Ivacaftor Safe in Cystic Fibrosis With Non-G551D Gating Mutations

Ivacaftor is safe and effective in patients with cystic fibrosis (CF) who have severe lung disease and non-G551D gating mutations, according to study results published in Pediatric Pulmonology.¹

The efficacy of ivacaftor has been assessed mostly in patients with CF who have gating mutations and severe lung disease with the G551D mutation.^2-5 A significant percentage of patients with CF have severe lung involvement, but these patients are usually excluded from phase 3 clinical trials and thus, the effectiveness of ivacaftor in this population has not been fully confirmed.

Researchers collected data from Italian CF centers with 13 patients enrolled in an ivacaftor compassionate use program and data were collected for a year before and after ivacaftor treatment was initiated (median 320 days). They found that mean percent predicted forced expiratory volume in 1 second increased from 35.1% before treatment to 46.6% after 12 months of treatment.

In addition, the mean distance of the 6-minute walking test improved significantly from 535.1 meters before treatment to 611.6 meters after 12 months of treatment (P =.002). The number of pulmonary exacerbations decreased significantly (57 in the year before ivacaftor vs 28 in the year after ivacaftor; P =.0048) and 5 of the 13 patients had no exacerbations in the 12 months after starting treatment. They also found that median weight increased significantly (P =.0031) and mean sweat chloride concentration decreased significantly (P <.0001) after 12 months.

“In conclusion, this study showed that treatment with ivacaftor was safe and resulted in clinically and statistically significant and sustained improvements in multiple parameters in patients with CF carrying non‐G551D gating mutations and severe lung disease, pointing out that drugs modulating CF [transmembrane-conductase regulator] can benefit patients with CF with severe lung disease” stated the investigators.¹

References

1. Salvatore D, Carnovale V, Iacotucci P, et al. Effectiveness of ivacaftor in severe cystic fibrosis patients and non‐G551D gating mutations [published online June 25, 2019]. Pediatr Pulmonol. doi:10.1002/ppul.24424
2. Hebestreit H, Sauer‐Heilborn A, Fischer R, Käding M, Mainz JG. Effects of ivacaftor on severely ill patients with cystic fibrosis carrying a G551D mutation. J Cyst Fibros. 2013;12(6):599‐603.
3. Wood ME, Smith DJ, Reid DW, Masel PJ, France MW, Bell SC. Ivacaftor in severe cystic fibrosis lung disease and a G551D mutation. Respirol Case Rep. 2013;1(2):52‐54.
4. Barry PJ, Plant BJ, Nair A, et al. Effects of ivacaftor in cystic fibrosis patients who carry the G551D mutation and have severe lung disease. CHEST. 2014;146(1):152‐158.
5. Taylor‐Cousar J, Niknian M, Gilmartin G, Pilewski JM; for the VX11‐770‐901 investigators. Effect of ivacaftor in patients with advanced cystic fibrosis and a G551D‐CFTR mutation: safety and efficacy in an expanded access program in the United States. J Cyst Fibros. 2016;15(1):116‐122.