Bringing new treatments to the bedside in cystic fibrosis

Multicenter analysis of body mass index, lung function, and sputum microbiology in primary ciliary dyskinesia

BACKGROUND

No studies longitudinally, simultaneously assessed body mass index (BMI) and spirometry in primary ciliary dyskinesia (PCD).

METHODS

We determined BMI and spirometry in 158 PCD children and adolescents from London, UK (n = 75), Naples, Italy (n = 23) and Copenhagen, Denmark (n = 60) at first presentation and during follow-up. Annual BMI and spirometry were prospectively collected and analyzed over blocks of 2, 4, and 6 consecutive years. Sputum pathogens were recorded.

RESULTS

Age at first spirometry was 8.7 years (range, 4.2-17.4). Mean Z scores of first measured BMI, FEV1, FVC, and FEF(25-75) were 0.01, -1.37, -0.84, and -1.68, respectively. First spirometry was not more frequently impaired in patients referred at age ≥6 years than in those referred at preschool age (P = 0.13). There were no differences in slopes for BMI, FEV1, FVC, or FEF(25-75) over any time block. H. influenzae was the most common pathogen, isolated at least once in 65% of patients. P. aeruginosa was found in 58 subjects (37%) of whom 8 (5%) were chronically infected. Neither pathogens was associated with spirometry changes.

CONCLUSIONS

Preschool referral to a PCD center was not associated with better spirometry or BMI. PCD children and adolescents receiving centralized care show steady BMI and spirometry during medium term follow-up. There was a high prevalence of Pseudomonas aeruginosa infection, but the evolution of spirometry or BMI was not affected by this microorganism in medium term. Despite our longitudinal analysis showed no differences between the three centers, the assessment of spirometry and BMI over time represents a quality improvement tool. Future studies are needed to highlight the role of spirometry and BMI in long term PCD management and identify subgroups of patients with a higher risk of early lung failure or nutritional problems.

Pharmacokinetic and pharmacodynamic evaluation of liposomal amikacin for inhalation in cystic fibrosis patients with chronic pseudomonal infection

The pharmacokinetics and pharmacodynamics of a novel liposomal amikacin for inhalation were evaluated in cystic fibrosis patients with chronic pseudomonas infection. Twenty-four patients from two studies received 500 mg of liposomal amikacin by inhalation once daily for 14 days. Serum, sputum, and 24-h urine samples were collected on days 1 and 14 of therapy; pulmonary function tests (PFT) and sputum for quantitative microbiology were assessed at baseline and serially for 14 days. Relationships between amikacin exposure in serum and sputum and absolute change in PFT endpoints and log10 CFU of Pseudomonas aeruginosa from baseline on days 7 and 14 of therapy were assessed. On days 7 and 14, absolute change from baseline in forced expiratory volume in 1 s (FEV1), percent predicted forced expiratory volume in 1 s (FEV1 % predicted), and forced expiratory flow between 25 and 75% of forced vital capacity (FEF(25-75%)) increased by 0.24 (P = 0.002) and 0.13 (P = 0.10) liters, 7.49 (P < 0.001) and 4.38 (P = 0.03), and 0.49 (P < 0.001) and 0.42 (P = 0.02) liters/s, respectively. In addition, relative change from baseline in FEV1 % predicted was 10.8% (P < 0.001) and 5.62% (P = 0.073) on days 7 and 14, respectively. While significant relationships between absolute change in PFT endpoints and the ratio of serum or sputum area under the concentration-time curve to the MIC (AUC/MIC) were not observed, relationships between change in log10 CFU and serum AUC/MIC ratio and change in log10 CFU and absolute changes in all PFT endpoints were significant. Together, these findings likely represent drug effect and warrant the further development of liposomal amikacin for inhalation.

TREX1 DNA exonuclease deficiency, accumulation of single stranded DNA and complex human genetic disorders

Aicardi-Goutieres syndrome (AGS) is an unusual condition that clinically mimics a congenital viral infection. Several genes have recently been implicated in the aetiology of this disorder. One of these genes encodes the DNA exonuclease TREX1. Recent work from Yang, Lindahl and Barnes has provided insight into the cellular consequence of TREX1-deficiency. They found that TREX1-deficiency resulted in the intracellular accumulation of single stranded DNA resulting in chronic activation of the DNA damage response network, even in cells from Trex1-mutated AGS patients. Here, I summarise their findings and discuss them in context with the other AGS causative genes which encode subunits of the RNase H2 complex. I describe mechanisms by which the inappropriate intracellular accumulation of nucleic acid species might deleteriously impact upon normal cell cycle progression. Finally, using the example of Systemic Lupus Erythematosus (SLE), I also summarise the evidence suggesting that the failure to process intermediates of nucleic acid metabolism can result in the activation of uncontrolled autoimmunity.

Advancing outcome measures for the new era of drug development in cystic fibrosis

The growing pipeline of candidate drugs for cystic fibrosis (CF) is challenging clinical trial research. There has been a shift from evaluating drugs aimed at treating the secondary manifestations of CF to evaluating drugs targeted toward the primary prevention of chronic lung disease. As CF is an orphan disease, there is a fundamental need to assess new therapies efficiently and accurately by mechanisms that best use the number of available patients. This need can be addressed with the continued advancement and refinement of CF outcome measures. We begin by presenting an overview of the outcome measures currently used in CF clinical studies, defined and categorized in terms of one of the three main classes of endpoints: clinical efficacy measures, surrogate endpoints, and biomarkers. To move forward efficiently, clinical research in CF is dependent on the development of new outcomes able to capture biologic and clinical response to novel therapeutic approaches. We conclude with a discussion of the criteria by which all new outcome measures should be evaluated. A systematic, rigorous approach to outcome measure development is needed to provide the tools necessary for evaluating new therapies and moving drugs out of the pipeline and into the CF clinic.

Disease modifying genes in cystic fibrosis: therapeutic option or one-way road?

Cystic fibrosis (CF) is the most common genetic disease among Caucasians and is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. CF affects multiple organs but lung disease is the major determinant for morbidity and mortality. Many studies have focussed on the correlation between CFTR genotype and severity of disease. Since patients with identical CFTR mutations often show considerable variability in disease progression, genes other than CFTR are thought to have the potential to modify the course of lung disease in CF patients. Therefore, identification of CF-modifying genes has become the goal of several studies over the last 15 years. Pharmaceutical approaches for CF lung disease have been developed regardless of the underlying genetic defect and in general target symptoms such as airway obstruction and treatment of bacterial infection. Analysing the pathophysiological processes of modifiers may lead to the discovery of pathways involved in CF pathophysiology and possibly to the design of new therapeutics. The purpose of this review is not only to list potential CFTR modifier genes, but also to discuss new therapeutic strategies that could be derived from knowledge of these CF modifiers.

Effect of tolerance induction to immunodominant T-cell epitopes of Sendai virus on gene expression following repeat administration to lung

Sendai virus (SeV) is able to transfect airway epithelial cells efficiently in vivo. However, as with other viral vectors, repeated administration leads to reduced gene expression. We have investigated the impact of inducing immunological tolerance to immunodominant T-cell epitopes on gene expression following repeated administration. Immunodominant CD4 and CD8 T-cell peptide epitopes of SeV were administered to C57BL/6 mice intranasally 10 days before the first virus administration with transmission-incompetent F-protein-deleted DeltaF/SeV-GFP. At 21 days after the first virus administration, mice were again transfected with DeltaF/SeV. To avoid interference of anti-GFP antibodies, the second transfection was carried out with DeltaF/SeV-lacZ. At 2 days after the final transfection lung beta-galactosidase expression, T-cell proliferation and antibody responses were measured. A state of 'split tolerance' was achieved with reduced T-cell proliferation, but no impact on antiviral antibody production. There was no enhancement of expression on repeat administration; instead, T-cell tolerance was, paradoxically, associated with a more profound extinction of viral expression. Multiple immune mechanisms operate to eradicate viruses from the lung, and these findings indicate that impeding the adaptive T-cell response to the immunodominant viral epitope is not sufficient to prevent the process.

The physical, psychological, and social implications of caring for the pregnant patient and newborn with cystic fibrosis

Cystic fibrosis (CF) involves the exocrine glands and epithelial tissues of the pancreas, sweat glands, and mucus glands in the respiratory, digestive, and reproductive tracts. Significant pulmonary disease, poor nutritional status, and pulmonary hypertension are results of chronic infections. When the woman with CF becomes pregnant, her body may find it difficult to adjust to the normal physiological changes of pregnancy, with the pulmonary, cardiovascular, and nutritional status being particularly stressed. Both the mother and the fetus are at a significant risk for increased morbidity and mortality. The woman whose life and pregnancy are compromised by CF and/or the newborn who is diagnosed with CF offer the nurse an extremely challenging situation--one in which physical and psychological care are proportional in importance. As part of the healthcare team, which includes a perinatologist, a pulmonary medicine specialist, a neonatologist, an anesthesiologist, a geneticist, a dietitian, a respiratory therapist, a social worker, an ethicist, and perhaps a clergyman, the nurse helps to coordinate and carry out the care needed for a successful outcome.

Identifying novel endpoints for cystic fibrosis clinical trials

Clinical and translational research in cystic fibrosis (CF) is hampered by a lack of biomarkers that can be used to identify promising new therapies. In particular, validated protein biomarkers are needed to evaluate emerging candidate anti-inflammatory and antimicrobial treatments. Noninvasively obtained biomarkers are especially desirable in children where repeatedly sampling the airway is difficult. To more quickly identify and validate candidate protein biomarkers, it will be essential to pursue a phased approach to biomarker development in a large, well-characterized CF patient population. New high-throughput technologies that can simultaneously examine the expression of thousands of genes and proteins are accelerating the discovery of potential biomarkers. It is hoped that individual biomarkers, or more likely a panel of validated markers, will predict clinical outcomes such as susceptibility to rapid disease progression or response to treatment and therefore, greatly improve stratification for future CF clinical trials.

Gene therapy approaches for intervertebral disc degeneration

STUDY DESIGN

Review of the literature concerning the development of gene therapy approaches for the treatment of intervertebral disc degeneration.

OBJECTIVES

To provide an overview of gene therapy principles, summarize the results of completed gene therapy studies, and discuss considerations for the direction of future research.

SUMMARY OF BACKGROUND DATA

Intervertebral disc degeneration is characterized by progressive loss of the proteoglycan matrix in the nucleus pulposus. Exogenous growth factors have been shown to transiently increase matrix synthesis. Gene therapy offers exciting potential to induce and sustain endogenous production of growth factors within the intervertebral disc and thus possibly alter the degenerative course.

METHODS

Published and presented scientific literature was examined.

RESULTS/CONCLUSIONS

Several in vitro and in vivo studies have documented the capacity of gene therapy to favorably modify the biologic functions of intervertebral disc cells with the delivery of the cDNA for various growth factors. Currently, investigators are exploring the efficacy and safety of gene therapy in animal models of degeneration. With promising initial results and an immense potential clinical impact, gene therapy approaches for treatment of intervertebral disc degeneration will continue to receive dedicated research efforts.