Drugmaker Eli Lilly and Co. is stopping development of one of its potential Alzheimer's disease treatments in late-stage patient testing.

The Indianapolis company says early results from two studies of semagacestat show the treatment did not slow the disease's progression and was tied to some worsening clinical measures.

Lilly still has another potential Alzheimer's treatment in late-stage testing, and the drugmaker said this decision will not affect that drug.

Lilly will face the expiration of patents protecting several top-selling drugs in the next few years, and last week it learned a U.S. District Court judge ruled a patent protecting the attention deficit hyperactivity drug Strattera was invalid.

Shares of the drugmaker slipped 2.4 percent in premarket trading.