---
schema_version: "secwatch.filing_event.v1"
accession: "0001193805-24-000392"
form_type: "8-K"
ticker: "ARCT"
cik: "0001768224"
company_name: "Arcturus Therapeutics Holdings Inc."
filed_at: "2024-03-19T23:59:59+00:00"
generated_at: "2026-06-04T13:36:33.174558+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.7
calibrated_materiality_score: 0.7
confidence: "high"
source: SEC EDGAR
---

# Arcturus partner Meiji reports Phase III success for bivalent COVID-19 booster in Japan

## Summary
- Bivalent ARCT-2301 (Kostaive) met primary endpoint of non-inferiority vs COMIRNATY bivalent in GMT ratio and SRR difference.
- Superiority against Omicron BA.4/5 and Wuhan strain also confirmed in the phase III study in healthy Japanese adults.
- No causally-related severe or serious adverse events reported; safety profile supports platform.
- Study conducted by Meiji under distribution agreement with CSL Seqirus for Japan market.

## SEC filing metadata
- accession: 0001193805-24-000392
- form_type: 8-K
- ticker: ARCT
- cik: 0001768224
- company_name: Arcturus Therapeutics Holdings Inc.
- filed_at: 2024-03-19T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.7
- calibrated_materiality_score: 0.7
- confidence: high
- sec_items: 7.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1768224/000119380524000392/0001193805-24-000392-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1768224/000119380524000392/e619378_8k-arct.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193805-24-000392
- JSON: https://secwatch.observer/filing/0001193805-24-000392.json
- Plain text: https://secwatch.observer/filing/0001193805-24-000392.txt

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