Good question. I believe the standard of investigation remains the same, as thorough as possible, but it varies on the use of drug that is requesting approval. I have to ask is submittal of 1.7 million pages normal? Once the approval comes for glio, I believe it opens the floodgates for use on many other types of cancer, so I believe they are making sure the foundation is secure on which they plan to build future treatment approvals on.
But not being a doctor, I could be entirely wrong. Other than something is wrong, its the only explanation that makes sense to me.