Chest
Volume 125, Issue 2, February 2004, Pages 509-521
Journal home page for Chest

Clinical Investigations
AEROSOLS
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

https://doi.org/10.1378/chest.125.2.509Get rights and content

Study objectives

The primary objective was to determine the safety and tolerability of repeated doses of aerosolized adeno-associated serotype 2 vector containing cystic fibrosis transmembrane conductance regulator (CFTR) complementary DNA (cDNA) [tgAAVCF], an adeno-associated virus (AAV) vector encoding the complete human CFTR cDNA. Secondary objectives included evaluation of pulmonary function assessed by spirometry, lung abnormalities by high-resolution CT (HRCT), airway cytokines, vector shedding, serum neutralizing antibody to AAV serotype 2 (AAV2), and gene transfer and expression in a subset of subjects undergoing bronchoscopy with bronchial brushings.

Design

Randomized, double-blind, placebo-controlled, phase II trial.

Setting

Eight cystic fibrosis (CF) centers in the United States.

Subjects

CF patients with mild lung disease, defined as FEV1 ≥ 60% predicted.

Interventions

Subjects were randomized to inhale three aerosolized doses of 1 × 1013 deoxyribonuclease-resistant particles of tgAAVCF or matching placebo at 30-day intervals using the Pari LC Plus nebulizer (PARI; Richmond, VA).

Measurements and results

Of 42 subjects randomized, 20 subjects received at least one dose of tgAAVCF and 17 subjects received placebo. No difference in the pattern of adverse events or laboratory abnormalities was noted between the two treatment groups. Improvements in induced-sputum interleukin-8 (p = 0.03) and FEV1 (p = 0.04) were observed at day 14 and day 30, respectively, in the group receiving tgAAVCF when compared to those receiving placebo. No significant differences in HRCT scans were noted. Vector shedding in sputum was observed at low levels up to 90 days after the third dose of vector. All subjects receiving tgAAVCF exhibited an increase (by at least fourfold) in serum AAV2-neutralizing antibodies and detectable levels in BAL fluid from five of six treated subjects undergoing BAL. Gene transfer but not gene expression was detected in a subset of six tgAAVCF subjects who underwent bronchoscopy.

Conclusions

Repeat doses of aerosolized tgAAVCF were safe and well tolerated, and resulted in encouraging trends in improvement in pulmonary function in patients with CF and mild lung disease.

Section snippets

Study Agent

Active study agent was tgAAVCF, a recombinant AAV2 vector genetically engineered to contain the complete coding region of the human CFTR cDNA. The vector was constructed by replacing the entire wild-type AAV viral coding sequence with the full-length human CFTR cDNA and a synthetic polyadenylation sequence based on murine β-globulin. This construct was flanked by the AAV2 inverted terminal repeat sequences that are required for viral replication and packaging during the manufacturing process.

Baseline Characteristics

Forty-six subjects underwent screening procedures between October 2000 and April 2002. Four subjects did not meet entry criteria because the baseline FEV1 was ≤ 60% of predicted. Forty-two subjects were randomized. After the first two subjects were randomized, the FDA imposed a 2-month hold in December 2000 on all clinical trials involving any AAV vector to review findings from an animal study of a vector unrelated to tgAAVCF.3031 The first subject, who had received one dose of study

Discussion

This study represents the first clinical evaluation of repeated aerosol dose delivery of CFTR DNA to the lower respiratory tract of patients with CF using an AAV vector. The study was designed with safety and tolerability as the primary end points. Thus, the trial was powered and sample size calculated to detect differences in adverse events between subjects receiving tgAAVCF and placebo. The reason for this emphasis on safety lies in clinical toxicity encountered in previous attempts to

References (39)

  • HA Berger et al.

    Identification and regulation of the cystic fibrosis transmembrane conductance regulator-generated chloride channel

    J Clin Invest

    (1991)
  • M Egan et al.

    Defective regulation of outwardly rectifying Cl- channels by protein kinase A corrected by insertion of CFTR

    Nature

    (1992)
  • EM Schwiebert et al.

    Both CFTR and outwardly rectifying chloride channels contribute to cAMP-stimulated whole cell chloride currents

    Am J Physiol

    (1994)
  • MR Knowles et al.

    Mucus clearance as a primary innate defense mechanism for mammalian airways

    J Clin Invest

    (2002)
  • GB Pier et al.

    How mutant CFTR may contribute toPseudomonas aeruginosa infection in cystic fibrosis

    Am J Respir Crit Care Med

    (1996)
  • RG Crystal

    Gene therapy strategies for pulmonary disease

    Am J Med

    (1992)
  • MA Rosenfeld et al.

    Gene therapy for pulmonary diseases

    Pathol Biol (Paris)

    (1993)
  • TR Flotte et al.

    Gene expression from adeno-associated virus vectors in airway epithelial cells

    Am J Respir Cell Mol Biol

    (1992)
  • TR Flotte et al.

    Stablein vivo expression of the cystic fibrosis transmembrane conductance regulator with an adeno-associated virus vector

    Proc Natl Acad Sci U S A

    (1993)
  • Cited by (325)

    View all citing articles on Scopus

    Supported by the Cystic Fibrosis Foundation, the General Clinical Research Centers Program, NCRR, Targeted Genetics Corporation, the Ross Mosier Fund, and the Berger-Raynolds Fund.

    Dr. Heald is an employee of Targeted Genetics Corporation, manufacturer of the gene vector used in this study.

    View full text