MSB to dispute FDA finding in Type A meeting, page-395

I believe they actually can, it’s called a confirmatory trial. It can be attached to full or accelerated approval.

The difference is the purpose of the confirmatory trial.. while subtle, it has a big impact on how the FDA would be judged if the confirmatory trial failed and how easily the FDA can force MSB to withdraw their product from market.

For accelerated approval the confirmatory trial is there to prove efficacy.

For a fully approved product, the confirmatory trial is there to provide technical support for efficacy and/or safety.

If an approved treatment’s confirmatory trial fails. then the FDA look very silly and may find it more difficult to force MSB to withdraw the product as they already have the FDA on record giving it full approval. The withdrawal clauses are likely to be a lot less onerous for fully approved products.

Whereas the withdrawal clauses are very clear for the accelerated approved products. No arguing with the FDA... it fails, you withdraw immediately.