(Reuters) -The U.S. health regulator has declined to approve a higher-dose version of Regeneron Pharmaceuticals' eye drug Eylea, the company said on Tuesday, dealing a blow to attempts to defend the blockbuster treatment against a fast-gaining rival.
The Food and Drug Administration cited an ongoing review of inspection findings at a third-party filler of the higher dose for the decision.
Shares of Regeneron fell 7.8% to $723.2 in afternoon trading.
The complete response letter from the agency did not identify any issues with the drug's clinical efficacy or safety, trial design, labeling or drug substance manufacturing, and no additional clinical data or trials have been requested.
The company said it was working with the FDA and the third-party filler to bring the higher dose to patients as quickly as possible.
Eylea, which recorded $9.65 billion in global sales last year, has been hit since Roche's rival treatment Vabysmo was approved last year for wet AMD.
Regeneron was seeking approval for the drug to treat wet age-related macular degeneration (AMD), the leading cause of blindness among the elderly, and two eye diseases that are common in people with diabetes.
Analysts were expecting that some doctors could prefer higher-dose Eylea over a lower-dose version of the same drug or Roche's Vabysmo, as it would have a longer gap between injections in the eye.
Eylea is normally given in doses of 2 milligrams every eight weeks. Two late-stage trials had shown Eylea was as effective as the lower dose version when given at 8 milligrams at longer intervals without any additional safety issues.
The two trials included treatment of patients with wet AMD and diabetic macular edema (DME).
An estimated 1.1 million people in the U.S. have wet AMD, while 1.2 million are estimated to have DME, according to Regeneron.
Eylea is also likely to face competition from biosimilars late next year as some patents expire.
(Reporting by Raghav Mahobe and Khushi Mandowara in Bengaluru; Editing by Krishna Chandra Eluri, Maju Samuel and Sriraj Kalluvila)
