Jefferies analyst Eun Yang says pulmonary arterial hypertension experts see a low probability of success for United Therapeutics' FREEDOM-Ev interim analysis in September. Experts view success at interim analysis as "highly unlikely" and expect the study to continue to full analysis, Yang tells investors in a research note. She forecasts a compounded annual revenue decline of 8% for United Therapeutics thru 2021, versus the consensus at 5%. She also sees a lack of meaningful catalysts for the shares. Yang keeps an Underperform rating on the name with a $105 price target.