There is no known cure for ghoulification.

We’ve not seen it in game, but I am convinced there is an Escape from LA style Surgeon General of Beverly Hills type character, cannibalizing body parts from captured victims to graft on well to do ghouls. The comedy of vanity taken to the extreme and body horror is too much to pass up. Plus, how cool would it even be if Bruce Campbell had a cameo?

Also if there was no way to become human again would the drug that hancock used to become a ghoul make it where he can't become feral. and how come eddie winter hasn't became a feral ghoul