Henry L. Dorkin

Efficacy of aerosolized tobramycin in patients with cystic fibrosis.

BACKGROUND Direct aerosol delivery of aminoglycosides such as tobramycin to the lower airways of patients with cystic fibrosis may control infection with Pseudomonas aeruginosa and improve pulmonary function, with low systemic toxicity. We conducted a randomized crossover study to evaluate the safety and efficacy of aerosolized tobramycin in patients with cystic fibrosis and P. aeruginosa infections. METHODS Seventy-one patients with stable pulmonary status were recruited from seven U.S. centers for the treatment of cystic fibrosis and randomly assigned to one of two crossover regimens. Group 1 received 600 mg of aerosolized tobramycin for 28 days, followed by half-strength physiologic saline (placebo) for two 28-day period. Group 2 received placebo for 28 days, followed by tobramycin for two 28-day periods. Pulmonary function, the density of P. aeruginosa in sputum, ototoxicity, nephrotoxicity, and the emergence of tobramycin-resistant P. aeruginosa were monitored. RESULTS In the first 28-day period, treatment with tobramycin was associated with an increase in the percentage of the value predicted for forced expiratory volume in one second (9.7 percentage points higher than the value for placebo; P < 0.001), forced vital capacity (6.2 percentage points higher than the value for placebo; P = 0.014), and forced expiratory flow at the midportion of the vital capacity (13.0 percentage points higher than the value for placebo; P < 0.001). A decrease in the density of P. aeruginosa in sputum by a factor of 100 (P < 0.001) was found during all periods of tobramycin administration. Neither ototoxicity nor nephrotoxicity was detected. The frequency of the emergence of tobramycin-resistant bacteria was similar during both tobramycin and placebo administration. CONCLUSIONS The short-term aerosol administration of a high dose of tobramycin in patients with clinically stable cystic fibrosis is an efficacious and safe treatment for endobronchial infection with P. aeruginosa.

Results of a phase IIa study of VX-809, an investigational CFTR corrector compound, in subjects with cystic fibrosis homozygous for the F508del-CFTR mutation

Background VX-809, a cystic fibrosis transmembrane conductance regulator (CFTR) modulator, has been shown to increase the cell surface density of functional F508del-CFTR in vitro. Methods A randomised, double-blind, placebo-controlled study evaluated the safety, tolerability and pharmacodynamics of VX-809 in adult patients with cystic fibrosis (n=89) who were homozygous for the F508del-CFTR mutation. Subjects were randomised to one of four VX-809 28 day dose groups (25, 50, 100 and 200 mg) or matching placebo. Results The type and incidence of adverse events were similar among VX-809- and placebo-treated subjects. Respiratory events were the most commonly reported and led to discontinuation by one subject in each active treatment arm. Pharmacokinetic data supported a once-daily oral dosing regimen. Pharmacodynamic data suggested that VX-809 improved CFTR function in at least one organ (sweat gland). VX-809 reduced elevated sweat chloride values in a dose-dependent manner (p=0.0013) that was statistically significant in the 100 and 200 mg dose groups. There was no statistically significant improvement in CFTR function in the nasal epithelium as measured by nasal potential difference, nor were there statistically significant changes in lung function or patient-reported outcomes. No maturation of immature F508del-CFTR was detected in the subgroup that provided rectal biopsy specimens. Conclusions In this study, VX-809 had a similar adverse event profile to placebo for 28 days in F508del-CFTR homozygous patients, and demonstrated biological activity with positive impact on CFTR function in the sweat gland. Additional data are needed to determine how improvements detected in CFTR function secondary to VX-809 in the sweat gland relate to those measurable in the respiratory tract and to long-term measures of clinical benefit. Clinical trial number NCT00865904

Aerosol and Lobar Administration of a Recombinant Adenovirus to Individuals with Cystic Fibrosis. II. Transfection Efficiency in Airway Epithelium

A phase I clinical trial was conducted in which recombinant adenovirus containing the cystic fibrosis trans-membrane regulator (CFTR) (Ad2/CFTR) was administered by bronchoscopic instillation or aerosolization to the lungs of cystic fibrosis (CF) patients. In this paper, we evaluate the efficiency of Ad2/CFTR-mediated transduction of bronchial airway cells. The ability of an Ad2/CFTR vector to transduce airway cells was first evaluated in patients to whom the vector was administered by bronchoscopic instillation. Cells at the administration site were collected 2 days after treatment by bronchoscopic brushing. Ad2-specific CFTR DNA was detected in four of five individuals by PCR, and Ad2-specific CFTR RNA was detected in three of five individuals by RT-PCR. Ad2/CFTR-mediated transduction of airway epithelial cells was then determined in CF individuals receiving this vector by aerosol inhalation. Ad2-specific CFTR DNA was detected in 13 of 13 individuals 2 days after aerosolization, and in 3 of 5 individuals 7 days after aerosolization. Ad2-specific RNA was detected in 4 of 13 individuals on day 2, but was not detected in the 5 individuals tested on day 7. The percentage of airway epithelial cells containing nuclear-localized vector DNA was < or =2.4% as determined by fluorescence in situ hybridization (FISH). However, in some cases, a high percentage of nonepithelial mononuclear cells or squamous metaplastic epithelial cells was infected with the adenoviral vector. In conclusion, aerosol administration is a feasible means to distribute adenoviral vectors throughout the conducting airways, but improvements in adenovirus-mediated transduction of airway epithelial cells are necessary before gene therapy for CF will be effective.

Aerosol and lobar administration of a recombinant adenovirus to individuals with cystic fibrosis. I. Methods, safety, and clinical implications

Cystic fibrosis (CF), an autosomal recessive disorder resulting from mutations in the cystic fibrosis trans-membrane conductance regulator (CFTR) gene, is the most common lethal genetic illness in the Caucasian population. Gene transfer to airway epithelium, using adenoviruses containing normal CFTR cDNA, leads to transient production of CFTR mRNA and, in some studies, to correction of the airway epithelial ion transport defect caused by dysfunctional CFTR. Inflammatory responses to the adenoviral vector have been reported, particularly at high viral titers. We evaluated the effects of adenovirus-mediated CFTR gene transfer to airway epithelium in 36 subjects with CF (34 individuals, 2 of whom received two separate doses of vector), 20 by lobar instillation and 16 by aerosol administration. Doses ranged from 8 x 10(6) to 2.5 x 10(10) infective units (IU), in 0.5-log increments. After lobar administration of low doses there were occasional reports of cough, low-grade temperature, and myalgias. At the highest lobar dose (2.5 x 10(9) IU) two of three patients had transient myalgias, fever, and increased sputum production with obvious infiltrates on CT scan. After aerosol administration there were no significant systemic symptoms until the 2.5 x 10(10) IU dose, when both patients experienced myalgias and fever that resolved within 24 hr. There were no infiltrates seen on chest CT scans in any of the patients in the aerosol administration group. There were no consistent changes in pulmonary function tests or any significant rise in serum IgG or neutralizing antibodies in patients from either group. Serum, sputum, and nasal cytokines, measured before and after vector administration, showed no correlation with adenoviral dose. Gene transfer to lung cells was inefficient and expression was transient. Cells infected with the vector included mononuclear inflammatory cells as well as cuboidal and columnar epithelial cells. In summary, we found no consistent immune response, no evidence of viral shedding, and no consistent change in pulmonary function in response to adenovirus-mediated CFTR gene transfer. At higher doses there was a mild, nonspecific inflammatory response, as evidenced by fevers and myalgias. Overall, vector administration was tolerated but transfer of CFTR cDNA was inefficient and transgene expression was transient for the doses and method of administration used here.

Respiratory system impedance from 4 to 40 Hz in paralyzed intubated infants with respiratory disease.

To describe the mechanical characteristics of the respiratory system in intubated neonates with respiratory disease, we measured impedance and resistance in six paralyzed intubated infants with respiratory distress syndrome, three of whom also had pulmonary interstitial emphysema. We subtracted the effects of the endotracheal tube after showing that such subtraction was valid. Oscillatory flow was generated from 4 to 40 Hz by a loudspeaker, airway pressure was measured, and flow was calculated from pressure changes in an airtight enclosure mounted behind the flow source (speaker plethysmograph). After subtraction of the endotracheal tube contribution, resistance ranged from 22 to 34 cmH2O liter-1 s; compliance from 0.22 to 0.68 ml/cmH2O; and inertance from 0.0056 to 0.047 cmH2O liter-1 s2. Our results indicate that, for these intubated infants, the mechanics of the respiratory system are well described as resistance, compliance, and inertance in series. Most of the inertance, some of the resistance, and little of the compliance are due to the endotracheal tube. When the contribution of the endotracheal tube is subtracted, the results are descriptive of the subglottal respiratory system. These data characterize the neonatal respiratory system of infants with respiratory distress syndrome (with or without pulmonary interstitial emphysema) in the range of frequencies used during high frequency ventilation.

Increased Nerve-Growth-Factor β-Chain Cross-Reacting Material in Familial Dysautonomia

To determine whether dysautonomia arises from alteration in nerve-growth factor (NGF), we measured serum levels of NGF subunits in normal and dysautonomic subjects using a biologic assay based on neurite outgrowth from chick ganglions, a binding assay based on displacement of radiolabeled betaNGF from rabbit-ganglion microsomes, and radioimmunoassays of chi, gamma and betaNGF subunits via antiserum to mouse NGF polypeptides. A threefold increase (P less than 0.001) in serum antigen levels of the biologically active subunit (betaNGF) was found for dysautonomic as compared with normal subjects. By all other assays, the groups were alike. The marked discrepancy in betaNGF levels between antigenic and functional (biologic and binding) measurements suggests a qualitative abnormaltiy of betaNGF in dysautonomia. Alternatively, elevation of betaNGF antigen can be regarded as secondary to disease. This alternative seems less likely since we must then suppose that the normalcy of functional assays in spurious.

Genetic counseling after implementation of statewide cystic fibrosis newborn screening: Two years' experience in one medical center.

Purpose: To study the follow-up of genetic counseling performed in families with a newborn detected with one cystic fibrosis (CF) mutation in a statewide newborn screening pilot program.Methods: Newborns in Massachusetts with an elevated trypsinogen level on newborn screen who are found to have one mutation for CF on a selected mutation assay undergo sweat testing for CF, and their families receive genetic counseling. The genetic counseling focuses on carrier risk for the parents of the newborn and offers carrier testing. We studied the yield of genetic counseling and the resulting genetic testing performed on the families of infants found to be CF carriers who underwent sweat testing in a single institution.Results: Of 102 newborns evaluated with a single CF mutation, 2 (twins) had sweat test results consistent with CF. A total of 101 families were counseled, and 95 were offered DNA-based CF carrier testing. Eighty-two percent of all parents chose to have CF carrier testing, and in five couples, both members were carriers. One of these couples (whose newborn was only a carrier) had an older child who was unexpectedly found to have CF.Conclusions: Sweat testing of newborns at increased risk for CF in conjunction with genetic counseling for their parents allows identification of infants with CF, finds couples at high risk for having a child with CF, identifies previously undiagnosed siblings with CF, and allows for potential identification of CF carriers in the extended family.

Early Pulmonary Manifestation of Cystic Fibrosis in Children With the ΔF508/R117H-7T Genotype

We report 3 cystic fibrosis newborn screen–positive infants with the ΔF508/R117H-7T genotype who had Pseudomonas aeruginosa detected in oropharyngeal cultures early in life and a fourth who had pulmonary symptoms and Gram-negative growth on multiple oropharyngeal cultures. All 4 patients were followed prospectively from the time of genetic diagnosis. As many regions implement newborn screening for cystic fibrosis, there is concern regarding which mutations should be included in genetic panels used to make the cystic fibrosis diagnosis. Some have recommended that mutations not specifically associated with classic cystic fibrosis be excluded. Our cases highlight the importance of considering keeping so-called mild mutations on cystic fibrosis newborn screening panels and the need to follow children with these mutations closely.

Correction of the cystic fibrosis defect by gene complementation in human intrahepatic biliary epithelial cell lines

BACKGROUND/AIMS Hepatobiliary disease is the second most common cause of mortality in patients with cystic fibrosis (CF). In the liver, only the intrahepatic biliary epithelial (IBE) cells express cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel. The aim of this study was to determine whether human CF-derived IBE cells can be infected with adenovirus and the CF phenotype complemented. METHODS IBE cells were isolated from 2 patients with CF and immortalized using retrovirus transduction of SV40 large T antigen. Immortalized cells were infected with the adenovirus vector Ad2/CFTR2 and assayed 2-31 days postinfection for cyclic adenosine monophosphate (cAMP)-induced halide efflux. Halide efflux was measured in single cells using fluorescence microscopy and the fluorescent probe 6-methoxy-N-(3-sulfopropyl)-quinolinium. RESULTS CF-derived IBE cell lines express biliary specific markers and express no cAMP-inducible halide efflux. Following infection with the adenovirus vector Ad2/CFTR2, a cAMP-induced halide efflux was observed for 31 days, although the number of responsive cells decreased with time. CONCLUSIONS Human CF-IBE cells can be infected by adenovirus and the defective CFTR complemented. The loss of responsive cells with time could be due to loss of construct and/or a reduced growth of cells that are overexpressing CFTR. These CF-IBE cell lines offer an opportunity to determine the mechanisms responsible for hepatobiliary disease in the patients with CF.

Safety of repeated intermittent courses of aerosolized recombinant human deoxyribonuclease in patients with cystic fibrosis

OBJECTIVES To determine the effect of repeated doses of aerosolized recombinant human deoxyribonuclease (rhDNase) on the development of anti-rhDNase antibodies, acute allergic reactions, and pulmonary function in patients with cystic fibrosis. DESIGN A multicenter, open-label study in which 184 patients received 10 mg aerosolized rhDNase twice a day for 14 days followed by a 14-day washout period for a total of 6 treatment cycles. Serial determinations of anti-rhDNase antibodies and pulmonary functions were performed. RESULTS Detectable anti-rhDNase antibodies developed in 16 (8.7%) patients. These patients had no changes in their symptoms from the time they entered the trial. Antibodies detected were all of the IgG isotype. Increases in both forced expired volume in 1 second and forced vital capacity were noted from the beginning to the end of each cycle of treatment returning to baseline during the off-treatment period of each cycle. Seropositivity to rhDNase was not associated with allergic reactions and had no relationship on improvement in pulmonary function. CONCLUSIONS Development of anti-rhDNase antibodies occurred in a small number of patients and was not associated with side effects. Intermittent administration of rhDNase for 24 weeks to patients with cystic fibrosis was well tolerated and was not associated with anaphylaxis in any patient. Pulmonary function improved significantly during the 14-day cycles while rhDNase was administered and returned to baseline when rhDNase was discontinued.