Duncan M. Geddes

Two-, six-, and 12-minute walking tests in respiratory disease.

Over the ensuing seven months she had three more clinical relapses, each accompanied by reappearance in the stools of either the organism or its cytotoxin, or both. Each improvement after vancomycin (eight to 14-daycourses) was accompanied by disappearance of the organism. At one point she was given cholestyramine, but she was unable to tolerate it. Her illness was punctuated by malnutrition and episodes of heart failure. She was given no other antibiotics. After the sixth relapse maintenance treatment with oral vancomycin 125 mg eight-hourly was begun. With this regimen diarrhoea was controlled and stools over the next 10 weeks remained negative for C difficile and its cytotoxin. There was no adverse reaction to vancomycin throughout.

Liposome-mediated CFTR gene transfer to the nasal epithelium of patients with cystic fibrosis

We report the results of a double-blind, placebo-controlled trial in nine cystic fibrosis (CF) subjects receiving cationic liposome complexed with a complementary DNA encoding the CF transmembrane conductance regulator (CFTR), and six CF subjects receiving only liposome to the nasal epithelium. No adverse clinical effects were seen and nasal biopsies showed no histological or immuno-histological changes. A partial restoration of the deficit between CF and non-CF subjects of 20% was seen for the response to low Cl− perfusion following CFTR cDNA administration. This was maximal around day three and had reverted to pretreatment values by day seven. In some cases the response to low Cl− was within the range for non-CF subjects. Plasmid DNA and transgene-derived RNA were detected in the majority of treated subjects. Although these data are encouraging, it is likely that transfection efficiency and the duration of expression will need to be increased for therapeutic benefit.

Cationic lipid-mediated CFTR gene transfer to the lungs and nose of patients with cystic fibrosis: a double-blind placebo-controlled trial

BACKGROUND We and others have previously reported significant changes in chloride transport after cationic-lipid-mediated transfer of the cystic fibrosis transmembrane conductance regulator (CFTR) gene to the nasal epithelium of patients with cystic fibrosis. We studied the safety and efficacy of this gene transfer to the lungs and nose of patients with cystic fibrosis in a double-blind placebo-controlled trial. METHODS Eight patients with cystic fibrosis were randomly assigned DNA-lipid complex (active) by nebulisation into the lungs followed 1 week later by administration to the nose. Eight control patients followed the same protocol but with the lipid alone (placebo). Safety was assessed clinically, by radiography, by pulmonary function, by induced sputum, and by histological analysis. Efficacy was assessed by analysis of vector-specific CFTR DNA and mRNA, in-vivo potential difference, epifluorescence assay of chloride efflux, and bacterial adherence. FINDINGS Seven of the eight patients receiving the active complex reported mild influenza-like symptoms that resolved within 36 h. Six of eight patients in both the active and placebo groups reported mild airway symptoms over a period of 12 h following pulmonary administration. No specific treatment was required for either event. Pulmonary administration resulted in a significant (p<0.05) degree of correction of the chloride abnormality in the patients receiving active treatment but not in those on placebo when assessed by in-vivo potential difference and chloride efflux. Bacterial adherence was also reduced. We detected no alterations in the sodium transport abnormality. A similar pattern occurred following nasal administration. INTERPRETATION Cationic-lipid-mediated CFTR gene transfer can significantly influence the underlying chloride defect in the lungs of patients with cystic fibrosis.

Effect of Lung-Volume–Reduction Surgery in Patients with Severe Emphysema

BACKGROUND Although many patients with severe emphysema have undergone lung-volume-reduction surgery, the benefits are uncertain. We conducted a randomized, controlled trial of the surgery in patients with emphysema. Patients with isolated bullae were excluded because such patients are known to improve after bullectomy. METHODS Potentially eligible patients were given intensive medical treatment and completed a smoking-cessation program and a six-week outpatient rehabilitation program before random assignment to surgery or continued medical treatment. After 15 patients had been randomized, the entry criteria were modified to exclude patients with a carbon monoxide gas-transfer value less than 30 percent of the predicted value or a shuttle-walking distance of less than 150 m, because of the deaths of 5 such patients (3 treated surgically and 2 treated medically). RESULTS Of the 174 subjects who were initially assessed, 24 were randomly assigned to continued medical treatment and 24 to surgery. At base line in both groups, the median forced expiratory volume in one second (FEV1) was 0.75 liter, and the median shuttle-walking distance was 215 m. Five patients in the surgical group (21 percent) and three patients in the medical group (12 percent) died (P=0.43). After six months, the median FEV1 had increased by 70 ml in the surgical group and decreased by 80 ml in the medical group (P=0.02). The median shuttle-walking distance increased by 50 m in the surgical group and decreased by 20 m in the medical group (P=0.02). There were similar changes on a quality-of-life scale and similar changes at 12 months of follow-up. Five of the 19 surviving patients in the surgical group had no benefit from the treatment. CONCLUSIONS In selected patients with severe emphysema, lung-volume-reduction surgery can improve FEV1, walking distance, and quality of life. Whether it reduces mortality is uncertain.

Bronchoscopic volume reduction with valve implants in patients with severe emphysema.

Eight patients with severe emphysema entered a pilot study of unilateral volume reduction by endobronchial valve insertion. Five patients had emphysema judged too severe for volume reduction surgery and three refused the operation. After valve insertions, the median forced expiratory volume in 1 s (FEV1) increased from 0.79 L (range 0.61-1.07) to 1.06 L (0.75-1.22) (difference 34%, p=0.028) and the median diffusing capacity (TL(CO)) increased from 3.05 mL/min/mm Hg (2.35-4.71) to 3.92 mL/min/mm Hg (2.89-5.40) (difference 29%, p=0.017). CT scans showed a substantial reduction in regional volume in four of the eight patients. Two patients developed a transient pneumothorax (one requiring drainage) but we recorded no other important adverse effects during follow-up. Lung-volume reduction can be achieved with unilateral bronchoscopically placed valve implants in patients with severe emphysema with acceptable short-term safety and worthwhile functional benefits.

Efficient gene transfer to airway epithelium using recombinant Sendai virus

Clinical studies of gene therapy for cystic fibrosis (CF) suggest that the key problem is the efficiency of gene transfer to the airway epithelium. The availability of relevant vector receptors, the transient contact time between vector and epithelium, and the barrier function of airway mucus contribute significantly to this problem. We have recently developed recombinant Sendai virus (SeV) as a new gene transfer agent. Here we show that SeV produces efficient transfection throughout the respiratory tract of both mice and ferrets in vivo, as well as in freshly obtained human nasal epithelial cells in vitro. Gene transfer efficiency was several log orders greater than with cationic liposomes or adenovirus. Even very brief contact time was sufficient to produce this effect, and levels of expression were not significantly reduced by airway mucus. Our investigations suggest that SeV may provide a useful new vector for airway gene transfer.

Effects of dihydrocodeine, alcohol, and caffeine on breathlessness and exercise tolerance in patients with chronic obstructive lung disease and normal blood gases.

We measured breathlessness and exercise tolerance in 12 patients with chronic airways obstruction, moderate or severe breathlessness, and low or normal arterial carbon dioxide tension, after the patients received dihydrocodeine, alcohol, caffeine, or placebo (through double-blind administration). Forty-five minutes after ingestion, dihydrocodeine had reduced breathlessness by 20 per cent and increased exercise tolerance by 18 per cent, with a reduction in ventilation and oxygen consumption at submaximal work loads but with no change in spirometric volumes. Oxygen also reduced breathlessness and provided additional benefit to that achieved with dihydrocodeine (at three hours after ingestion) when the two were given together: the reduction of breathlessness was 18 per cent with dihydrocodeine; 22 per cent with oxygen; and 32 per cent with dihydrocodeine plus oxygen. Alcohol increased forced vital capacity by 9 per cent, and exercise tolerance by 7 per cent. Caffeine had no deleterious effect on breathlessness or exercise tolerance, despite increasing ventilation during rest and exercise. We conclude that opiates may be valuable for the treatment of breathlessness in selected patients; further evaluation is needed, particularly of the long-term benefits and safety.

Gene Therapy Progress and Prospects: Cystic fibrosis

Our first review on progress and prospects in cystic fibrosis (CF) gene therapy was published in this series in October 2002. We now summarize the progress made since then and comment on the prospects for CF gene therapy over the next couple of years. Three clinical trials have been carried out, further supporting the proof-of-principle that gene transfer to the airway epithelium is feasible. Developments in viral and non-viral vectors, as well as recent alternative strategies such as gene repair, trans-splicing and stem cell therapy will be reviewed.

Efficacy and safety of short-term administration of aerosolised recombinant human DNase I in adults with stable stage cystic fibrosis

Chronic pulmonary infection is the major cause of morbidity and mortality in cystic fibrosis. High levels of DNA in the sputum make the sputum viscous and difficult to expectorate. Recombinant human deoxyribonuclease (rhDNase) in vitro has been shown to reduce the viscoelasticity of the sputum from CF patients. We have done a phase II double-blind randomised placebo-controlled trial in which patients received either 2.5 mg rhDNase twice daily or placebo for 10 days. All patients had forced vital capacity (FVC) above 40% predicted and were clinically stable. Patients were followed up for 42 days from the start of drug/placebo administration. All 71 randomised patients, aged 16-55, completed every aspect of the study and baseline characteristics were similar in the two groups. Baseline forced expiratory volume in one second (FEV1) was 46% of predicted for patients randomised to rhDNase, and 48% for those randomised to placebo; and baseline FVC was 76% of predicted for both groups. The mean percentage change in FEV1 from baseline was a 13.3% rise on rhDNase and a 0.2% fall on placebo (p < 0.001). FVC rose 7.2% in the rhDNase group and 2.3% in the placebo group (not significant). There were no life-threatening adverse events and no anaphylactic reactions. There was no significant difference in side-effects between the groups. This study confirms that short-term administration of rhDNase in stable patients with cystic fibrosis is safe and improves lung function.

Barriers to and new approaches for gene therapy and gene delivery in cystic fibrosis

Abstract Clinical trials of gene therapy for cystic fibrosis suggest that current levels of gene transfer efficiency are probably too low to result in clinical benefit, largely as a result of the barriers faced by gene transfer vectors within the airways. The respiratory epithelium has evolved a complex series of extracellular barriers (mucus, lack of receptors, immune surveillance, etc.) aimed at preventing penetration of lumenally delivered materials, including gene therapy vectors. In addition, once in the cell, further hurdles have to be overcome, including DNA degradation, nuclear import and the ability to maintain long-term transgene expression. Strategies to overcome these barriers will be addressed in this review and include the use of: (i) clinically relevant adjuncts to overcome the extra- and intracellular barriers; (ii) less-conventional delivery routes, such as intravenous or in utero administration; (iii) more efficient non-viral vectors and ‘stealth’ viruses which can be re-administered; and (iv) new approaches to prolong transgene expression by means of alternative promoters or integrating vectors. These advances have the potential to improve the efficiency of gene delivery to the airway epithelium, thus making gene therapy a more realistic option for cystic fibrosis.