Impacts and New Challenges with Highly Effective Modulator Therapies in Younger Children with Cystic Fibrosis.

Highly effective modulator therapy (HEMT) has been available for adults and young adults aged 12 years and over with cystic fibrosis for approximately 5 years, with real-world evidence (RWE) emerging that confirms the significant impacts of these novel medications in older patient groups. As licensing has been extended to younger children (2 years and above in some jurisdictions), we summarize the clinical experience of these medications in pre-school and school-aged children and compare how changes in the objective markers of the disease can be elucidated in younger children. We also discuss the different incidences and severity of side effect profiles, the efforts to mediate these in younger children, and the particular challenges in introducing novel medications into pediatrics. We speculate on the use of HEMT in younger infants and its potential use in prenatal care.