PRX-08066 is a selective and orally active 5-hydroxytryptamine receptor 2B (5-HT2BR) antagonist with a Ki of 3.4 nM. PRX-08066 inhibits the MAPK pathway, 5-HT release and fibrotic factor (TGFbeta1, CTGF and FGF2) expression. PRX-08066 inhibits the proliferation of KRJ-I cells and induces apoptosis (caspase-3 activation). PRX-08066 inhibits pulmonary vascular remodeling. PRX-08066 can be used of pulmonary Arterial Hypertension (PAH) and neuroendocrine tumor (NET)[1][2].