Previously, IVA alone (Kalydeco®) could cause a larger alteration in plasma HE4 (−14.4 pmol/L vs−10.7 pmol/L) in a cohort with CF patients bearing at least one p.Gly551Asp-CFTR variant in trans (the Class III CFTR variant), since the mean delta ppFEV1 was also higher (7.0%) by 6 months of treatment in selected GOAL study participants [16] compared to PROSPECT study participants (bearing Class II CFTR variant p.Phe508del), with a mean delta ppFEV1 of only 2.6% [17]. Here, CFTR is linked to cystic fibrosis.