ZURICH (Reuters) – U.S. regulators delayed a decision on Roche’s spinal muscular atrophy drug risdiplam, the Swiss drugmaker said on Tuesday, after the company submitted more data in February on the medicine against the genetic muscle-wasting disease.

Roche said the U.S. Food and Drug Administration will need longer than its original May 24 target date to review the new information. The new date is Aug. 24. Analysts have forecast risdiplam to eventually top $1 billion in annual sales, if it wins approval.

Basel-based Roche had been hoping to win a swift FDA blessing for the oral drug as it seeks to compete against Biogen’s Spinraza, the first SMA medicine, and Zolgensma, the gene therapy from Novartis that runs some $2.1 million per patient.

“In February 2020, based on discussions with the FDA, Roche submitted additional data,” Roche said in a statement. “Given the volume of additional data submitted, the FDA requires more time for review.”

The additional data Roche submitted included its SUNFISH Part 2 study of people aged 2-25 years with Type 2 or 3 SMA, forms of the disease that emerge later than the deadliest kind, Type I, but which still cause profound disabilities.

Roche, with its U.S. partner PTC Therapeutics, hopes the new submission helps it win approval for risdiplam to treat a broad range of patients, the Swiss company said.

(Reporting by John Miller; Editing by Tom Brown)