Lancet Respir Med. 2015 Sep;3(9):684-91. doi: 10.1016/S2213-2600(15)00245-3. Epub 2015 Jul 3.

Randomised, double-blind, placebo-controlled, phase 2b trial

Two cystic fibrosis centres; patients recruited from 18 sites in the UK. Patients (aged >/=12 years) with a forced expiratory volume in 1 s (FEV1) of 50-90% predicted and any combination of CFTR mutations

Patients were randomly assigned to receive 5 mL of either nebulised pGM169/GL67A gene-liposome complex or 0.9% saline (placebo) every 28 days (plus or minus 5 days) for 1 year. Randomisation was stratified by % predicted FEV1 (<70 vs >/=70%), age (<18 vs >/=18 years), inclusion in the mechanistic substudy, and dosing site (London or Edinburgh).

The primary endpoint was the relative change in % predicted FEV1. The primary analysis was per protocol.

Between June 12, 2012, and June 24, 2013, we randomly assigned 140 patients to receive placebo (n=62) or pGM169/GL67A (n=78), of whom 116 (83%) patients comprised the per-protocol population. We noted a significant, albeit modest, treatment effect in the pGM169/GL67A group versus placebo at 12 months' follow-up (3.7%, 95% CI 0.1-7.3; p=0.046). This outcome was associated with a stabilisation of lung function in the pGM169/GL67A group compared with a decline in the placebo group. We recorded no significant difference in treatment-attributable adverse events between groups.

Monthly application of the pGM169/GL67A gene therapy formulation was associated with a significant, albeit modest, benefit in FEV1 compared with placebo at 1 year, indicating a stabilisation of lung function in the treatment group. Further improvements in efficacy and consistency of response to the current formulation are needed before gene therapy is suitable for clinical care; however, our findings should also encourage the rapid introduction of more potent gene transfer vectors into early phase trials.