Eli Lilly and Co. said the U.S. Food and Drug Administration wants an additional three-year clinical trial before it will act on approval of its ruboxistaurin mesylate treatment for moderate to severe diabetic retinopathy.

Such a trial would take up to five years to complete, according to a spokesperson for Lilly, and the company said it is weighing options for further development of the treatment, which it had planned to market as Arxxant.

The FDA said it wanted additional data showing positive results before it would consider approving the drug.

Lilly said ongoing clinical trials for ruboxistaurin would continue while Lilly evaluates options for its further development.

"We still believe that ruboxistaurin has potential as a treatment for diabetic eye disease and are exploring the feasibility of further development of this molecule," Dr. John Lechleiter, Lilly president and chief operating officer, said in a statement.