T. De Marco

Association of CYP2C9*2 With Bosentan‐Induced Liver Injury

Bosentan (Tracleer) is an endothelin receptor antagonist prescribed for the treatment of pulmonary arterial hypertension (PAH). Its use is limited by drug‐induced liver injury (DILI). To identify genetic markers of DILI, association analyses were performed on 56 Caucasian PAH patients receiving bosentan. Twelve functional polymorphisms in five genes (ABCB11, ABCC2, CYP2C9, SLCO1B1, and SLCO1B3) implicated in bosentan pharmacokinetics were tested for associations with alanine aminotransferase (ALT), aspartate aminotransferase (AST), and DILI. After adjusting for body mass index, CYP2C9*2 was the only polymorphism associated with ALT, AST, and DILI (β = 2.16, P = 0.024; β = 1.92, P = 0.016; odds ratio 95% CI = 2.29−∞, P = 0.003, respectively). Bosentan metabolism by CYP2C9*2 in vitro was significantly reduced compared with CYP2C9*1 and was comparable to that by CYP2C9*3. These results suggest that CYP2C9*2 is a potential genetic marker for prediction of bosentan‐induced liver injury and warrants investigation for the optimization of bosentan treatment.

An observational study of inhaled-treprostinil respiratory-related safety in patients with pulmonary arterial hypertension

Inhaled treprostinil (Tyvaso) has been shown to be a safe and effective addition to pulmonary arterial hypertension (PAH) oral therapies; however, the respiratory-related safety profile of inhaled treprostinil required further elucidation in the setting of routine clinical care. The objectives of this study were to characterize respiratory-related adverse events (AEs) associated with current or recent treatment with inhaled treprostinil and to compare the incidence of respiratory-related AEs in PAH patients treated with inhaled treprostinil with that in patients treated with other Food and Drug Administration (FDA)–approved PAH therapies. This was a long-term, prospective, observational study. All respiratory-related AEs were recorded during the study. The number of PAH patients enrolled was 1,333, 666 treated with inhaled treprostinil and 667 controls (treated with an FDA-approved PAH therapy other than inhaled treprostinil), for a total of 958 and 1,094 patient-years of exposure, respectively. In the inhaled-treprostinil group, 1,281 respiratory-related AEs were reported in 403 patients (61%), and in the control group, 1,295 respiratory-related AEs were reported in 388 patients (58%). Cough, throat irritation, nasal discomfort, and hemoptysis were the most common respiratory-related AEs (occurring in ≥2% of patients in either treatment group) that demonstrated a higher number of events per patient-year of exposure in the inhaled-treprostinil group than in the control group (risk ratio [95% confidence interval]: 1.487 [1.172–1.887], 3.777 [2.050–6.956], 2.039 [1.072–3.879], and 1.957 [1.024–3.741], respectively). Overall, inhaled treprostinil was well tolerated by PAH patients in routine clinical care, with respiratory-related AEs consistent with the known safety profile (trial registration: clinicaltrials.gov identifier: NCT01266265).