Exendin-4

The story usually gets told as a lone-genius triumph: a VA doctor finds a diabetes drug hiding in lizard venom. The truer version has an earlier layer. In the late 1980s, NIH biochemist John Pisano and gastroenterologist Jean-Pierre Raufman were already picking apart Gila monster (Heloderma suspectum) venom after noticing it set off strange activity in pancreatic tissue. Endocrinologist John Eng, at the Bronx VA Medical Center, ran with that thread — ordering dried venom from a mail-order Utah serpentarium catalog and, in 1992, isolating a brand-new 39-amino-acid peptide he named exendin-4 (Raufman was a co-author on the paper, so even the discovery itself was a team effort).

So why would a lizard carry a diabetes drug in the first place? Gila monsters are ambush predators built for feast and famine — they can gulp down a third of their body weight in a single meal, bank the fat in their tails, and then idle for months between dinners. Exendin-4 turned out to be the lizard's own version of GLP-1, the same gut hormone humans use to nudge insulin release after eating — except the reptile's version is far tougher, staying active for hours where ours breaks down in minutes. That freakish durability, evolved to manage a wildly irregular feeding schedule, is exactly what made it a viable drug: it lingers in the bloodstream long enough to actually work as a once- or twice-daily injection.

Then came the bureaucratic gut-punch. Because exendin-4 didn't treat anything specifically veteran-related, the VA's tech-transfer office refused to fund the patent, so Eng filed it himself in 1993 and absorbed the legal bills out of his own pocket for years while pharma companies shrugged at a diabetes peptide made from lizard spit. The break came at the 1996 American Diabetes Association meeting in San Francisco, where Amylin Pharmaceuticals' Andrew Young took notice, licensed the patent (developing it under the lab code AC2993), and later reimbursed Eng's costs. Eli Lilly came aboard in 2002 to bankroll the expensive late-stage trials a small biotech couldn't manage alone.

On April 28, 2005, the FDA approved synthetic exendin-4 — generic name exenatide, sold as Byetta — as the first-ever GLP-1 receptor agonist, an entirely new drug class rather than a tweak on an old one. Every GLP-1 that followed, from liraglutide to semaglutide (Ozempic and Wegovy) to tirzepatide (Mounjaro and Zepbound), descends conceptually from the mechanism Byetta proved out first. In 2013, Eng received the Golden Goose Award — a prize created specifically to honor federally funded research that looked obscure or even silly at the time, right up until it paid off enormously.