---
schema_version: "secwatch.filing_event.v1"
accession: "0001193805-25-001247"
form_type: "8-K"
ticker: "ARCT"
cik: "0001768224"
company_name: "Arcturus Therapeutics Holdings Inc."
filed_at: "2025-08-29T23:59:59+00:00"
generated_at: "2026-05-17T09:15:14.566028+00:00"
event_type: "regulatory"
sentiment: "positive"
materiality_score: 0.65
calibrated_materiality_score: 0.65
confidence: "high"
source: SEC EDGAR
---

# Meiji Seika Pharma receives Japan approval for two-dose vial of KOSTAIVE® COVID-19 vaccine

## Summary
- Approval granted August 28, 2025 for new two-dose vial presentation of KOSTAIVE® (ARCT-2301) in Japan.
- Vaccine targets SARS-CoV-2 Omicron sub lineage JN.1 variant XEC; induces neutralizing antibodies against multiple variants.
- Meiji Seika Pharma plans to begin supply of the new presentation starting late September 2025.
- Non-clinical data shows neutralizing antibodies against JN.1, XEC, LP.8.1, XFG, and NB.1.8.1 variants.
- Distribution in Japan is under a prior agreement between Meiji and CSL Seqirus, partner of Arcturus.

## SEC filing metadata
- accession: 0001193805-25-001247
- form_type: 8-K
- ticker: ARCT
- cik: 0001768224
- company_name: Arcturus Therapeutics Holdings Inc.
- filed_at: 2025-08-29T23:59:59+00:00
- event_type: regulatory
- sentiment: positive
- materiality_score: 0.65
- calibrated_materiality_score: 0.65
- confidence: high
- sec_items: 7.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1768224/000119380525001247/0001193805-25-001247-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1768224/000119380525001247/e664805_8k-arct.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193805-25-001247
- JSON: https://secwatch.observer/filing/0001193805-25-001247.json
- Plain text: https://secwatch.observer/filing/0001193805-25-001247.txt

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