Arcturus Therapeutics 10-Q gets November 12 filing date after transmission error

The late filing

Arcturus Therapeutics Holdings Inc. (Nasdaq: ARCT) filed a notification of late filing on November 12, 2025 for its quarterly report on Form 10-Q for the period ended September 30, 2025. The Form 12b-25 notice, signed November 10, 2025 by chief financial officer Andy Sassine, says the 10-Q was not filed on time because of a technical transmission error at the time of filing.

The notice says the report will be transmitted after the 5:30 PM Eastern deadline on November 10, 2025. The company expects it to receive a filing date of November 12, 2025. A Form 12b-25 gives a company a short extension when a periodic report cannot be filed without unreasonable effort or expense. For a quarterly report, the extension runs to the fifth calendar day after the due date.

The company answered no when asked whether it expects a significant change in results of operations from the same period a year earlier. It checked yes to having filed all other periodic reports required over the past 12 months. The notice gives no revenue, loss or cash figures for the quarter. It does not describe what the transmission error was.

The company's address is 10285 Science Center Drive in San Diego, California.

What the company sells and develops

Arcturus describes itself as a messenger RNA medicines company focused on infectious disease vaccines and on liver and respiratory rare diseases. Its lead product is KOSTAIVE, a self-amplifying mRNA vaccine. Japan approved KOSTAIVE in 2023 as a vaccine against COVID-19, and the European Commission approved it in February 2025. Commercial sales began in Japan in October 2024, through Meiji Seika Pharma, which is the exclusive partner in Japan of CSL Seqirus.

The company says its self-amplifying technology, called STARR, has been demonstrated to induce a longer-lasting and broader immune response at lower doses than conventional mRNA vaccines. Its LUNAR lipid nanoparticle system is meant to deliver RNA to target tissues. The company calls the Japanese approval a significant milestone that validates both platforms and self-amplifying mRNA more generally.

Its vaccine partnership with CSL Seqirus covers COVID-19, influenza and other infectious diseases. The company says it has established commercial production processes for the COVID-19 vaccine with that partner.

The early pipeline

The company's own rare disease programs are early. ARCT-810, for ornithine transcarbamylase deficiency, completed dosing of eight subjects in an August 2024 Phase 2 double-blind multiple-dose study. Eight subjects is a small group for a study at that stage. An open-label, multiple-dose study began dosing in December 2024. The drug has orphan designation from the FDA and the EMA, plus Fast Track and Rare Pediatric Disease designations from the FDA.

ARCT-032, for cystic fibrosis, started a Phase 2 multiple ascending dose study in December 2024. It is meant to find a safe and effective dose in patients with Class I, or null, CFTR mutations and others who do not benefit from CFTR modulators. An earlier Phase 1b study in New Zealand completed dosing and follow-up for seven participants in July 2024.

Arcturus also began a Phase 1 trial of a seasonal influenza self-amplifying mRNA vaccine with CSL Seqirus in January 2024. In December 2024 it started a Phase 1 trial of a pandemic avian influenza vaccine funded by the U.S. Biomedical Advanced Research and Development Authority. The business section gives no start date or enrollment for later-stage work on those vaccines.

The business section does not state cash, debt or losses, and the late notice does not give them either.

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