People without orexin have narcolepsy. So the worry is could chronic use of an orexin antagonist cause narcolepsy symptoms? gsk had their own orexin in development but never got anywhere with it, so maybe that's why they were interested. I think it shows just how valuable a modestly promising, non cancer, phase III, NCE asset can be. There's surprisingly few out there. BTW: Heard the head of biology and head of chemistry at Sirtris left already. Not a good sign for gsk :) <!--Beg_Sig-->