Letairis (ambrisentan) is a safe pulmonary arterial hypertension (PAH) treatment, according to a confirmation of the clinical trial findings that led to its approval in Europe.
European regulators ordered the study to be on the safe side because of the trials’ small patient sample size.
In addition to confirming oral Letairis’ safety, the VOLibris Tracking (VOLT) study turned up the same adverse events as in the trials.
The European Union approved Letairis for PAH patients at low risk of liver damage after the clinical trials showed those who took it improved their six-minute walking distance, a measure of exercise capacity.
The limited trial participant size prompted the European Medicines Agency (EMA) to order a post-marketing study to confirm Letairis’ safety in a real-world population and to see if any previously unseen adverse events would surface.
VOLT (NCT00679224) was an observational, multicenter, post-marketing study that covered 999 patients at 115 centers in 15 countries in Europe, Canada and Australia. The patients took Letairis between 2008 and 2011.
PAH associated with connective tissue disease (PAH-CTD) was present in 238 of the patients. Two hundred twenty-two had had no prior PAH-specific therapy.
The study’s main yardstick was whether the level of aminotransferase enzyme would triple during the assessment. Aminotransferase, found mainly in the liver, is used to evaluate liver damage.
At the beginning of the confirmation study, 85% of the patients, or 845, were treated with 5 mg/day of Letairis, while 15%, or 150, received 10 mg/day. After the initial phase of the study was completed, the numbers changed to 63%, or 632, receiving 5mg and 36%, or 363, receiving 10 mg.
Before the study began, 49% of patients, or 486, had received no PAH therapy besides Letairis. Among those who had had received a previous PAH therapy, 330 stopped at least one of the medicines and switched to Letairis, while 322 continued receiving at least one therapy in addition to Letairis.
The most common adverse events among the 514 patients in the confirmation study were edema or fluid retention — 249 — and anemia — 143.
Overall, the study confirmed that Letairis was not associated with increased levels of liver damage in PAH patients and that the drug’s safety profile was similar to that in the clinical trials.