(Reuters) – The U.S. Food and Drug Administration on Thursday approved three generic versions of Swiss drugmaker Novartis AG’s top-selling multiple sclerosis (MS) medicine Gilenya.

The approval allows HEC Pharm Co Ltd, Biocon Ltd and Sun Pharmaceutical Industries Ltd to produce the drug for the treatment of relapsing forms of MS in adult patients.

Novartis was defending patents on Gilenya in the United States to block generic rivals.

Earlier in June, U.S. federal court order had prevented rival generic makers from selling versions of Gilenya in the United States.

Nearly a decade after its U.S. approval, Gilenya remains Novartis’s No. 2 revenue generator at $829 million in the third quarter.

(Reporting by Dania Nadeem in Bengaluru; Editing by Shailesh Kuber)