Shares of Arena Pharmaceuticals Inc. declined in Wednesday's extended session after the drug company posted quarterly results that fell short of expectations. Arena reported it swung to a first-quarter profit of $620.1 million, or $12.53 a share, from a loss of $32 million, or 80 cents a share, a year earlier. Revenue jumped to $801.1 million versus $1.8 million. First-quarter revenue was bolstered by $800 million associated with upfront payment from United Therapeutics. Anaysts surveyed by FactSet had forecast earnings of $14 a share and revenue of $802 million. Arena shares were down 2.6% after hours.