Shares of Regeneron fell nearly 9% on Tuesday after the U.S. Food and Drug Administration declined to approve a higher-dose version of the company’s blockbuster eye disease treatment.

The company was seeking approval for an 8-milligram dose of its injection, Eylea, for patients with wet age-related macular degeneration – the leading cause of blindness among the elderly – and two other eye diseases that are common in people with diabetes. 

Regeneron said the rejection was “solely due to an ongoing review of inspection findings at a third-party filler.”

The company did not provide further details on those findings or identify the third party, but said the decision was not related to the drug’s efficacy, safety, trial design, labeling or drug substance manufacturing. 

That suggests the drug could potentially win approval down the road. 

But a delay won’t help the company fight off threats to its Eylea drug franchise, which is facing competition from Roche Holdings‘ eye drug, Vabysmo. Roche’s treatment was approved last year.