Saunders, 29, had been set to manage Isufi, 29, in Wembley for the WBO interim world belt on 13 April.
Former middleweight world champion Saunders came back into the ring in December following having a year outside during he failed a doping test.
He will grow to be a two-weight world winner if he wins.
Germany-based Isufi is undefeated at super-middleweight and it includes a listing of 27-3-2 together with 20 KOs.
Promoter Frank Warren said:”We’re stuck with no London place readily available in May, so we decided to think outside the box, go area to Bill and also bring the struggle into Stevenage FC.
“It’s a good facility which will have a 1012,000 convenience of boxing”
The belt has been vacated by current holder Mexico’s Gilberto Ramirez, who proceeded upto lightheavyweight, though there would be a unification bout if he returns into the division.