United Therapeutics Gains Global Rights to Potential PAH Therapy Ralinepag

United Therapeutics has now acquired worldwide rights over ralinepag, a potential oral medication under Phase 2 and 3 clinical testing for pulmonary arterial hypertension (PAH), the company announced in a press release.

Ralinepag was discovered and first developed by Arena Pharmaceuticals. In November 2018, Arena and United Therapeutics reached a licensing agreement, which now goes into effect, after the termination of a required waiting period.

Under the agreement, United Therapeutics obtained the exclusive, global rights from Arena to develop and produce ralinepag. In return, Arena received an upfront cash payment of $800 million, and may earn up to $400 million more if certain regulatory milestones are achieved, in addition to royalties on ralinepag sales.

Ralinepag (APD811) is a next-generation, oral medicine that mimics the action of prostacyclin, a natural, potent vasodilator (a widener of blood vessels) produced by cells that line the walls of blood vessels. Like prostacyclin, ralinepag is a vasodilator. It can also inhibit the overproliferation of muscle cells surrounding blood vessels, as well as the clumping of platelets — two features that also contribute to PAH development. 

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Those characteristics, “combined with an extended half-life, support its application as a potentially best-in-class agent for the treatment of PAH,” Arena states in a release on its website. An extended half-life means the medicine is able to stay longer in the human body, potentially prolonging its therapeutic effects.

Following promising safety and efficacy results from a Phase 2 trial (NCT02279160) and an extension study (NCT02279745) — showing that ralinepag can improve a patient’s exercise capacity and blood flow in lung arteries, and that it has an overall good safety profile — Arena has begun a Phase 3 trial called ADVANCE OUTCOMES (NCT03626688).

This randomized, placebo-controlled trial’s objective is to determine the efficacy and safety of ralinepag when added to standard PAH treatments or PAH-specific background therapies. Its primary outcome measure will be time to a clinical failure, defined as hospital admission due to worsening PAH, disease progression, unsatisfactory long-term clinical response, or death.

The study expects to recruit an estimated 700 participants with PAH, and is currently enrolling at several centers in the U.S. More information on contacts and locations is available here.