As mentioned above such an approach is not valid for follow-on versions of NBCDs. The classical generic approach disregards the complexity of NBCD compounds (pharmaceutical and biodistribution aspects) as they cannot be fully characterized in vitro, which is a prerequisite for the generic approach to predict pharmaceutical (quality) equivalence.[1][10] The reason is the complexity and the non-homologous composition of these synthetic large molecular products. Even slight differences in manufacturing might result in therapeutic or safety differences not to be attributed to a known or defined component.