It's been a while since I looked into Horizant / xenoport, but from what I remember the research history on gabapentin enacarbil wasn't nearly as robust as it is for TNF-alpha.
From a quick read of the news, the FDA overlooked risks with gabapentin for seizures due to seizures being rather serious business. Restless leg syndrome isn't anywhere near the same level, and doesn't even approach life threatening. Pancreatic cancer is obviously a whole different ballgame.
An FDA denial would be bad news, sure, but I think you can line up a big list of reasons why horizant was denied that simply don't apply to TNFerade. Maybe a direct comparison isn't that helpful, but on virtually every level GNVC/TNF comes out looking like it has much better chances.