Theratyping cystic fibrosis patients to guide elexacaftor/tezacaftor/ivacaftor out-of-label prescription

BACKGROUND

Around 20% of people with cystic fibrosis (pwCF) do not have access to the triple combination elexacaftor/tezacaftor/ivacaftor (ETI) in Europe because they do not carry the F508del allele on the CF transmembrane conductance regulator (CFTR) gene. Considering that pwCF carrying rare variants may benefit from ETI, including variants already validated by the US Food and Drug Administration (FDA), a compassionate use programme was launched in France. PwCF were invited to undergo a nasal brushing to investigate whether the pharmacological rescue of CFTR activity by ETI in human nasal epithelial cell (HNEC) cultures was predictive of the clinical response.

METHODS

CFTR activity correction was studied by short-circuit current in HNEC cultures at basal state (dimethyl sulfoxide (DMSO)) and after ETI incubation and expressed as percentage of normal (wild-type (WT)) CFTR activity after sequential addition of forskolin and Inh-172 (ΔI ETI/DMSO%WT).

RESULTS

11 pwCF carried variants eligible for ETI according to the FDA label and 28 carried variants not listed by the FDA. ETI significantly increased CFTR activity of FDA-approved CFTR variants (I601F, G85E, S492F, M1101K, R347P, R74W;V201M;D1270N and H1085R). We point out ETI correction of non-FDA-approved variants, including N1303K, R334W, R1066C, Q552P and terminal splicing variants (4374+1G>A and 4096-3C>G). ΔI ETI/DMSO%WT was significantly correlated to change in percentage predicted forced expiratory volume in 1 s and sweat chloride concentration (p<0.0001 for both). G85E, R74W;V201M;D1270N, Q552P and M1101K were rescued more efficiently by other CFTR modulator combinations than ETI.

CONCLUSIONS

Primary nasal epithelial cells hold promise for expanding the prescription of CFTR modulators in pwCF carrying rare mutants. Additional variants should be discussed for ETI indication.

Predictive factors for lumacaftor/ivacaftor clinical response

BACKGROUND

Ivacaftor-lumacaftor combination therapy corrects the F508 del-CFTR mutated protein which causes Cystic Fibrosis. The clinical response of the patients treated with the combination therapy is highly variable. This study aimed to determine factors involved in the individual's response to lumacaftor-ivacaftor therapy.

METHODS

Sweat test was assessed at baseline and after 6 months of ivacaftor-lumacaftor treatment in 41 homozygous F508del children and young adults. β-adrenergic peak sweat secretion, nasal potential difference (NPD) and intestinal current measurements (ICM) were performed in patients accepting these tests. Seric level of lumacaftor and ivacaftor were determined and additional CFTR variant were searched.

RESULTS

Sweat chloride concentration significantly decreased after treatment, whereas the β-adrenergic peak sweat response did not vary in 9 patients who underwent these tests. The average level of F508del-CFTR activity rescue reached up to 15% of the normal level in intestinal epithelium, as studied by ICM in 12 patients (p = .03) and 20% of normal in the nasal epithelium in NPD tests performed in 21 patients (NS). There was no significant correlation between these changes and improvements in FEV₁ at 6 months. Serum drug levels did not correlate with changes in FEV₁, BMI-Zscore or other CFTR activity biomarkers. Additional exonic variants were identified in 4 patients. The F87L-I1027T-F508del-CFTR complex allele abolished the lumacaftor corrector effect.

CONCLUSION

This observational study investigates a number of potential factors linked to the clinical response of F508del homozygous patients treated with lumacaftor-ivacaftor combination therapy. Lumacaftor and ivacaftor blood levels are not associated with the clinical response. Additional exonic variants may influence protein correction.

Persistent Bordetella bronchiseptica infection in a child with cystic fibrosis: Relationship to bacterial phenotype

Bordetella bronchiseptica is an opportunistic bacteria infecting the respiratory tract of patients with cystic fibrosis. We present a case of B. bronchiseptica chronic pulmonary infection and documentation of some phenotypic attributes of the clinical isolates allowing the microorganism to induce progressive respiratory degradation and chronic sputum colonization. We recommend implementing adequate treatment aiming eradication from the first isolation of this bacterium. We advise for practices that minimize opportunities for zoonotic transmission of B. bronchiseptica from family pets.

Factors associated with humoral immune response to pandemic A/H1N1(v) 2009 influenza vaccine in cystic fibrosis

Influenza vaccination is recommended in cystic fibrosis patients. The objective of this study was to assess the immunogenicity of vaccination against 2009 pandemic A/H1N1 influenza and to study the factors associated with the immune response in patients with cystic fibrosis. 122 patients with cystic fibrosis were enrolled in a prospective study and received 1 dose of 2009/H1N1v adjuvanted vaccine, or for children <2 years and lung-transplanted patients, two doses of non-adjuvanted 2009/H1N1v vaccine administered 21 days apart. Hemagglutination inhibition antibodies were assessed before and 21 days after vaccination and at least 6 months after vaccination. After vaccination, 85% of the patients had an influenza antibody titer ≥1:40 and 69% seroconverted. 13% of the transplanted patients seroconverted compared with 72% of the non-transplanted patients. In this latter group, non-adjuvanted vaccine and low body mass index were independently associated with lower response to vaccination. 86% of the non-transplanted patients with normal BMI and receiving adjuvanted vaccine seroconverted. Persistence of seroprotection 10 months after vaccination was found in 50% of the patients. In patients with cystic fibrosis, malnutrition and receipt of non-adjuvanted vaccine were associated with lower immune response to pandemic influenza vaccination. Our data also suggest a potential defect in the immune response to influenza vaccination of patients with cystic fibrosis and raise the question of whether a different immunization strategy is needed.

[Anti Pseudomonas aeruginosa antibiotic therapy in cystic fibrosis (exclusion of macrolides)]

Antibiotherapy is one of the main treatment in cystic fibrosis. Pseudomonas aeruginosa infection is one of the main causes of pulmonary degradation. The chronic sputum colonisation is characterized by the emergence of the mucoid phenotype, the formation of biofilm and the induction of excessive inflammatory response and consecutive tissue lesion. The choice of antibiotics depends on quantitative and qualitative analysis of sputum, bacteria resistance phenotypes and severity of infection. Treatment of P. aeruginosa is different in case of first colonization or chronic infection. In the first case, parenteral antibiotherapy (beta-lactams-aminoglycosids) followed by inhaled antibiotherapy may eradicate the germ. In the other case, superinfections can be treated with parenteral biantibiothérapy (beta-lactams or quinolons and aminoglycosides) during 15 to 21 days. This is associated with a better nutritional and respiratory status and a prolonged survival. Inhaled antibiotics between the courses have decreased the number of superinfections. This prolonged antibiotherapy must be monitored because of possible induction of bacterial resistance, nephrotoxicity and ototoxicity of aminosids and allergy to beta-lactams.

The role of inflammation in childhood asthma

The role of inflammation in adult asthma is well known, involving a cascade of immunological stimulation in which mast cells and eosinophils play pivotal roles. However, the assessment of airway inflammation in children is more difficult as the invasive methods used in adults cannot ethically be used for this purpose alone. Nevertheless, limited data from studies using invasive methodology, and studies using novel non-invasive techniques such as sputum induction and nitrous oxide exhalation, are improving knowledge. The immunopathology in childhood asthma appears to mirror that in adult sufferers. The inflammatory processes are evident at an early age in wheezing infants who later develop asthma, and there are different "wheezing phenotypes" in children with atopic asthma or viral associated wheeze. The mechanisms underlying childhood asthma are dependent not only on increased numbers of inflammatory cells in the airways, but also increased activation of these cells. In vitro data have shown that corticosteroids can inhibit the secretion of proinflammatory compounds from alveolar macrophages, suggesting a potential important role for these agents in halting the development of asthma. Techniques for measuring inflammation in infants need to be refined, in order to provide increased knowledge and accurate monitoring of the disease. It is hoped that this will enable the development of early interventions to minimise the impact of asthma in infants who are identified as being susceptible.