LOS ANGELES: The much-anticipated rematch between Lamont Peterson and British boxer Amir Khan has been cancelled after the American failed a drug test, Golden Boy Promotions announced on Wednesday.Peterson and Khan's May 19 bout in Las Vegas was scrapped because the WBA and IBF light-welterweight champion tested positive for synthetic testosterone on March 19, reports said.Golden Boy said the failed drug test, combined with the Nevada Athletic Commission's "inability to hold a formal hearing" in time, led to the demise of the fight.Peterson won their first bout in Washington in December but the split decision was controversial. He won 113-112 on two judges' scorecards while the other had Khan a 115-110 winner. (AFP)