Why are biogenerics so hard to regulate?

There’s been a lot of press floating around lately about the push to develop a framework for biogeneric (or biosimilar, or follow-on, etc.) approvals.

Why are biogenerics so hard to regulate? Why can’t they just follow the same path as traditional generic drugs? The answer lies in their size and complexity. I’ll use the following excerpt from my book:

Source: Building Biotechnology

The difference between traditional drugs (typical of traditional pharmaceutical techniques) and biologic drugs (typical of biotechnology techniques) is illustrated in Figure 4.1. Aspirin is very small. Erythropoeitin (Epogen) is more than 500 times larger than aspirin. This size difference alone makes it difficult to determine that a generic version of erythropoeitin produced by a second party is identical to a version produced by an innovator. Furthermore, biologic compounds can undergo subtle modifications which are currently very difficult to detect.

In order to gain approval, traditional generic manufacturers must demonstrate their their drugs are chemically identical to pioneer versions and exhibit the same properties in the human body as the original drugs do. How can you do this for biogenerics? Well, you can’t. It’s currently not possible to demonstrate that a second-source biologic drug is identical to an innovator’s drug. That’s why the path to biologic generics is likely going to involve abbreviated clinical trials and it’s why the resulting generics will likely exhibit slightly different properties than the original drugs. Because of these differences, biogenerics won’t be as relatively cheap as traditional generics are, and they’ll face an extra burden to demonstrate that they are as safe and effective as the established branded drug they’re competing with.