A Johnson & Johnson building is shown in Irvine, California, U.S., January 24, 2017. REUTERS/Mike Blake

(Reuters) - A U.S. appeals court on Wednesday declined a request by Johnson & Johnson for a temporary restraining order blocking sales of generic versions of its blockbuster prostate cancer drug Zytiga from hitting the U.S. market.

The U.S. Court of Appeals for the Federal Circuit said it would not block Mylan NV and other companies from selling copycat versions of Zytiga while J&J seeks emergency relief at the U.S. Supreme Court.

J&J is seeking to undo a lower court ruling from October that invalidated a patent relating to Zytiga, opening the door for generic competition.

The Federal Circuit will hear J&J’s appeal of that lower court ruling on Jan. 24. On Tuesday, the Federal Circuit denied a request by J&J that it block sales until the appeal is decided.

Immediately after Tuesday’s ruling J&J said it would seek emergency relief from the Supreme Court, and sought a temporary restraining order blocking generic sales while it pursued that appeal.

Zytiga has been an important and still growing drug for J&J. Its sales jumped 43 percent to $958 million in the third quarter.

The entry of cheaper generic versions of Zytiga could also hurt sales of rival drug Xtandi, sold by Pfizer Inc and Japan’s Astellas Pharma Inc

J&J shares were down 3 percent at $141.97.