Additional Relevant Details The LIBERTY study will evaluate the effects of ubenimex added to current standard of care in patients with pulmonary arterial hypertension (PAH). Despite multiple approved vasodilator therapies, PAH remains a progressive, life-threatening cardiovascular disease.  Ubenimex is a well-characterized, oral, small-molecule inhibitor of leukotriene A4 hydrolase, which blocks the production of leukotriene B4 (LTB4), an inflammatory mediator implicated in PAH disease.