---
schema_version: "secwatch.filing_event.v1"
accession: "0001193805-25-001499"
form_type: "8-K"
ticker: "ARCT"
cik: "0001768224"
company_name: "Arcturus Therapeutics Holdings Inc."
filed_at: "2025-10-22T23:59:59+00:00"
generated_at: "2026-05-17T02:47:49.505343+00:00"
event_type: "other_material"
sentiment: "negative"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# Arcturus reports ARCT-032 CF interim data showing mucus reduction; KOSTAIVE BLA submission delayed by FDA

## Summary
- ARCT-032 Phase 2 interim: generally safe/tolerated; 4 of 6 Class I CF patients showed mucus plug/volume reduction after 28 days (10 mg).
- FDA requested delay of KOSTAIVE BLA submission (Sep 5), then required additional clinical endpoint efficacy study per updated COVID-19 framework.
- CSL Seqirus submitted KOSTAIVE MAA to UK MHRA in June 2025; approval expected Q1 2026, but not assured.
- Company filed lawsuit Sep 23, 2025 against AbbVie and Capstan Therapeutics for trade secret misappropriation and breach of contract.
- 12-week safety/efficacy study of ARCT-032 in up to 20 CF participants planned to start first half of 2026.

## SEC filing metadata
- accession: 0001193805-25-001499
- form_type: 8-K
- ticker: ARCT
- cik: 0001768224
- company_name: Arcturus Therapeutics Holdings Inc.
- filed_at: 2025-10-22T23:59:59+00:00
- event_type: other_material
- sentiment: negative
- materiality_score: 0.75
- calibrated_materiality_score: 0.75
- confidence: high
- sec_items: 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1768224/000119380525001499/0001193805-25-001499-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1768224/000119380525001499/e664913_8k-arct.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193805-25-001499
- JSON: https://secwatch.observer/filing/0001193805-25-001499.json
- Plain text: https://secwatch.observer/filing/0001193805-25-001499.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.