TOPLINE:

The initiation of elexacaftor-tezacaftor-ivacaftor (ETI) therapy was associated with increased serum levels of vitamin D and enhanced the effectiveness of vitamin A supplementation in children with cystic fibrosis.

METHODOLOGY:

• Researchers conducted a retrospective study to determine the impact of ETI therapy on serum levels of fat-soluble vitamins (A, D, and E) in children with cystic fibrosis.
• A total of 56 children with cystic fibrosis (median age at initiation of ETI therapy, 10 years; 69.6% boys) and 262, 257, and 252 complete observations for vitamins A, D, and E, respectively, were included.
• Data on serum vitamin levels and supplementation dosages were collected up to 50 months prior to the initiation of ETI and 31 months post-initiation at seven timepoints: T1 (≥ 13 months pre-initiation), T2 (7-12 months pre-initiation), T3 (1-6 months pre-initiation), T4 (3-6 months post-initiation), T5 (7-12 months post-initiation), T6 (13-18 months post-initiation), and T7 (19-24 months post-initiation).

TAKEAWAY:

• The initiation of ETI was associated with a significant increase in serum vitamin D levels, with a median increase of 19.9 nmol/L in the post-ETI vs pre-ETI period (P < .001).
• A significant interaction was identified between the initiation of ETI therapy and the efficacy of vitamin A supplementation, with a positive association emerging between supplementation dose and serum vitamin A levels in the post-ETI period (P for interaction = .008).
• No statistically significant impact of ETI therapy on serum vitamin E levels was observed.

IN PRACTICE:

“[Our] data suggests that a preemptive reduction in supplementation may be warranted for children initiating ETI at earlier ages. This not only mitigates the risk of hypervitaminosis but may also help reduce the treatment burden for patients and their families,” the authors of the study wrote.

SOURCE:

The study was led by Fern Kimber, University of Nottingham, Nottingham, England. It was published online on April 3, 2026, in Pediatric Pulmonology.

LIMITATIONS:

The study was retrospective and relied on routine clinical data. Vitamin supplementation doses were estimated for some patients (based on assumed multivitamin contents), introducing potential measurement bias. The analysis also did not account for seasonal variation in vitamin D sampling and did not capture the clinical reasoning underlying dose changes, which may have affected the interpretation of supplementation trends.

DISCLOSURES:

The study did not receive any funding. One author reported receiving honoraria from Vertex.

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