Arcturus Therapeutics released interim results from a Phase 2 study of ARCT‑032, its inhaled mRNA therapy for cystic fibrosis, and the data did not show meaningful improvement in lung function (FEV1) at the prespecified comparator. The company emphasized the safety profile but conceded efficacy signals were weak in the first cohorts. The open‑label, ascending‑dose study evaluated Class I CF patients and focused on safety as the primary endpoint; secondary measures including FEV1 failed to meet management’s internal expectations. Arcturus cited encouraging reductions in mucus burden for some participants and plans ongoing cohorts at higher doses and a 12‑week safety/efficacy study in up to 20 patients next year. Investors reacted sharply on the interim readout, and the results temper enthusiasm for inhaled mRNA delivery in pulmonary rare diseases until more robust efficacy is demonstrated. Regulatory and commercial prospects will depend on the pending higher‑dose cohorts and confirmatory data.