Study Gauges Long-term Survival for PAH Patients on Opsumit

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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More than half of people with pulmonary arterial hypertension (PAH) who start daily treatment with oral Opsumit (macitentan) are expected to still be alive after nine years on the therapy, according to a new analysis of data from the SERAPHIN clinical trial and its open-label extension.

“These analyses provide important clinical insights into the long-term safety and tolerability for PAH patients receiving [Opsumit] 10 mg, with a follow-up period of up to 9 years,” its researchers wrote.

The team noted that this analysis “provides the longest follow-up for safety and survival published to date for any PAH therapy.”

The study, “Long-Term Safety, Tolerability and Survival in Patients with Pulmonary Arterial Hypertension Treated with Macitentan: Results from the SERAPHIN Open-Label Extension,” was published in the journal Advances in Therapy. The work was funded by Opsumit’s developer, Actelion Pharmaceuticals, a Janssen Pharmaceutical Company of Johnson & Johnson.

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Opsumit is an approved endothelin receptor antagonist that works by prompting blood vessels to relax and widen. The therapy’s safety and efficacy in PAH were demonstrated in the Phase 3 clinical trial SERAPHIN (NCT00660179), which enrolled 742 PAH patients ages 12 and up. Participants were assigned randomly to one of two doses of Opsumit (3 or 10 mg/day), or a placebo.

Results from the trial showed that Opsumit treatment significantly reduced morbidity and mortality outcomes.

Participants who completed the initial trial had the option to enroll in its open-label extension, SERAPHIN OL (NCT00667823). All 550 participants who entered the extension study were given Opsumit at the approved dosage of 10 mg/day. A total of 278 patients (50.5%) completed study treatment.

Participants’ mean age at the start of the extension study was 47.7 years, 80% were female, and about two-thirds also were receiving other PAH background therapies.

Survival outcomes were estimated based on data from all patients receiving 10 mg/day Opsumit in the main SERAPHIN study. Among these participants, the median follow-up time was just less than six years.

The estimated survival rates were 95% after one year, 84.0% at three years, 73.3% after five years, and 62.6% at seven years. At nine years, the estimated survival was 52.7%. The researchers noted that survival outcomes generally were better for patients with a lower baseline WHO functional class (i.e., less severe PAH at the study’s start).

“As most patients were receiving background therapy at the time of [Opsumit] initiation, these analyses help to further our understanding of the long-term benefit-risk ratio of using [Opsumit] combination therapy and provide survival estimates for the longest follow-up period to date for PAH patients treated with PAH therapy,” the researchers concluded.

Safety data from the SEPHARIN OL extension study were generally in line with the known safety profile for Opsumit. The most common adverse events reported were worsening PAH, upper respiratory tract infection, and peripheral swelling. Liver toxicity, a known potential complication of other endothelin receptor antagonists, were reported in fewer than 10% of patients.