Arcturus Therapeutics disclosed interim results from a Phase 2 study of ARCT-032, an inhaled mRNA therapy for Class I cystic fibrosis (CF), showing no meaningful improvement in forced expiratory volume (FEV1) in the first cohort. The company reported the measure did not meet the pre‑specified benchmark and the stock plunged on the news. Management said safety signals remain acceptable and cited early reductions in mucus burden in some patients; the company is continuing dose-escalation cohorts and plans a longer safety and efficacy study. Analysts noted the FEV1 readout was a secondary endpoint and urged caution in interpreting early cohort data. Arcturus framed the result as a mixed signal — limited functional gains in this small cohort but possible biomarker improvements — and reiterated plans for additional cohorts and a 12‑week study to further define activity and tolerability.