Safety and tolerability of combination therapy with ambrisentan and tadalafil for the treatment of pulmonary arterial hypertension in children: Real-world experience

Abstract

Objective: To describe the safety and tolerability of treatment with ambrisentan and tadalafil in pediatric pulmonary hypertension (PH).

Study design: This retrospective observational two-center study included subjects (≤18 years of age) with PH receiving combination therapy with ambrisentan and tadalafil. Before initiating this therapy, many patients were on other therapies for PH. At baseline, patients either received no therapy or monotherapy with a phosphodiesterase 5 inhibitor (PDE5i) or endothelin receptor antagonist (ERA) (Group A), switched from a different PDE5i and ERA (Group B), or were on prostanoid therapy with or without a PDE5i and/or ERA (Group C and D). Demographics, symptoms, and adverse effects were collected. Pre- and postvalues for exercise capacity, hemodynamics, and biomarkers were compared.

Results: There were 43 subjects (26 F, 17 M) ages 4-17.5 years (median 9.3) with World Symposium of PH group 1, 3, and 5. Significant improvements were seen in change scores at follow-up in the entire sample and Group A for 6-min walk distance: +37.0 (6.5-71.0) [p = 0.022], mean pulmonary artery pressure: -6.0 (-14.0 to -3.5) [p = .002], pulmonary vascular resistance: -1.7 (-6.2 to -1.0) [p = .003], NT-proBNP -32.9 (-148.9 to -6.7) [p = .025]. WHO functional class improved in 39.5% and was unchanged in 53.5%; PH risk scores improved in 16%; were unchanged in 56%; and declined in 14%. Three patients discontinued therapy (two headaches, one peripheral edema). Seven patients were hospitalized for worsening disease (2/7 had a Potts shunt placed, 2/7 had an atrial septostomy). There were no deaths or lung transplantation.

Conclusions: Combination therapy with ambrisentan and tadalafil was well-tolerated, with an acceptable safety profile in a select group of children. This therapy was associated with improved exercise capacity and hemodynamics in children who were treatment naïve or on monotherapy with a PH medication before the initiation of ambrisentan and tadalafil. Based on these early data, further study of combination therapy in pediatric PH is warranted.

Keywords: ambrisentan; congenital heart disease; endothelin receptor antagonist; hemodynamics; pediatric cardiology; phosphodiesterase 5 inhibitor; pulmonary hypertension; tadalafil; targeted therapy.

Figure 1:

Patient Group Stratifications Based on Prior Targeted PH Therapies (n)

Figure 2:

WHO Functional Class at baseline and latest follow-up and ERS/ESC risk score at baseline and latest follow-up.

Figure 3:

Individual participant change in hemodynamic and exercise data between baseline and followup.%"* Individual participant change in mPAP (mmHg) between baseline and follow-up (median time of 21.5 months) (n=33, p=.002, (−14.0 – −3.5). Data are presented as Pvalue (95% CI).%"† Individual participant change in PVRi (Woods Units*m2) between baseline and follow-up (n=31, p=.003, (−6.2 – 1.0)). %"‡ Individual participant change in 6MWD (Meters) between baseline and most recent follow-up (median time of 21.5 months) (n=26, p=.022, (6.5 – 71.0)).