Sanofi has to show that their process is reasonably the same as that which was approved. There is no reason to assume they have to be able to characterize Lovenox to any substantial degree. Furthermore, I seriously doubt they did characterize to anywhere near the degree the FDA now expects.
A generic can not possibly match the S-A process, so they have the much harder path of proving the output is the same.
EDIT: If somebody wants to run trials and create a branded generic then that could easily be done w/o infringing.
But maybe there is some way to do this while avoiding the patent - Sanofi is proof that this is possible.
A long winded analogy given the fact that much of the manufacturing process for Lovenox has many more aspects of black box and magical elves than most drugs.
Sanofi -
Managed to round up a group of magical elves that create a really nice car. Sanofi knows it is nice because they have some test drivers drive it around and rate it. But they don't really know how to know it got that way - just that a special bunch of elves in a black box can make it that way most of the time (e.g. if you feed them right and don't piss them off by banging on the box or playing with the lights). Nor do they even know for sure how the car works. But FDA wants to know with high reliability that every car is safe and not a lemon. What to do? What to do? Well, Sanofi decides to monitor 20 things they do know how to monitor - the food that goes into the box, whether the car comes out with wheels, ... and they correlate those things with exhaustive testing and find that if they monitor just 7 things the test drivers don't die too often. But if they could see into the black box they would know that the only reason they need to monitor only 7 things is that there are just 7 elves of importance. Thus, because elf number 1 works on both tires and steering you can be confident that if you check tires the steering will work.
The FDA's problem is that Momenta may not be using the same 7 types of elves. Maybe they are siblings or cousins - but not the same. And they divide up the work differently. It is 8 elves and the elf working on tires is NOT the same elf working steering so checking tires may not be adequate. Not only that a generic is supposed to be 'the same' and thus, by definition, has to check more things.
Thus what works for Sanofi is not likely to be acceptable for generics.
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