A randomised, double-blind, placebo-controlled trial of repeated nebulisation of non-viral cystic fibrosis transmembrane conductance regulator (CFTR) gene therapy in patients with cystic fibrosis.

Alton EW, Armstrong DK, Ashby D, Bayfield KJ, Bilton D, Bloomfield EV, Boyd AC, Brand J, Buchan R, Calcedo R, Carvelli P, Chan M, Cheng SH, Collie DS, Cunningham S, Davidson HE, Davies G, Davies JC, Davies LA, Dewar MH, Doherty A, Donovan J, Dwyer NS, Elgmati HI, Featherstone RF, Gavino J, Gea-Sorli S, Geddes DM, Gibson JSR, Gill DR, Greening AP, Griesenbach U, Hansell DM, Harman K, Higgins TE, Hodges SL, Hyde SC, Hyndman L, Innes JA, Jacob J, Jones N, Keogh BF, Limberis MP, Lloyd-Evans P, Maclean AW, Manvell MC, McCormick D, McGovern M, McLachlan G, Meng C, Montero MA, Milligan H, Moyce LJ, Murray GD, Nicholson AG, Osadolor T, Parra-Leiton J, Porteous DJ, Pringle IA, Punch EK, Pytel KM, Quittner AL, Rivellini G, Saunders CJ, Scheule RK, Sheard S, Simmonds NJ, Smith K, Smith SN, Soussi N, Soussi S, Spearing EJ, Stevenson BJ, Sumner-Jones SG, Turkkila M, Ureta RP, Waller MD, Wasowicz MY, Wilson JM, Wolstenholme-Hogg P

Efficacy and Mechanism Evaluation

Efficacy and Mechanism Evaluation (2016) Volume: 3 Issue: 5

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Background

Cystic fibrosis (CF) is a chronic, life-limiting disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene leading to abnormal airway surface ion transport, chronic lung infections, inflammation and eventual respiratory failure. With the exception of the small-molecule potentiator, ivacaftor (Kalydeco®, Vertex Pharmaceuticals, Boston, MA, USA), which is suitable for a small proportion of patients, there are no licensed therapies targeting the basic defect. The UK Cystic Fibrosis Gene Therapy Consortium has taken a cationic lipid-mediated CFTR gene therapy formulation through preclinical and clinical development.

Objective

To determine clinical efficacy of the formulation delivered to the airways over a period of 1 year in patients with CF.

Design

This was a randomised, double-blind, placebo-controlled Phase IIb trial of the CFTR gene–liposome complex pGM169/GL67A. Randomisation was performed via InForm™ version 4.6 (Phase Forward Incorporated, Oracle, CA, USA) and was 1 : 1, except for patients in the mechanistic subgroups (2 : 1). Allocation was blinded by masking nebuliser chambers.

Settings

Data were collected in the clinical and scientific sites and entered onto a trial-specific InForm, version 4.6 database.

Participants

Patients with CF aged ≥ 12 years with forced expiratory volume in the first second (FEV1) between 50% and 90% predicted and any combination of CFTR mutations. The per-protocol group (≥ 9 doses) consisted of 54 patients receiving placebo (62 randomised) and 62 patients receiving gene therapy (78 randomised).

Interventions

Subjects received 5 ml of nebulised pGM169/G67A (active) or 0.9% saline (placebo) at 28 (±5)-day intervals over 1 year.

Main outcome measures

The primary end point was the relative change in percentage predicted FEV1 over the 12-month period. A number of secondary clinical outcomes were assessed alongside safety measures: other spirometric values; lung clearance index (LCI) assessed by multibreath washout; structural disease on computed tomography (CT) scan; the Cystic Fibrosis Questionnaire – Revised (CFQ-R), a validated quality-of-life questionnaire; exercise capacity and monitoring; systemic and sputum inflammatory markers; and adverse events (AEs). A mechanistic study was performed in a subgroup in whom transgene deoxyribonucleic acid (DNA) and messenger ribonucleic acid (mRNA) was measured alongside nasal and lower airway potential difference.

Results

There was a significant (p = 0.046) treatment effect (TE) of 3.7% [95% confidence interval (CI) 0.1% to 7.3%] in the primary end point at 12 months and in secondary end points, including forced vital capacity (FVC) (p = 0.031) and CT gas trapping (p = 0.048). Other outcomes, although not reaching statistical significance, favoured active treatment. Effects were noted by 1 month and were irrespective of sex, age or CFTR mutation class. Subjects with a more severe baseline FEV1 had a FEV1 TE of 6.4% (95% CI 0.8% to 12.1%) and greater changes in many other secondary outcomes. However, the more mildly affected group also demonstrated benefits, particularly in small airway disease markers such as LCI. The active group showed a significantly (p = 0.032) greater bronchial chloride secretory response. No difference in treatment-attributable AEs was seen between the placebo and active groups.

Conclusions

Monthly application of the pGM169/GL67A gene therapy formulation was associated with an improvement in lung function, other clinically relevant parameters and bronchial CFTR function, compared with placebo.

Limitations

Although encouraging, the improvement in FEV1 was modest and was not accompanied by detectable improvement in patients’ quality of life.

Future work

Future work will focus on attempts to increase efficacy by increasing dose or frequency, the coadministration of a CFTR potentiator, or the use of modified viral vectors capable of repeated administration.

Trial registration

ClinicalTrials.gov NCT01621867.

Funding

This project was funded by the Efficacy and Mechanism Evaluation (EME) programme, a Medical Research Council and National Institute for Health Research partnership.

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