver lethal drugs. Knowing that others had used the vitamin biotin as a carrier to insert proteins into plant cells, Leamon tried to duplicate the result in animals. But after nine months of research, he'd gotten nowhere. "It was a total failure," he recounts.

Then, about 6:30 on a fall morning in 1989, still exhausted from a long night in the lab, Leamon sat with his wife at the small wood breakfast table in their student apartment. A longtime cereal lover, he reached for a box of Kellogg's Frosted Flakes. While chomping, Leamon scanned the ingredients panel. In addition to milled corn and sugar, he found a long list of vitamins: ascorbic acid (C), niacinamide (B3), riboflavin (B2), thiamin hydrochloride (B1), and folic acid (B9). Leamon scribbled the list on a notepad and ran to the library. And there it was: a paper describing how folic acid—known in its naturally occurring form as folate—enters a human cell. "I knew this was it," Leamon recalls. Two years later, Italian researchers discovered that certain cancer cells carry special receptors for ingesting folate.

After developing a technique for attaching drugs to folate, Leamon observed that some malignant cells not only ingest the vitamin but also store it on their outer membranes for future use. That allowed him to mark cancer cells with chemical flags so immune systems can fight tumors the way they battle infections. Purdue patented the use of folate for targeted therapy, then licensed it to a nearby company called Endocyte, which Leamon joined in 1999. Endocyte has garnered $32.9 million in grants and investment, and tests of its proprietary therapy in mice have been promising: The rodents' immune systems fight cancer cells and also show resistance to new cancer injections. If human trials go according to plan, Leamon hopes to have a drug on the market by 2007 to treat ovarian, kidney, and breast cancers (in which folate receptors are most common). Of course, companies like AstraZeneca, Genentech, and Novartis are also developing targeted therapies, so Leamon keeps his pad of paper close at hand. "There are lots of 'Eureka!' moments in the lab," he says. "None as great as the one with folate, though. That breakfast redefined my career, and my life." — SIRI SCHUBERT