After a drug test, Josh Quinlan was not allowed to fight in UFC Vegas 59.

A pre-fight drug test of UFC welterweight Josh Quinlan revealed a trace amount of an infamous metabolite of oral turinabol, prompting the Nevada Athletic Commission to decline clearing him for a bout with Jason Witt at UFC Vegas 59, the UFC said in a statement.

Quinlan was successful in weighing-in for Saturday’s event. But according to a statement from the UFC, the promotion was notified by its drug testing partner, U.S. Anti-Doping Agency, that a “recent” urine sample he submitted contained “a small amount” of the M3 metabolite of dehydrochloromethyltestosterone (DHCMT), which is a part to the oral steroid that’s ensnared several UFC fighters.

USADA modified its UFC drug testing program to allow up to 100 picograms of M3 in a sample before it was determined to be adverse result subject to an anti-doping penalty. But according to the UFC, the commission “ruled that Quinlan is not cleared to fight” and cancelled the bout. The NAC didn’t immediately respond to a request for comment on the UFC’s statement.

The UFC announced that the UFC San Diego has moved the UFC welterweight bout to UFC San Diego. It will take place at Pechanga Arena, San Diego.

The UFC has identified the M 3 Metabolite in several fighters. The most notable being Jon Jones (former UFC lightweight champion), who was found to have trace levels of this chemical during drug testing related to his fight with Alexander Gustafsson in UFC 232..

Jones’ seesawing results were attributed to increased sensitivity in testing methods, and after an extensive review, USADA determined that the amount wasn’t performance-enhancing and declined to discipline him. USADA, UFC and the NAC subsequently modified their rules to keep athletes from being flagged for the hard-to-clear metabolite, which frequently “pulsed” over time and possibly as a result of weight-cutting. The modified rules didn’t allow Flyweight Manel Kae to test positive for the metabolite during a UFC Vegas 52 fight. However, he was not sanctioned.

In cases where adverse or atypical drug test results arrive close to an event, the NAC has erred on the side of caution, declining to clear fighters until it can verify what happened and make an appropriate licensing decision in the future.