And especially something like psoriasis which is a genetic condition. It can't be cured without mitochondrial(gene) manipulation. Can 50% of the people be relieved of the symptoms? Sure, but even with no symptoms it's not cured. Can it go into recession permanently so it appears it's cured? You bet, but still not cured.
Like I said, I know of no FDA approved drug that claims it can cure X% of people of anything. May be wrong and if so I will readily admit to it if someone can find one.