Efficacy and Safety of Ambrisentan in Children 8-18yrs

Pulmonary arterial hypertension (PAH) is a rare, progressive, highly debilitating disease characterized by vascular obstruction and the variable presence of vasoconstriction, leading to increased pulmonary vascular resistance and right-sided heart failure. If left untreated, PAH ultimately leads to right ventricular failure and death; adult subjects have a median survival of 2.8 years without treatment. Epidemiological estimates vary but prevalence in Europe is thought to be of the order of 15 cases per million. Large scale epidemiology studies of PAH in children have not been conducted and there is no or limited outcome data in pediatric PAH patients. A register in France (1995-1996) estimates the prevalence in children is as low as 3.7 cases per million. In a national, comprehensive country wide survey of the epidemiology of idiopathic PAH (IPAH) management and survival in the United Kingdom (UK) the incidence was 0.48 cases per million children per year and the prevalence was 2.1 cases per million children. Ambrisentan (VOLIBRIS™ tablets) is an endothelin receptor antagonist (ERA) marketed in the European Union (EU) and some other countries by GlaxoSmithKline (GSK) and in the United States as LETAIRIS® by Gilead Sciences Inc. Ambrisentan is indicated for the treatment of adult patients with PAH to improve exercise capacity, decrease the symptoms of PAH, and delay clinical worsening. The primary purpose of this paediatric study is to provide clinically relevant information on the safety and pharmacokinetic profile of ambrisentan in children with the most common causes of PAH in this age group. The design of the study is also intended to provide information to guide dose selection and supportive efficacy data in this age group. Despite the fact that none of the currently available adult treatments are licensed for use in children \<12 yrs, (with the exception of bosentan which was recently approved for use in paediatric population from 2 years of age) they are widely used off label. This study will provide useful prescribing information to the medical community for treating this orphan disease in children in this environment of rapidly changing medical practice. This study is part of a Paediatric Investigational Plan (PIP; EMEA-000434-PIP01-08) agreed with the European Medicines Agency's Paediatric Committee (PDCO).