TOPLINE

Ivacaftor therapy was associated with accelerated linear growth and improved lung function in children and young adults with cystic fibrosis (CF) vs untreated control individuals, resulting in greater attained height and forced vital capacity (FVC) by age 20 years. These benefits were more pronounced among participants with severe CFTR variants.

METHODOLOGY

• Researchers conducted a retrospective cohort analysis in the US to assess whether ivacaftor therapy enhanced linear growth and lung function in children and young adults with CF.
• Data of 18,193 participants aged 6-20 years (49.1% female individuals) were sourced from the Cystic Fibrosis Foundation Patient Registry from 2012 to 2020; of them, 1794 received ivacaftor monotherapy and 16,399 did not receive any modulator therapy and served as control individuals.
• Analyses were conducted across five age groups (6.0-11.5, 11.5-13.5, 13.5-15.5, 15.5-17.5, and 17.5-20 years) to assess differences in lung growth during the peripubertal and pubertal periods.
• Height and lung function (assessed using FVC) were tracked over time and compared across groups stratified by age, sex, and CFTR variants; how ivacaftor affected FVC both directly and indirectly through its effects on height growth was also assessed.

TAKEAWAY

• At age 20 years, participants treated with ivacaftor had a significantly higher mean FVC than control individuals, with a mean difference of 662 mL in boys and 530 mL in girls (P < .0001 for both); similar mean differences were observed in those with severe CFTR variants (P < .0001 for both).
• Height was greater in the ivacaftor group than in the control group across all age groups (6-20 years) and both sexes. Among those with severe CFTR variants, both ivacaftor-treated girls (2.3 cm) and boys (2.6 cm) achieved greater height than control individuals at age 20 years (P < .0001 for both).
• Height-independent gains in FVC occurred predominantly during the peripubertal period (6-13 years) for both sexes, with ivacaftor therapy remaining a significant predictor of improved FVC across all age groups.
• Additionally, sensitivity analyses suggested that treatment with ivacaftor was linked to an increase in absolute FVC partly through improved linear growth and more normal maturation.

IN PRACTICE

“In summary, this study provides strong evidence that CFTR modulators can optimize somatic and pulmonary development when initiated in childhood. As such, it reinforces the rationale for early initiation of modulators to unlock the biological potential of children with CF,” the authors wrote.

SOURCE

The study was led by Jennifer S. Guimbellot, University of Arkansas for Medical Sciences, Arkansas Children’s Research Institute in Little Rock, Arkansas. It was published online on July 2, 2026, in the European Respiratory Journal.

LIMITATIONS

The retrospective design precluded establishing causal conclusions, and the lack of a healthy non-CF control group limited benchmarking of attainment of absolute height and lung function. The registry does not capture medication adherence. FVC served as a surrogate for lung growth; therefore, the results should be considered spirometric rather than a direct measure of total lung capacity, and classification of CFTR variants (severe or residual) didn’t fully capture individual phenotypic variability.

DISCLOSURES

This study received support from the Cystic Fibrosis Foundation as well as the National Heart, Lung, and Blood Institute/National Institutes of Health. Two authors disclosed receiving consulting fees from Vertex Pharmaceuticals. All other authors reported having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.