"Remission for a lifetime" IS a cure. We're in uncharted territory here. Let's assume for the sake of argument that Prurisol does clear up the psoriatic lesions. It's possible that it might last for a few months, or 6 months, or a year, and then another dosing regimen is needed.

But, continuing the speculation, let's say that it clears up the lesions totally (remission) and then 6 months later a new lesion appears. The patient could go back, get on the drug again, and hopefully jumping on it early would prevent a full-blown outbreak again.

At this point we just don't know anything, except that it appears to be safe in humans because we haven't heard of any serious adverse effects that are to the magnitude of halting the trial, and also we know that the animal trial didn't have any adverse effects on the animals -- except death, since they were "sacrificed" after the trial was over so that they could do necropsies. From the mouse's point of view that was pretty adverse .