Arcturus Therapeutics Stock Crashes 60% on Underwhelming mRNA Cystic Fibrosis Drug Results

Arcturus Therapeutics' stock plummeted by about 55–60% after interim results from a phase 2 trial of its inhaled mRNA therapy, ARCT-032, for cystic fibrosis were viewed as underwhelming1 3 5 8.

The interim analysis showed no meaningful improvement in forced expiratory volume (FEV1), the key lung function measure, after 28 days of treatment among six adults with Class I cystic fibrosis3 7.

Management and investors had hoped for a 3% FEV1 increase, but this target was not met, raising doubts about the drug's potential for sustained benefits in lung function3.

Despite disappointing efficacy on the primary efficacy measure, ARCT-032 was generally found to be safe and well-tolerated, with reductions in mucus plugs observed for some participants1 2.

The main aim of the trial was to assess safety and adverse events, which were generally mild and manageable1 2.

Arcturus' market capitalization dropped to roughly $271–288 million, with shares falling from $23.16 to around $10–11.50 on news of the trial1 3 4 5 8.

The outcome raised questions among investors and analysts about the future prospects of ARCT-032 and mRNA therapy for cystic fibrosis3 6.

The company continues to focus on RNA/mRNA medicines for rare diseases, and additional studies for ARCT-032 may be needed to demonstrate efficacy in lung function or in larger patient groups1 2.