PTC Therapeutics announced that it has completed patient enrollment in its second Phase 3 clinical trial, known as ACT CF, to evaluate Translarna™ (ataluren) as treatment for patients with nonsense mutation cystic fibrosis (nmCF).

Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR). Nonsense mutations are categorized as Class I mutations that result in limited production, or a lack of production, of the CFTR protein. CF patients with Class I mutations usually experience more severe disease progression compared to those with the other CF genotypes, resulting in a higher probability of end-stage lung disease and a higher prevalence of pancreatic insufficiency. Around 10% of patients have CF due to a Class I nonsense mutation in at least one allele of the CFTR gene.

Translarna is a protein restoration therapy designed to enable the formation of a functioning protein in patients with genetic disorders caused by a nonsense mutation.

“We are very pleased by the enthusiastic response from our clinical investigators and strong interest from patients to participate in our ACT CF study,” said Stuart Peltz, PhD, Chief Executive Officer of PTC Therapeutics, in a recent press release. “Based on the results from our previous Phase 3 study, we believe that Translarna has the potential to meaningfully improve lung function and decrease pulmonary exacerbations in nonsense mutation cystic fibrosis patients by targeting the underlying cause of the disease.”

In September 2015, the European Medicines Agency (EMA) confirmed the submission of a variation for a new clinical indication for Translarna for the treatment of nmCF. The therapy was given marketing authorization in Europe in August 2014 for the treatment of nonsense mutation Duchenne muscular dystrophy (nmDMD) in patients age 5 and older.

The company’s regulatory application for Translarna in nmCF was based on the results of a previously completed Phase 3 double-blind, placebo-controlled clinical trial that compared Translarna to placebo in patients with nmCF.