definiens: Back - Up Compound " shall mean an active pharmaceutical ingredient Controlled by Amicus : ( i ) that is a Related Product for the same Target and disease within the Field as the applicable Terminated Product ( e.g., a Related Product described in Section 6.3.1(a ), if the Terminated Product was being Developed for Fabry Disease ) ; and ( ii ) that is either ( x ) referenced on Exhibit 6.4.4 hereto, ( y ) ( A ) for which Amicus has performed or is performing human clinical trials for such disease within the Field, or ( B ) for which Amicus first initiates such a human clinical trial within three ( 3 ) years after the date of such termination, or ( z ) a pre - clinical compound for which Amicus has performed at least one ( 1 ) study in an animal model in the Field that Amicus has not designated as a candidate for Development outside the Field