Britain's Billy Joe Saunders will give up his WBO world middleweight title "with a heavy heart" as he challenges the decision to deny him a licence, says promoter Frank Warren.
Saunders, 29, was refused a licence to fight Demetrius Andrade after returning an adverse finding in a Voluntary Anti-Doping Association test in August.
Warren says the boxer will give up his belt because of the "mental anguish".
He added the licence decision would be challenged in court.
"Billy Joe will, with a heavy heart, relinquish his world title while this issue is being resolved," Warren said.
Saunders, who was due to fight Andrade in Boston on 20 October, returned an adverse finding for the stimulant oxilofrine, which Warren says was in a "common decongestant nasal spray".
Saunders has insisted he is a "clean fighter to the bone".
Under World Anti-Doping Agency (Wada) and UK Anti-Doping (Ukad) rules, oxilofrine is only banned in competition. That means a fighter is in breach of the regulations only if it is found in their system on the day of a bout.
But it is prohibited at all times by the Voluntary Anti-Doping Association, which tested Saunders on 30 August.
Warren says it was "not a failed test" because the Massachusetts State Athletic Commission (MSAC) - which is responsible for issuing a licence to fight in Boston - did not follow Wada's rules.
After taking the case to the Supreme Court, Warren said he would begin legal proceedings against the MSAC.
When BBC Sport contacted the MSAC, it confirmed that Saunders was refused a licence because oxilofrine is on Wada's banned list but it made no distinction between in and out of competition.
In September, Saunders was fined £100,000 by the British Boxing Board of Control for misconduct after a video was posted on social media in which the fighter offers a woman £150 worth of drugs to perform a sex act. Saunders apologised for the video and described it as "banter" that "went wrong".