Foster was unable to be licensed by an athletic commission, while Nijem is still medically suspended from his previous bout and did not receive clearance. MMAjunkie.com was first to report the news on Monday.
Foster had previously clinched a playoff spot with a third-round stoppage of Nijem at PFL 2 on June 21.
As a result, a 155-pound contest pitting Jason High against Johnny Case at PFL 7 on Thursday will determine the final entrant into the eight-man bracket. Thiago Tavares claimed the seventh playoff spot following the exit of Foster and Nijem.
High is 0-2 under the PFL banner, falling to both Natan Schulte and Efrain Escudero via submission in regular season bouts. Case, a six-time UFC veteran, is entering the lightweight field as an alternate. PFL 7 takes place at Ocean Resort Casino in Atlantic City, N.J. and airs on NBC Sports Network.
PFL 7 will be the organization’s final regular season event. The playoffs begin with PFL 8 on Oct. 5. The champion in each division at the conclusion of the playoffs will receive $1 million.