Repeated Adeno-Associated Virus Serotype 2 Aerosol-Mediated Cystic Fibrosis Transmembrane Regulator Gene Transfer to the Lungs of Patients With Cystic Fibrosis

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.