Hemoglobin Levels in Children Treated for Cystic Fibrosis with CFTR Modulators: A Single Center Retrospective Study

TL;DR

This study examines how CFTR modulators affect hemoglobin levels in children with cystic fibrosis, finding different patterns between two treatments.

Contribution

The study provides new insights into hemoglobin changes in pediatric cystic fibrosis patients treated with Elexacaftor/Tezacaftor/Ivacaftor.

Findings

LI treatment caused a significant and sustained increase in hemoglobin levels over one year.

ETI treatment initially reduced hemoglobin, which returned to baseline after one month.

ETI also caused temporary increases in potassium and bilirubin levels that persisted for a year.

Abstract

Background: An increase in hemoglobin (Hb) has been reported in subjects with CF treated with the CFTR modulator Ivacaftor and with the combination Lumacaftor/Ivacaftor (LI), while the literature about the impact of Elexacaftor/Tezacaftor/Ivacaftor (ETI) on Hb levels in the pediatric population is lacking. Materials and Methods: We retrospectively evaluated Hb levels in 35 subjects with CF (18 males, median age: 8 years; interquartile range (IQR): 6–13 years) treated with LI and 60 (24 males, median age: 10 years; IQR: 6–14 years) treated with ETI. For each subject we considered the values of Hb, serum potassium, total bilirubin (TB), and conjugated bilirubin (CB) at baseline, after 3 days, and 1, 3, 6, 9, and 12 months from the start of treatment. Results: In subjects with CF treated with LI, we observed a significant increase in Hb values 3 days after the introduction of the drug, which remained constant throughout the year of treatment. In subjects treated with ETI, a significant decrease in Hb was observed 3 days after the first dose up to 1 month. At 6 months, Hb returned to pre-treatment values remaining stable for up to 12 months. At 3 days of treatment, we also observed a significant increase in serum potassium, which returned to normal at one month, while both TB and CB values significantly increased at 3 days of treatment and remained significantly higher for the whole one-year period of ETI therapy. Conclusions: We confirmed an increase in Hb values over time in subjects treated with LI. While the Hb response in those treated with ETI showed a transient reduction that lasted for one month, this may have depended on hemolysis, and returned to pre-treatment levels. Further studies will clarify the mechanisms that govern changes in Hb in subjects with CF treated with ETI.