Ralinepag Lowers PAH Clinical Worsening Risk in Trial

An international phase III clinical trial has shown that oral ralinepag can significantly lower the risk of a first clinical worsening event in patients with pulmonary arterial hypertension, or PAH. These patients were already receiving contemporary background therapy when they entered the study. The main findings were presented earlier this year at the annual meeting of the American Thoracic Society. Following the promising data, United Therapeutics, the manufacturer of ralinepag, submitted a new drug application to the U.S. Food and Drug Administration last month.

Design of the ADVANCE OUTCOMES Study

The trial, known as ADVANCE OUTCOMES, enrolled participants over a period from 2019 to 2025. Each individual was randomly assigned to receive either ralinepag or a matching placebo. Those in the ralinepag group started with a dose of 50 micrograms taken once per day. The dose was then gradually increased on a weekly basis through a process called titration. The goal was to reach the highest dose that each person could tolerate without unacceptable side effects. According to the research team led by Humbert, the median doses at week 28 and week 52 were 250 µg and 300 µg daily, respectively. After reaching their individual doses, patients were followed for a median duration of 85 weeks in the ralinepag arm and 78.4 weeks in the placebo arm. This careful methodology ensured a robust evaluation of the drug’s effects.

Defining the Primary Endpoint

The primary endpoint of the study was the time to the first occurrence of a clinical worsening event. The investigators defined this composite endpoint to include several severe outcomes. Death from any cause was one component of the endpoint. Hospital admission due to worsening PAH or right heart failure was another. The need to start parenteral or inhaled prostacyclin-pathway therapy also counted as an event. Additionally, disease progression and an unsatisfactory long-term clinical response were included. This broad measure was intended to capture the multifaceted nature of PAH deterioration.

Efficacy Results: A Significant Reduction

When the data were analyzed, ralinepag demonstrated a notable reduction in the composite endpoint. The study population consisted of pretreated patients who were classified as low- or intermediate-to-low risk. Most of these individuals were already using two background therapies for PAH. In this group, the event rate was 18% for those on ralinepag, compared to 36% for those on placebo. This difference yielded a hazard ratio of 0.45, indicating a substantial risk reduction. The 95% confidence interval for this hazard ratio ranged from 0.33 to 0.62, underscoring the statistical strength of the finding. Moreover, the treatment effect was consistent across all prespecified subgroups that were examined. These results highlight the potential of ralinepag as a meaningful new option for PAH management.

Adverse Events and Tolerability

Despite the clear efficacy benefits, ralinepag was associated with a higher rate of treatment discontinuation prompted by side effects. The most commonly reported adverse events were headache, diarrhea, nausea, and myalgia. These side effects are familiar to physicians who treat PAH, as they are characteristic of drugs acting on the prostacyclin pathway. The safety findings from the trial align with expectations for this class of medications. Monitoring during the study confirmed that tolerability remains a challenge, although the benefits may outweigh these issues for many patients.

Continuation in an Open-Label Extension

To provide ongoing therapy, the trial protocol offered an open-label extension study. Patients who completed the main trial as well as those who experienced a clinical worsening event were permitted to enroll. In this extension, all participants receive active ralinepag. This arrangement not only allowed continued access to the drug but also may generate longer-term safety data.

Regulatory Status and Unanswered Questions

A noteworthy limitation of ADVANCE OUTCOMES is its use of a placebo comparator. This design choice means that the study cannot determine how ralinepag compares in terms of efficacy or tolerability to other approved prostacyclin-pathway therapies, such as selexipag. Consequently, the exact position of ralinepag in the treatment algorithm for PAH remains unclear. Despite this, the strength of the trial data has already led to a regulatory submission. If the FDA approves ralinepag, it could become a new oral choice for managing this serious condition. As with any medication, patients are advised to discuss the potential benefits and risks with their healthcare provider.

Source

• www.medpagetoday.com
• The Lancet (www.thelancet.com)
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