United Therapeutics, headquartered in Silver Spring, Maryland, announced that the FDA has accepted its New Drug Application for ralinepag, an investigational once-daily oral treatment for pulmonary arterial hypertension (PAH), setting a Prescription Drug User Fee Act target action date of June 24, 2027. Chairperson and CEO Dr. Martine Rothblatt tied the filing to the disease’s severity: “Ralinepag has the potential to make an important difference for adults living with PAH, a complex, progressive, and life-threatening disease that can severely impact daily life and lead to right heart failure. With the NDA now accepted for review, we are one step closer to offering PAH patients a new, once-daily oral treatment.” She added that the clinical results underpinning the filing were substantial: “In our clinical trial, ralinepag delayed disease progression, achieved clinical improvement, and provided durability of effect over many years. We attribute these robust results to its unique chemistry and multi-pathway effects, including vasodilation and anti-proliferative and anti-inflammatory activity.”
What the Clinical Data Actually Showed
The NDA rests on the Phase 3 ADVANCE OUTCOMES trial, an event-driven, multicenter, global, randomized, double-blind, placebo-controlled study that enrolled 687 PAH patients, randomized 1:1 to ralinepag or placebo on top of standard-of-care background therapy. The trial’s primary endpoint, time to first adjudicated clinical worsening event, covered a composite of death, non-elective hospitalization for worsening PAH, initiation of parenteral or inhaled prostacyclin therapy, disease progression, or an unsatisfactory long-term clinical response. Ralinepag reduced that risk by 55% compared to placebo, a hazard ratio of 0.45 with a 95% confidence interval of 0.33 to 0.62 and a p-value below 0.0001, alongside a 47% improvement in the odds of achieving clinical improvement. Patients on ralinepag also saw reduced NT-proBNP levels, a biomarker of heart strain, and improved six-minute walk distance, a standard measure of exercise capacity in PAH trials, with results holding up consistently across patient subgroups. The full trial results were published in The Lancet in July 2026, giving this data an independent, peer-reviewed layer of scrutiny beyond the company’s own announcements.
How Ralinepag Is Designed to Work, and Why the Once-Daily Dosing Matters
Ralinepag is a selective prostacyclin receptor agonist with vasodilatory, anti-proliferative, and anti-inflammatory effects, and the company says it carries roughly six times the binding affinity of selexipag’s active metabolite, one of the existing oral therapies in this drug class. If approved, United Therapeutics says ralinepag would be the first once-daily oral prostacyclin agent available for PAH, a meaningful distinction in a treatment landscape where many existing prostacyclin therapies require multiple daily doses or continuous parenteral or inhaled delivery, both of which carry a heavier burden for patients managing a chronic, progressive disease.
A Drug United Therapeutics Bet Big on Nearly a Decade Ago
Ralinepag isn’t a United Therapeutics-originated molecule. The company licensed global rights to it from Arena Pharmaceuticals in a deal announced in November 2018 and closed on January 24, 2019, paying $800 million upfront with a total potential value exceeding $1.2 billion once regulatory milestones and tiered royalties are factored in. That upfront price tag made it one of the larger licensing bets in pulmonary hypertension drug development at the time, and this FDA filing acceptance, nearly eight years later, is the clearest sign yet that the wager is approaching a real commercial test. United Therapeutics is headquartered in Silver Spring, Maryland, within the BioHealth Capital Region, with additional operations in Research Triangle Park, North Carolina, and the company has built much of its identity around treating rare and life-threatening diseases like PAH, a mission Rothblatt has said traces back to her own daughter’s diagnosis with the condition.
