Eli Lilly shares slipped Friday morning after regulators said they need to see more data on the company's application for a quick approval of its potential Alzheimer's disease treatment.
Lilly said the Food and Drug Administration wants information from at least 100 patients who received a minimum of 12 months of continued treatment on donanemab. The drugmaker gave the update after markets closed Thursday.
The potential treatment aims to clear a plaque from the brain that is a key hallmark of the mind-robbing disease.
Lilly said it had more than 100 patients in the study used for its accelerated approval application. But many were able to stop taking the drug as early as 6 months into treatment due to the reduction in plaque.
The FDA's accelerated approval program allows drugs to launch in the U.S. based on promising early results, before they're a confirmed benefit to patients. The agency granted accelerated approval earlier this month to another Alzheimer's drug, Leqembi from Japan's Eisai.
Lilly is still seeking full approval for its drug. The company expects to report early results from a late-stage study in the second quarter.
SVB Securities analyst David Risinger called the accelerated approval delay "immaterial." He said in a research note that the drug's sales prospects depend more on the late-stage study the drugmaker is wrapping up.
Shares of Indianapolis-based Eli Lilly and Co. slipped by about $5, or 1%, to $346 before markets opened Friday.