Arena Pharmaceuticals Inc. shares jumped 35% in late trading Monday after the company announced positive results from a drug study. The San Diego company said that a phase 2 study of a drug targeted at pulmonary arterial hypertension, a disease that causes high blood pressure in the lungs, showed "a statistically significant absolute change from baseline." In a study of 61 patients, those that received the drug, called ralinepag, showed 29.8% greater improvement than patients in a placebo group and 20.1% improvement compared with the baseline, the company said. Arena stock topped $25 in after-hours trading immediately following the announcement, after closing with a 4.5% decline at $18.39; Arena shares have not hit $25 in regular trading since 2015. Arena planned a conference call to discuss the results for 4:30 p.m. Eastern time Monday.
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