This follows my (limited) experience with biologic formulations.
Using large molecules presents enormous issues in even lab-scale production. All parameters are critical, especially temperature, as most proteins can irreversibly unfold at certain temps, and activity drops like a stone.
This can be accounted for in dose, but batches can have wildly different levels of activity and you don't know till you assay activity.
Assay is another clusterfuck. Much less robust than small molecule, and chain of custody and storage must be tightly controlled as well.
Thank you TG for distilling this data. The fact you can do it and they don't is quite telling.