Arcturus Therapeutics Shares Plummet on Dual Clinical Setbacks

Arcturus Therapeutics Holdings Inc. witnessed a dramatic collapse in its share price Wednesday, with the stock losing approximately half its value following disappointing developments across two major programs. The biopharmaceutical company faced a severe market reaction after reporting mixed interim Phase 2 results for its cystic fibrosis treatment ARCT-032 and encountering unexpected regulatory hurdles for its COVID-19 vaccine candidate.

Regulatory and Clinical Challenges Erode Investor Confidence

The mid-stage trial for ARCT-032, while demonstrating acceptable safety and tolerability profiles, failed to achieve its primary endpoint of improved lung function. Although imaging data revealed what researchers described as “encouraging” reductions in mucus volume for four of six patients, these secondary outcomes failed to compensate for the missed primary objective.

Compounding the negative news, the U.S. Food and Drug Administration unexpectedly requested additional clinical data for the company’s COVID-19 vaccine, KOSTAIVE®. This regulatory reversal represents a significant commercialization delay for what had been considered a key asset, substantially increasing uncertainty around the company’s near-term prospects.

Market Analysts Revise Outlook Following Announcement

Financial institutions responded swiftly to the twin disappointments with a series of downgrades and price target reductions:

• Wells Fargo slashed its target from $42 to $20 per share
• BTIG Research reduced its projection from $48 to $23
• Guggenheim and Citigroup both downgraded to “Neutral” ratings
• Leerink Partners implemented the most drastic cut, lowering its target from $54 to $17

These coordinated adjustments reflect a fundamental reassessment of Arcturus’s short-term valuation drivers and growth trajectory.

Should investors sell immediately? Or is it worth buying Arcturus Therapeutics Holdings?

Potential Bright Spots Amid the Selloff

Despite the significant setbacks, the company maintains other development programs that continue to advance. ARCT-810, targeting ornithine transcarbamylase deficiency, has demonstrated early biomarker improvements and remains on track for Phase 3 trials in 2026. The collaboration with CSL Seqirus continues unaffected, and the company’s cash position is projected to fund operations through 2028.

Notably, Cathie Wood’s ARK Investment Management acquired nearly 300,000 shares on Thursday, signaling continued institutional confidence despite the dramatic price decline.

Critical Milestones on the Horizon

Investor attention now turns to several upcoming catalysts that could potentially restore value:

• 12-week safety study results for ARCT-032 expected in the first half of 2026
• Regulatory alignment for the Phase 3 OTCD program, also anticipated in 2026
• Immunogenicity data for the pandemic influenza vaccine candidate due in the fourth quarter of 2025

Whether Arcturus can regain market confidence will depend heavily on these future clinical readouts, which will determine if Wednesday’s collapse represented an overreaction or the beginning of a sustained downturn.