Preparation for a first-in-man lentivirus trial in patients with cystic fibrosis.

We have recently shown that non-viral gene therapy can stabilise the decline of lung function in patients with cystic fibrosis (CF). However, the effect was modest, and more potent gene transfer agents are still required. Fuson protein (F)/Hemagglutinin/Neuraminidase protein (HN)-pseudotyped lentiviral vectors are more efficient for lung gene transfer than non-viral vectors in preclinical models. In preparation for a first-in-man CF trial using the lentiviral vector, we have undertaken key translational preclinical studies. Regulatory-compliant vectors carrying a range of promoter/enhancer elements were assessed in mice and human air-liquid interface (ALI) cultures to select the lead candidate; cystic fibrosis transmembrane conductance receptor (CFTR) expression and function were assessed in CF models using this lead candidate vector. Toxicity was assessed and 'benchmarked' against the leading non-viral formulation recently used in a Phase IIb clinical trial. Integration site profiles were mapped and transduction efficiency determined to inform clinical trial dose-ranging. The impact of pre-existing and acquired immunity against the vector and vector stability in several clinically relevant delivery devices was assessed. A hybrid promoter hybrid cytosine guanine dinucleotide (CpG)- free CMV enhancer/elongation factor 1 alpha promoter (hCEF) consisting of the elongation factor 1α promoter and the cytomegalovirus enhancer was most efficacious in both murine lungs and human ALI cultures (both at least 2-log orders above background). The efficacy (at least 14% of airway cells transduced), toxicity and integration site profile supports further progression towards clinical trial and pre-existing and acquired immune responses do not interfere with vector efficacy. The lead rSIV.F/HN candidate expresses functional CFTR and the vector retains 90-100% transduction efficiency in clinically relevant delivery devices. The data support the progression of the F/HN-pseudotyped lentiviral vector into a first-in-man CF trial in 2017.

Differential global gene expression in cystic fibrosis nasal and bronchial epithelium.

Respiratory epithelium is the target of therapies, such as gene therapy, for cystic fibrosis (CF) lung disease. To determine the usefulness of the nasal epithelium as a pre-screen for lung-directed therapies, we profiled gene expression in CF and non-CF nasal and bronchial epithelium samples using Illumina HumanRef-8 Expression BeadChips. 863 genes were differentially expressed between CF and non-CF bronchial epithelium but only 15 were differentially expressed between CF and non-CF nasal epithelium (≥1.5-fold, P≤0.05). The most enriched pathway in CF bronchial epithelium was inflammatory response, whereas in CF nasal epithelium it was amino acid metabolism. We also compared nasal and bronchial epithelium in each group and identified differential expression of cellular movement genes in CF patients and cellular growth genes in non-CF subjects. We conclude that CF and non-CF nasal and bronchial epithelium are transcriptionally distinct and CF nasal epithelium is not a good surrogate for the lung respiratory epithelium.

Role of biophysical parameters on ex vivo and in vivo gene transfer to the airway epithelium by polyethylenimine/albumin complexes.

Efficient gene transfer to the airways by nonviral vectors is a function of different parameters, among which the size and the charge of the transfecting particles. The aim of this study was to determine the transfection efficiency of polyethylenimine (PEI)/albumin polyplexes in ex vivo and in vivo models of respiratory epithelium and to correlate it with biophysical characteristics of the particles. Complexes were obtained by adding different amounts of human serum albumin (HSA) to PEI polyplexes preformed in saline. The presence of HSA caused the formation of bigger and more negative polyplexes and increased PEI transfection efficiency in primary respiratory epithelial cells by 4-6-fold. For in vivo administration to the lung, PEI polyplexes were formed in water and optimized with respect to the N/ P ratio. PEI/pC-Luc complexes gave the highest luciferase expression at N/ P 15 when administered through the trachea. At this N/ P ratio, the size and the surface charge of albumin-containing polyplexes were not different as compared with plain PEI polyplexes. Formulation of PEI polyplexes in the presence of HSA or murine serum albumin (MSA) resulted in a 2-fold increase in luciferase expression. In mice treated with PEI or PEI/MSA polyplexes containing the nuclear beta-gal gene, X-gal staining revealed that transfected cells localized at the bronchiolar epithelium and that PEI/MSA transfected four times as many cells as PEI ( p < 0.05). Finally, double administration of PEI/MSA polyplexes resulted in a further enhancement of transfection of the lung. Our data show that serum albumin enhances PEI-mediated gene transfer to airway epithelial cells in vivo, likely facilitating the uptake of polyplexes, and indicate that this formulation would fulfill the requirement of repeated administration, as necessary in chronic lung diseases like cystic fibrosis.

Repeated nebulisation of non-viral CFTR gene therapy in patients with cystic fibrosis: a randomised, double-blind, placebo-controlled, phase 2b trial.

BACKGROUND: Lung delivery of plasmid DNA encoding the CFTR gene complexed with a cationic liposome is a potential treatment option for patients with cystic fibrosis. We aimed to assess the efficacy of non-viral CFTR gene therapy in patients with cystic fibrosis. METHODS: We did this randomised, double-blind, placebo-controlled, phase 2b trial in two cystic fibrosis centres with 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, were randomly assigned, via a computer-based randomisation system, 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). Participants and investigators were masked to treatment allocation. The primary endpoint was the relative change in % predicted FEV1. The primary analysis was per protocol. This trial is registered with ClinicalTrials.gov, number NCT01621867. FINDINGS: 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. INTERPRETATION: 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. FUNDING: Medical Research Council/National Institute for Health Research Efficacy and Mechanism Evaluation Programme.

HIV-1 Tat protein transduction domain peptide facilitates gene transfer in combination with cationic liposomes.

The protein transduction domain (PTD) of the HIV-1 Tat protein can facilitate the cellular and nuclear uptake of macromolecular particles. Here, we demonstrate that incorporation without covalent linkage of a 17-amino acid PTD peptide into gene delivery lipoplexes improves gene transfer. Tat/Liposome/DNA (TLD) transfection, as evaluated by Fluorescence Activated Cell Scan analysis of a Green Fluorescence Protein expression plasmid, enabled transfection of highly recalcitrant primary cells in the form of air/liquid interface cultures of sheep tracheal epithelium. Treatment with chloroquine increased, and incubation at low temperature decreased, TLD transfection, suggesting that the endocytosis uptake pathway is involved.

Potent stimulation of gene expression by histone deacetylase inhibitors on transiently transfected DNA.

Transcription activity of chromatin is associated with histone acetylation which is regulated by recruitment of histone acetyltransferases and deacetylases (HDAC) to specific chromatin regions. We have tested how expression of a transfected or stably introduced gene correlates with histone acetylation. Our results demonstrate that expression of transiently transfected green fluorescence protein (GFP) genes is significantly enhanced by HDAC inhibitors. Although HDAC treatment did not induce noticeable changes in the chromatin structure of genomic DNA, chromatin immunoprecipitation showed that more transiently transfected DNA is assembled into chromatin containing acetylated histones in HDAC inhibitor treated cells when compared to untreated cells. For stably integrated GFP, the expression response to HDAC inhibitors varies between independent stable cell lines. However, there was no difference in histone acetylation associated with the integrated transgene between HDAC inhibitor responsive and non-responsive cells. Furthermore, the overall enhancement of transgene expression by HDAC inhibitors was not as pronounced as in transiently transfected cells.