Arcturus Therapeutics released interim Phase 2 data for ARCT-032, an inhaled mRNA therapy for Class I cystic fibrosis, showing no meaningful improvement in forced expiratory volume in one second (FEV1) at Day 28 in the 10 mg cohort. The small cohort readout prompted a sharp market reaction and a collapse in Arcturus’s share price. Management highlighted safety tolerability and early signals (reduced mucus burden in some patients) but acknowledged that primary efficacy benchmarks were not met and outlined further dose-escalation and longer studies.