April 13 (Bloomberg) -- Roche Holding AG sued Mylan Inc. to prevent it from selling a generic version of the Xeloda breast cancer treatment.

Mylan, the largest U.S. maker of generic drugs, is seeking U.S. Food and Drug Administration approval to sell a copy of Xeloda, whose active ingredient is capecitabine. Roche wants a court to block approval until a patent on the medicine expires in 2013.

Xeloda, approved as a treatment for breast cancer that has spread to other organs, generated 1.2 billion Swiss francs ($1.06 billion) in sales last year for Basel, Switzerland-based Roche. The drug also is used as a treatment for colon cancer following surgery.

Roche sued Canonsburg, Pennsylvania-based Mylan April 8 in federal court in Newark, New Jersey. The lawsuit will trigger an automatic period in which the FDA cannot approve Mylan’s application unless a court rules in the generic-drug company’s favor before then.

The case is Hoffman-La Roche Inc. v. Mylan Inc., 09cv1692, U.S. District Court, District of New Jersey (Newark).

To contact the reporter on this story: Susan Decker in Washington at sdecker1@bloomberg.net.

Last Updated: April 13, 2009 18:03 EDT