I believe that if the FDA were deaf, dumb, and blind they'd still see the benefits of having DCVax-L available is worthwhile, even if it meant stretching one or more of their rules. This will be even more apparent if those in the UK, and perhaps Europe and/or Canada are clearly seeing the benefits of the vaccine.
I frankly don't believe the FDA will have to stretch there rules at all. I believe that back when the trial was first defined, and when the FDA wanted the cross-over for people deemed to have progressed, they had a way established to evaluate OS that didn't involve the control group, which would no longer exist because they largely crossed over. At that time the FDA may not have had much guidance about it, but that was being developed. At that time no one knew about pseudoprogression and how it would invalidate a goal based on progression, but when that became clear, and after a halt where changes were made, that was acceptable to all four regulators, not just the FDA.
I believe the FDA is a very different entity than it was nearly two decades ago when the trial was initially designed. Dr. Padzur is still there, but much of his thinking has changed both based on directions from above, and especially on the death of his wife to cancer. I certainly don't believe he's changed completely, but I don't believe his actions will delay drug approvals as much where new trials are required, rather they'll get conditional approvals until confirming trials remove those conditions. I expect that many trials will be initiated once DCVax-L is approved, but I doubt if more GBM patients will be involved, except where other products are added, but many trials will be initiated in other cancers to prove the vaccine is truly tumor agnostic.