6zba Discovery and Early Clinical Development of Isobutyl 1-[8-Methoxy-5-(1-oxo-3 H -isobenzofuran-5-yl)-[1,2,4]triazolo[1,5- a ]pyridin-2-yl]cyclopropanecarboxylate (LEO 39652), a Novel "Dual-Soft" PDE4 Inhibitor for Topical Treatment of Atopic Dermatitis.