Amonafide interferes with the DNA breakage-reunion activity of mammalian DNA topoisomerase II resulting in DNA cleavage stimulation. [2] Compared with those of other antitumor drugs, Amonafide-stimulated cleavage intensity patterns are markedly different. Amonafide highly prefers a cytosine, and excludes guanines and thymines instead, at position -1, with lower preference for an adenine at position +1.