SAN DIEGO, Oct. 2, 2018 — Arena Pharmaceuticals, Inc. (Nasdaq: ARNA) today announced positive data from a planned interim analysis of the ongoing open-label extension of the Phase 2 trial of its investigational drug candidate ralinepag, a next-generation, oral, selective and potent prostacyclin receptor agonist in development for the treatment of pulmonary arterial hypertension (PAH).