GSK doesn't have a case, since Lovaza's "moiety" is NOT the EPA molecule. It is BOTH the EPA and the DHA molecules.
(Of course, GSK could try to prove Lovaza's "moiety" is JUST the EPA molecule alone; but that will take some time. And the giant might also have to do away with the DHA molecule in its pill, literally, or medicinally declaring it to be an non-active ingredient... then, yes, Lovaza would be just another Vascepa.)
But Vascepa's "moiety" is just the EPA molecule alone. There is actually a good reason why introductory logic needs to be taught in all colleges.
I forgot one thing. GSK would have a case, IF the FDA were to change its "moiety" definition... changed it to something like:
"an active moiety is ANY molecule or ion in the drug; it doesn't matter which one --- if a drug has more than one molecule or ion --- if it is in the drug, it may be considered the MOIETY that determines the action of the drug."