(Business 2.0) – Discovered just six years ago, RNA interference (RNAI) is now the "it" technology for drug development. RNAI works by destroying strands of messenger RNA responsible for producing harmful proteins. First used as a technique for evaluating drug targets, RNAI attracted more than $190 million in investments and research grants in 2004. Eli Lilly and Merck are both currently funding RNAI projects, partnering with startups to develop drugs for cancer and ophthalmic diseases. Pending approval, Acuity Pharmaceuticals, a small biotech startup in Philadelphia, will be the first to start RNAI clinical trials for age-related macular degeneration (AMD) this month. RNAI-discovered drugs for AMD, hepatitis C, and Lou Gehrig's disease should be in trials by the end of 2005. "Few technologies have this kind of potential," says Peter Barrett, a senior partner with Atlas Venture, whose $8.7 million investment helped biotech startup Alnylam Pharmaceuticals go public in May. "The only question is how big RNAI's impact will be." — BRIDGET FINN