Cystic Fibrosis: Gene Therapy

Abstract

Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations of the CFTR gene, which encodes a member of the adenosine triphosphate‐binding cassette superfamily of transmembrane proteins. CFTR normally acts as a cyclic adenosine monophosphate‐activated chloride channel and as a regulator of other ion channels. The main cause of morbidity and mortality is the effect of CFTR dysfunction on the lung, which reduces life expectancy of CF patients (current median approximately 40 years according to UK and US national patient registries). There has been some progress in the identification of pharmacological agents that can correct the CFTR defect in patients carrying some classes of mutation, but with nearly 2000 different disease‐causing mutations reported, gene therapy remains the most likely option for the amelioration of lung disease in the majority of CF sufferers. The progress achieved and the hurdles identified as a result of the clinical trials of gene therapy vectors in CF patients are reviewed.

Key Concepts:

  • CF is a monogenic recessive disease with an incidence of 1:2500 in populations of Caucasian descent in particular, caused by mutations in the CFTR gene.

  • It is a life‐limiting condition and disease management involves a heavy therapeutic burden with no definitive cure.

  • Disruption of the CFTR gene leads to incorrect or insufficient transport of chloride ions across the epithelial cells of the body with a range of consequences in different organs, crucially inadequate clearance of bacteria from the lungs due to ineffective mucociliary clearance, resulting in progressive fibrosis and clogging of the lung with mucus, and eventually respiratory failure.

  • Discovery of the genetic basis for CF quickly led to evaluation of gene therapy as a therapeutic option, with a range of viral and nonviral vectors.

  • Although the vectors tested showed some efficacy in terms of correcting the fundamental chloride transport defect, no CF gene therapy trial has so far been able to demonstrate long‐term clinical improvement.

Keywords: gene therapy; clinical trials; lung; cystic fibrosis; nonviral; gene transfer agent; viral vectors

Figure 1.

Schematic representation of CFTR biosynthesis, CF‐causing mutations and pharmacological interventions under investigation. Biosynthesis of CFTR, shown on left‐hand side, involves translation of the spliced mRNA in the endoplasmic reticulum (ER) with concomitant chaperone‐dependent folding, export through the Golgi for post‐translational maturation (complex glycosylation), and transport to the membrane in clathrin‐coated vesicles for insertion into the apical membrane. There, CFTR channel opening is regulated by ATP hydrolysis at NBD1 and 2, as well as phosphorylation of the R domain, and eventually CFTR is either recycled or degraded via the lysosomal and/or ubiquitin‐dependent degradation pathways (Rogan et al., ). The apical and basolateral surfaces are separated by the tight junctions indicated in orange. Channels that also contribute to the balance of salt and water across the apical membrane include calcium‐activated chloride channel (CaCC) and epithelial sodium channel (ENaC). The middle section outlines how CF‐causing mutations can affect the different steps in CFTR biosynthesis. The most common CF allele, F508del, produces a class II mutant with increased degradation of the misfolded protein in the ER or the Golgi (other examples include N1303K, G85E); class I mutations (∼10% of all CF mutations) typically involve early termination of transcription especially due to premature stop codons (e.g. G542X, W1282X); class III and class IV mutants encode correctly folded and apically‐localised CFTR that, respectively, has gating defects or is aberrantly regulated (∼2–3% of all CF mutations, e.g. G551D, R560T) and conductance defects (<2% of all CF mutations, e.g. R117H, R347P); class V mutants typically affect the rate of synthesis of CFTR protein that is otherwise normal, leading to a reduction in chloride transport (<1% of all CF mutations, e.g. 2849+10kbC→T; 2789+5G→A) (O'Sullivan and Freedman, ; Rogan et al., ; Pettit, ). The right‐hand panel shows the types of drug molecules under investigation, which may be able to improve ion balance across the respiratory epithelium, by improving expression, translation, maturation, and channel properties of the various CFTR mutants, or interfere with excessive sodium transport from the airway surface through ENaC (Ong and Ramsey, ; Rowe and Verkman, ).

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References

Aitken ML, Moss RB, Waltz DA et al. (2001) A Phase I study of aerosolized administration of tgAAVCF to cystic fibrosis subjects with mild lung disease. Human Gene Therapy 12(15): 1907–1916.

Alton EW, Boyd AC, Cheng SH et al. (2013) A randomised, double‐blind, placebo‐controlled phase IIB clinical trial of repeated application of gene therapy in patients with cystic fibrosis. Thorax 68(11): 1075–1077.

Alton EW, Stern M, Farley R et al. (1999) Cationic lipid‐mediated CFTR gene transfer to the lungs and nose of patients with cystic fibrosis: a double‐blind placebo‐controlled trial. Lancet 353(9157): 947–954.

Bellon G, Michel‐Calemard L, Thouvenot D et al. (1997) Aerosol administration of a recombinant adenovirus expressing CFTR to cystic fibrosis patients: a phase I clinical trial. Human Gene Therapy 8(1): 15–25.

Cao H, Machuca TN, Yeung JC et al. (2013) Efficient gene delivery to pig airway epithelia and submucosal glands using helper‐dependent adenoviral vectors. Molecular Therapy – Nucleic Acids 2: e127.

Cao H, Yang T, Li X‐F et al. (2011) Readministration of helper‐dependent adenoviral vectors to mouse airway mediated via transient immunosuppression. Gene Therapy 18(2): 173–181.

Caplen NJ, Alton EW, Middleton PG et al. (1995) Liposome‐mediated CFTR gene transfer to the nasal epithlium of patients with cystic fibrosis. Nature Medicine 1(1): 39–46.

Chen X, Kube DM, Cooper MJ and Davies PB (2008) Cell surface nucleolin serves as receptor for DNA nanoparticles composed of PEGylated polylysine and DNA. Molecular Therapy 16(2): 333–342.

Crystal RG, McElvaney NG, Rosenfeld MA et al. (1994) Administration of an adenovirus containing the human CFTR cDNA to the respiratory tract of individuals with cystic fibrosis. Nature Genetics 8(1): 42–51.

Cystic Fibrosis Foundation Patient Registry (2013) 2012 Annual Data Report. Bethesda, MD: Cystic Fibrosis Foundation.

Davies JC, Davies G, Gill D et al. (2011) Safety and expression of a single dose of lipid‐mediated CFTR gene therapy to the upper and lower airways of patients with CF. Pediatric Pulmonology 46(suppl. 46): S34.

Excoffon KJDA, Koerber JT, Dickey DD et al. (2009) Directed evolution of adeno‐associated virus to an infectious respiratory virus. Proceedings of the National Academy of Sciences of the USA 106(10): 3865–3870.

Flotte TR, Afione SA, Solow R et al. (1993) Expression of the cystic fibrosis transmembrane conductance regulator from a novel adeno‐associated virus promoter. Journal of Biological Chemistry 268(5): 3781–3790.

Flotte TR, Zeitlin PL, Reynolds TC et al. (2003) Phase I trial of intranasal and endobronchial administration of a recombinant adeno‐associated virus serotype 2 (rAAV2)‐CFTR vector in adult cystic fibrosis patients: a two‐part clinical study. Human Gene Therapy 14(11): 1079–1088.

Gill DR, Southern KW, Mofford KA et al. (1997) A placebo‐controlled study of liposome‐mediated gene transfer to the nasal epithelium of patients with cystic fibrosis. Gene Therapy 4(3): 199–209.

Griesenbach U and Alton EWFW (2013) Expert opinion in biological therapy: update on developments in lung gene therapy. Expert Opinion on Biological Therapy 13(3): 345–360.

Griesenbach U, Inoue M, Meng C et al. (2012) Assessment of F/HN‐pseudotyped lentivirus as a clinically relevant vector for lung gene therapy. American Journal of Respiratory and Critical Care Medicine 186(9): 846–856.

Halbert CL, Standaert TA, Wilson CB and Miller AD (1998) Successful readministration of adeno‐associated virus vectors to the mouse lung requires transient immunosuppression during the initial exposure. Journal of Virology 72(12): 9795–9805.

Harvey BG, Leopold PL, Hackett NR et al. (1999) Airway epithelial CFTR mRNA expression in cystic fibrosis patients after repetitive administration of a recombinant adenovirus. Journal of Clinical Investigation 104(9): 1245–1255.

Hay JG, McElvaney NG, Herena J and Crystal RG (1995) Modification of nasal epithelial potential differences of individuals with cystic fibrosis consequent to local administration of a normal CFTR cDNA adenovirus gene transfer vector. Human Gene Therapy 6(11): 1487–1496.

Hemmi H, Takeuchi O, Kawai T et al. (2000) A Toll‐like receptor recognizes bacterial DNA. Nature 408(6813): 740–745.

Hyde SC, Pringle IA, Abdullah S et al. (2008) CpG‐free plasmids confer reduced inflammation and sustained pulmonary gene expression. Nature Biotechnology 26(5): 549–551.

Hyde SC, Southern KW, Gileadi U et al. (2000) Repeat administration of DNA/liposomes to the nasal epithelium of patients with cystic fibrosis. Gene Therapy 7(13): 1156–1165.

Joseph PM, O'Sullivan BP, Lapey A et al. (2001) Aerosol and lobar administration of a recombinant adenovirus to individuals with cystic fibrosis. I. Methods, safety, and clinical implications. Human Gene Therapy 12(11): 1369–1382.

Knowles MR, Hohneker KW, Zhou Z et al. (1995) A controlled study of adenoviral‐vector‐mediated gene transfer in the nasal epithelium of patients with cystic fibrosis. New England Journal of Medicine 333(13): 823–831.

Konstan MW, Davis PB, Wagener JS et al. (2004) Compacted DNA nanoparticles administered to the nasal mucosa of cystic fibrosis subjects are safe and demonstrate partial to complete cystic fibrosis transmembrane regulator reconstitution. Human Gene Therapy 15(12): 1255–1269.

Lee TWR and Southern KW (2013) Topical cystic fibrosis transmembrane conductance regulator gene replacement for cystif fibrosis‐related lung disease. Cochrane Database of Systematic Reviews 11: 1–39 (Art No.: CD005599).

Li C, Diprimio N, Bowles DE et al. (2012) Single amino acid modification of adeno‐associated virus capsid changes transduction and humoral immune profiles. Journal of Virology 86(15): 7752–7759.

Li X, Rossen N, Sinn PL et al. (2013) Integrin α6β4 identifies human distal lung epithelial progenitor cells with potential as a cell‐based therapy for cystic fibrosis lung disease. PLoS One 8(12): e83624.

Limberis MP, Vandenberghe LH, Zhang L, Pickles RJ and Wilson JM (2009) Transduction efficiencies of novel AAV vectors in mouse airway epithelium in vivo and human ciliated airway epithelium in vitro. Molecular Therapy 17(2): 294–301.

Moss RB, Milla C, Colombo J et al. (2007) Repeated aerosolized AAV‐CFTR for treatment of cystic fibrosis: a randomized placebo‐controlled phase 2B trial. Human Gene Therapy 18(8): 726–732.

Moss RB, Rodman D, Spencer LT et al. (2004) Repeated adeno‐associated virus serotype 2 aerosol‐mediated cystic fibrosis transmembrane regulator gene transfer to the lungs of patients with cystic fibrosis: a multicenter, double‐blind, placebo‐controlled trial. Chest 125(2): 509–521.

Noone PG, Hohneker KW, Zhou Z et al. (2000) Safety and biological efficacy of a lipid‐CFTR complex for gene transfer in the nasal epithelium of adult patients with cystic fibrosis. Molecular Therapy 1(1): 105–114.

Ong T and Ramsey BW (2013) Modifying disease in cystic fibrosis: current and future therapies on the horizon. Current Opinion in Pulmonary Medicine 19: 645–651.

O'Sullivan BP and Freedman SD (2009) Cystic fibrosis. The Lancet 373: 1891–1904.

Perricone MA, Morris JE, Pavelka K et al. (2001) Aerosol and lobar administration of a recombinant adenovirus to individuals with cystic fibrosis. II. Transfection efficiency in airway epithelium. Human Gene Therapy 12(11): 1383–1394.

Pettit RS (2012) Cystic fibrosis transmembrance conductance regulator‐modifying medications. Annals of Pharmacotherapy 46(7): 1065–1075.

Porteous DJ, Dorin JR, McLachlan G et al. (1997) Evidence for safety and efficacy of DOTAP cationic liposome mediated CFTR gene transfer to the nasal epithelium of patients with cystic fibrosis. Gene Therapy 4(3): 210–218.

Pringle IA, Hyde SC and Gill DR (2009) Non‐viral vectors in cystic fibrosis gene therapy: recent developments and future prospects. Expert Opinion on Biological Therapy 9(8): 991–1003.

Riordan JR, Rommens JM, Kerem BS et al. (1989) Identification of the cystic fibrosis gene: cloning and characterization of complementary DNA. Science 245(4922): 1066–1073; erratum Science 245(4925): 1437.

Rogan MP, Stoltz DA and Hornick DB (2011) Cystic fibrosis transmembrane conductance regulator intracellular processing, trafficking, and opportunities for mutation‐specific treatment. Chest 139(6): 1480–1490.

Rowe SM and Verkman AS (2013) Cystic fibrosis transmembrane regulator correctors and potentiators. Cold Spring Harbor Perspecitves in Medicine 3: a009761.

Ruiz FE, Clancy JP, Perricone MA et al. (2001) A clinical inflammatory syndrome attributable to aerosolized lipid‐DNA administration in cystic fibrosis. Human Gene Therapy 12(7): 751–761.

Sinn PL, Arias AC, Brogden KA and McCray PB Jr (2008) Lentivirus vector can be readministered to nasal epithelia without blocking immune responses. Journal of Virology 82(21): 10684–10692.

Stocker AG, Kremer KL, Koldej R et al. (2009) Single‐dose lentiviral gene transfer for lifetime airway gene expression. Journal of Gene Medicine 11(10): 861–867.

UK Cystic Fibrosis Registry (2013) Annual Data Report 2012: Summary. London, UK: Cystic Fibrosis Trust.

Wagner JA, Messner AH, Moran ML et al. (1999) Safety and biological efficacy of an adeno‐associated virus vector‐cystic fibrosis transmembrane regulator (AAV‐CFTR) in the cystic fibrosis maxillary sinus. Laryngoscope 109(2 Part 1): 266–274.

Wagner JA, Nepomuceno IB, Messner AH et al. (2002) A phase II, double‐blind, randomized, placebo‐controlled clinical trial of tgAAVCF using maxillary sinus delivery in patients with cystic fibrosis with antrostomies. Human Gene Therapy 13(11): 1349–1359.

Yan Z, Keiser NW, Song Y et al. (2013) A novel chimeric adenoassociated cirus 2/human Bocavirus 1 parvovirus vector efficiently transduces human airway epithelia. Molecular Therapy 21(12): 2181–2194.

Zabner J, Cheng SH, Meeker D et al. (1997) Comparison of DNA‐lipid complexes and DNA alone for gene transfer to cystic fibrosis airway epithelia in vivo. Journal of Clinical Investigation 100(6): 1529–1537.

Zabner J, Couture LA, Gregory RJ et al. (1993) Adenovirus‐mediated gene transfer transiently corrects the chloride transport defect in nasal epithelia of patients with cystic fibrosis. Cell 75(2): 207–216.

Zabner J, Ramsey BW, Meeker DP et al. (1996) Repeat administration of an adenovirus vector encoding cystic fibrosis transmembrane conductance regulator to the nasal epithelium of patients with cystic fibrosis. Journal of Clinical Investigation 97(6): 1504–1111.

Zhang LN, Karp P, Gerard CJ et al. (2004) Dual therapeutic utility of proteasome modulating agents for pharmaco‐gene therapy of the cystic fibrosis airway. Molecular Therapy 10(6): 990–1002.

Zielenski J (2000) Genotype and phenotype in cystic fibrosis. Respiration 67(2): 117–133.

Zuckerman JB, Robinson CB, McCoy KS et al. (1999) A phase I study of adenovirus‐mediated transfer of the human cystic fibrosis transmembrane conductance regulator gene to a lung segment of individuals with cystic fibrosis. Human Gene Therapy 10(18): 2973–2985.

Further Reading

Brunetti‐Pierri N and Ng P (2008) Progress and prospects: gene therapy for genetic diseases with helper‐dependent adenoviral vectors. Gene Therapy 15(8): 533–560.

Burney TJ and Davies JC (2012) Gene therapy for the treatment of cystic fibrosis. Application of Clinical Genetics 5: 29–36.

Griesenbach T and Alton EWFW (2013) Moving forward: cystic fibrosis gene therapy. Human Molecular Genetics 22: R52–R58.

Kwon I and Schaffer DV (2008) Designer gene delivery vectors: molecular engineering and evolution of adeno‐associated viral vectors for enhanced gene transfer. Pharmaceutical Research 25(3): 489–499.

Lobeck CC (2000) Cystic fibrosis. In: Scriver CR (ed.) The Metabolic and Molecular Bases of Inherited Disease, 8th edn, pp. 1605–1626. New York, NY: McGraw‐Hill.

Web Links

Cystic Fibrosis Mutation Database, Statistics (accessed on 10 Nov 2013). http://www.genet.sickkids.on.ca

Cystic Fibrosis Transmembrane Conductance Regulator, ATP‐Binding Cassette (Sub‐family C, Member 7) (CFTR); MIM: 602421. GeneLink. http://www.ncbi.nlm.nih.gov/gene/1080

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Sumner‐Jones, Stephanie G, and Gill, Deborah R(Apr 2014) Cystic Fibrosis: Gene Therapy. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0005749.pub2]