ConclusionThis RCT showed that a new non-viral-based gene therapy for cystic fibrosis was able to produce “modest” benefits in lung function compared to a placebo. The treatments were given once a month for a year. The study had many strengths, including its double-blind randomised design, recruiting adequate numbers to demonstrate real differences between groups, and using pre-specified outcomes and sub-analysis. This means we can be confident in the reliability of the findings presented. Although the findings of this study are encouraging, there are always limitations. These include: This study was relatively small, recruiting just 140 patients. This is normal for a phase II trial, but large clinical trials are needed to fully assess the effects and safety of this treatment in devel...