Cystic fibrosis (CF) patients treated with Kalydeco (ivacaftor) who have the G551D mutation reported better health-related quality of life (HRQoL) and symptom relief than those on standard treatment who carry the F508del mutation in the CFTR gene, according to a real-world study.
The research, “Patient-reported outcomes in patients with cystic fibrosis with a G551D mutation on ivacaftor treatment: results from a cross-sectional study,” was published in the journal BMC Pulmonary Medicine.
CF patients with the G551D mutation in the CFTR gene have shown improvements in lung function, body weight, and HRQoL when treated with Vertex Pharmaceuticals’ Kalydeco over approximately three years in clinical trials. However, data from real-world studies are still limited.
Aiming to address this gap, an international team of researchers compared 72 CF patients on Kalydeco for at least three months who had the G551D mutation on at least one gene copy — the group first covered with this therapy in the United States — to 137 patients with F508del, the most common CFTR mutation, receiving standard-of-care treatment prior to the availability of Orkambi (lumacaftor/ivacaftor, also marketed by Vertex).
The impact on HRQoL was evaluated with the Cystic Fibrosis Questionnaire-Revised (CFQ-R), which incorporates general assessments — vitality, health perceptions, and physical, emotional, social and role functioning — as well as domains specific to CF (body image, eating, treatment burden, and respiratory and digestive symptoms); and the EuroQol 5-dimensions 5-level questionnaire (EQ-5D-5L), which assesses mobility, self-care, usual activities, pain/discomfort, and anxiety or depression. It also includes a scale to determine self-rated health. The Activity Impairment Questionnaire (WPAI) measures work or school productivity.
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The study gathered responses from CF patients age 12 and older, and from caregivers of patients ages 6–11 from France, the United Kingdom, Germany, Australia, and Ireland. Three versions of the patient-reported outcome measures were used for specific age ranges.
Overall, the mean patient age was 24.3 years, and 56% were male.
The group on Kalydeco had a significantly higher proportion of females (60.3% vs. 35.2%) than the standard care group, a higher mean percent predicted forced expiratory volume in one second (a measure of lung function; 79.8 vs. 70.7 percentage points), fewer patients with pancreatic insufficiency (80.3% vs. 92.0%), and a lower mean number of comorbidities (1.5 vs. 2.0).
The mean duration of treatment with Kalydeco was 21.8 months.
After accounting for differences in lung function, sex, and comorbidities, the CFQ-R results showed better scores in G551D carriers on Kalydeco than in patients with F508del and on standard treatment, in both generic and disease-specific measures. Of note, higher CFQ-R scores represent a better quality of life.
Specifically, better scores associated with Kalydeco were found in respiratory symptoms, digestive symptoms, eating, treatment burden, and physical functioning. The 6–11 and 14–up age ranges also showed better scores in weight, health perceptions, and vitality domains if treated with Kalydeco.
Regarding the EQ-5D-5L tool, treatment with Kalydeco led to better scores of mobility, usual activities, pain/discomfort, and anxiety/depression. Results of school productivity loss and daily activity impairment, as assessed with the WPAI questionnaire, also favored Kalydeco, but these were not statistically different comparing the two groups.
Overall, “patients with CF and a G551D-CFTR mutation … receiving [Kalydeco] in real-world settings reported better generic and disease-specific HRQoL, better school productivity, and better symptomatology than patients with CF who are homozygous for F508del-CFTR and receiving [standard of care] in multiple domains,” the researchers stated.
“These findings lend additional real-world support to the HRQoL benefit of [Kalydeco] previously described in clinical trials,” they added.
Of note, one of the study’s authors is a current employee, while another is a former employee of Vertex.