Arcturus Therapeutics Holdings Inc.

Item 1. Legal Proceedings.

From time to time, we may be involved in various legal proceedings and subject to claims that arise in the ordinary course of business, and the results of litigation and claims are inherently unpredictable and uncertain. Other than as set forth below, we are not currently a party to any material legal proceedings.

On September 23, 2025, we filed a lawsuit against AbbVie Inc., Capstan Therapeutics, Inc. and other defendants in the United States District Court for the Southern District of California, asserting claims for trade secret misappropriation and breach of contract. We filed an Amended Complaint on April 13, 2026, against the same defendants and asserting the same claims. Defendants answered the Amended Complaint on May 11, 2026. On the same date, Capstan Therapeutics asserted counterclaims for trade secret misappropriation against us and two of our employees, and for breach of contract against the two employees. We and the two employees answered the counterclaims on June 12, 2026. The parties are presently engaged in motion practice regarding identification of trade secret claims and have served discovery upon one another. The Court has not yet set a trial date.

On August 3, 2026, we entered into a Termination and Settlement Agreement with CSL Seqirus, pursuant to which the parties agreed to dismiss the arbitration with CSL Seqirus that was before the International Chamber of Commerce (the “ICC”), seeking payment of a milestone under the CSL Collaboration Agreement based on the European Commission’s grant of marketing authorization for a presentation of KOSTAIVE® in the European Union (“EU Milestone Payment”), and exchanged mutual releases of claims, including those related to the EU Milestone Payment. On August 5, 2026, we informed the ICC that we were dismissing the arbitration because of the resolution reached with CSL Seqirus. That same day, the arbitral tribunal acknowledged dismissal of the arbitration.