Arcturus Therapeutics released interim Phase 2 data for its inhaled mRNA candidate ARCT‑032 in Class I cystic fibrosis patients that showed no meaningful improvement in FEV1 at Day 28 and prompted a sharp share price decline. The company reported tolerability and preliminary signals—such as reductions in mucus burden in some patients—that it described as encouraging but insufficient against primary efficacy expectations. Arcturus will continue higher‑dose cohorts and plans a longer safety and preliminary efficacy study. Management emphasized safety data and stated plans for additional testing that may clarify whether mucociliary or other biological effects warrant further development.