The best answer comes from the paper you cited earlier:
> "New biologic drugs are orders of magnitude larger than small-molecule drugs, and it’s often impossible to know on an atom-by-atom basis whether one large-molecule drug is the same as another. Subsequent versions of off-patent biotech drugs are therefore called biosimilar rather than generic. Differences in the tissue systems that produce them can lead to differences in protein folding and glycosylation, which could theoretically result in efficacy or safety differences. But the FDA, the EMA, and the generic drug industry hope these issues can be addressed by new regulatory sciences of biosimilarity."
> "Although regulatory pathways for biosimilar insulin are being finalized in the United States and Europe, economists warn that the introduction of biosimilars may not lead to price reductions equivalent to those seen with typical generic medicines. Even an abbreviated approval process for biosimilars will require substantially more original data than the typical abbreviated new drug application required for small-molecule generics and will necessitate immunogenicity and other safety studies in humans."
