Mast Therapeutics has entered into a definitive agreement to acquire Aires Pharmaceuticals, a privately-held, clinical stage pharma company developing therapies to treat pulmonary vascular disorders. Aires’ lead product, AIR001, is a nebulized formulation of nitrite and has orphan drug status with the FDA and the EMA for the treatment of pulmonary arterial hypertension   Aires will become a wholly-owned subsidiary of Mast Therapeutics in exchange for shares of Mast common stock representin...