Patients with cystic fibrosis (CF) who received ivacaftor, a transmembrane conductance regulator (CFTR) modulator, had significantly lower risks for death, transplantation, hospitalization, and pulmonary exacerbation than untreated comparators, according to the results of an observational, post-approval safety study published in Thorax.

Ivacaftor targets the fundamental defect in CF and is the first in a new class of drugs, the CFTR potentiators. However, because CF is a chronic illness, ivacaftor is intended for lifelong use, and determining the long-term effects of therapy, including both efficacy and safety, is crucial.

Leona Bessonova, PhD, of Vertex Pharmaceuticals, Inc., in Boston, Massachusetts, and colleagues, analyzed data from 1667 patients treated with ivacaftor and 8269 untreated matched comparator patients drawn from both US and UK CF registries for risks for death, transplantation, hospitalization, pulmonary exacerbation, CF-related complications and microorganisms, and changes in lung function. Patients were treated for an average of 2 years in the United States and 1.3 years in the United Kingdom.

Of the US patients, the risk for death was significantly lower in the ivacaftor group than the comparator group (0.6% vs 1.6%; P =.0110), as was the risk for transplantation (0.2% vs 1.1%; P =.0017). Likewise, the risks for hospitalization (27.5% vs 43.1%; P <.0001) and pulmonary exacerbation (27.8% vs 43.3%; P <.0001) were significantly lower for ivacaftor than for the comparator. Similar observations were found in the UK patients.

In both registries, the risk for CF-related complications and the prevalence of select microorganisms was lower and patients had better preserved lung function with ivacaftor therapy. The investigators noted that several important pathogens, including Staphylococcus aureus, Pseudomonas aeruginosa, and Aspergillus spp were less prevalent in the ivacaftor group. 

As with any observational study, this study was limited by the potential for confounding factors. The lack of scheduled visits, standardized assessments, and exact dates of therapy initiation were among the other limitations. Nonetheless, this study represents the largest analysis of patients treated with ivacaftor to date, and these findings add support to the case for CF disease modification by CFTR modulation.

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Disclosures: Funding for this study was provided by Vertex Pharmaceuticals Incorporated.

Reference

Bessonova L, Volkova N, Higgins M, et al. Data from the US and UK cystic fibrosis registries support disease modification by CFTR modulation with ivacaftor [published online May 10, 2018]. Thorax. doi:10.1136/thoraxjnl-2017-210394