Arcturus Therapeutics Holdings Inc.

Company overview

Arcturus Therapeutics Holdings Inc. develops messenger RNA (mRNA) medicines focused on liver and respiratory rare diseases and on vaccines for infectious diseases. Its core platforms are LUNAR lipid-mediated delivery (LNP) and STARR self-amplifying mRNA (sa-mRNA). The company also maintains manufacturing and formulation capabilities for mRNA medicines.

Key internal programs include LUNAR-OTC (ARCT-810) for OTC deficiency and LUNAR-CF (ARCT-032) for cystic fibrosis. The vaccine program uses STARR-LUNAR for infectious diseases (KOSTAIVE, ARCT-154, and related variants) in collaboration with CSL Seqirus.

Selected pipeline and programs

• OTC deficiency

  • ARCT-810 (LUNAR-OTC): Phase 2 program ongoing. A U.S. Phase 2 open-label study started December 2024. An EU/UK Phase 2 cohort completed dosing (eight participants) in mid-2025. Reported Phase 2 data show decreases in glutamine and improvements in ureagenesis (RUF). A Type C FDA meeting is planned for H1 2026 to discuss future pediatric studies under the Rare Disease Evidence Principles (RDEP).

• Cystic fibrosis (CF)

  • ARCT-032 (LUNAR-CF): Lead CF candidate in a Phase 2 multiple-dosing study that began December 2024. Interim results in October 2025 showed mucus burden reductions by HRCT in 4 of 6 Class I CF adults. The candidate was generally safe and well tolerated. A 12-week safety and preliminary efficacy cohort is planned to start in 2026 after a third cohort completes treatment.

• COVID-19 and influenza vaccines

  • KOSTAIVE (ARCT-154): sa-mRNA COVID-19 vaccine licensed as KOSTAIVE in Japan and Europe. Commercial sales began in Japan in October 2024 with Meiji as partner. European Commission marketing authorization was granted in February 2025; United Kingdom authorization followed in January 2026. A BLA submission in the U.S. was delayed after the FDA requested additional data for a single-dose indication and for regulatory framework alignment as of October 2025. Variants and updated presentations, including those targeting Omicron subvariants, have been approved or marketed in various regions. Meiji was added as a manufacturing site for ARCT-154.

• Seasonal influenza and BARDA-supported programs

  • LUNAR-FLU: Influenza vaccine development in collaboration with CSL Seqirus using LUNAR/STARR.
  • LUNAR-H5N1: BARDA-funded H5N1 pandemic influenza candidate in Phase 1 with Fast Track designation granted by FDA for ARCT-2304 (H5N1). BARDA supports development under a cost-reimbursement contract.

• Other discovery programs

  • Work includes LUNAR-I/O for immuno-oncology, cancer vaccine development, and exploratory discovery projects such as a post-exposure HPV therapeutic vaccine supported by a Gates Foundation grant.

Platform technologies and capabilities

• LUNAR: A lipid-mediated delivery platform with a library of more than 300 proprietary ATX lipids. Designed for biodegradability, targeted delivery, and scalable manufacturing. It uses neutral charge at physiological pH and endosomal escape triggered by pH changes to reduce toxicity risk.
• STARR: A self-amplifying mRNA platform that includes a replicase to increase and prolong antigen expression, enabling lower doses and stronger mucosal and immune responses when used with LUNAR.
• Manufacturing: In-house mRNA drug substance production and drug product formulation with LUNAR delivery, supported by multiple contract manufacturing partners and an in-house joint venture (ARCALIS, Japan) for MS/CMO capabilities. Ongoing optimization includes stability improvements, lyophilized formats, and supply chain resiliency.

Commercialization and collaborations

• CSL Seqirus (CSL Limited)

  • Global exclusive rights for research, development, manufacture, and commercialization of sa-mRNA vaccines for COVID-19, influenza, and three additional infectious diseases; non-exclusive rights in pandemic preparedness.
  • Financial terms include a $200 million up-front payment, potential development and commercial milestones, and profit/royalty sharing arrangements. Amendments to development plans and royalty terms occurred in 2024 and 2025. Arcturus initiated arbitration over a milestone payment related to EC marketing authorization (2025). CSL Limited reported a write-down of about $430 million in 2026 related to this collaboration.

• Cystic Fibrosis Foundation (CFF)

  • Funding and collaboration for LUNAR-CF development with royalty arrangements and potential disposition/licensing provisions.

• BARDA

  • Cost-reimbursement contract supporting the H5N1 program, covering up to $63.2 million in reimbursable costs; the contract is terminable by BARDA for convenience.

• ARCALIS / Japan manufacturing joint venture

  • ARCALIS, a joint venture with Axcelead (Japan), focuses on mRNA manufacturing. Meiji Seika Pharma was added as a manufacturing site for KOSTAIVE (ARCT-154) in Japan. Domestic manufacturing sites received approvals in 2025 and onshore manufacturing approvals followed in 2026.

• Other relationships

  • Gates Foundation grant (2024–2025) for a therapeutic HPV vaccine candidate discovery and additional partnerships and contracts with government and private entities.

Financial highlights

• Employees: Approximately 111 employees as of December 31, 2025 (106 full-time, 5 part-time), supplemented by contractors and scientific consultants.
• Cash and equivalents: $230.9 million as of December 31, 2025.
• Accumulated deficit: $514.6 million as of December 31, 2025.
• 2025 revenue: Reported as arising from non-recurring milestone payments and license revenue under the CSL Seqirus collaboration.
• Public equity financing: A controlled equity offering program (Sales Agreement) established with Cantor/Wells Fargo/Williams Capital for up to $200 million. About $12 million gross proceeds were raised under the agreement (1,179,201 shares sold) with remaining capacity under the facility.
• Legal and regulatory: Ongoing litigation and arbitration, including matters involving AbbVie and Capstan Therapeutics and arbitration with CSL Seqirus related to milestone payments. Regulatory approvals and updates for KOSTAIVE across Japan, EU, UK, and U.S. timing considerations are active.

Corporate and operations

• Headquarters: San Diego, California.
• Properties:
  • 10285 Science Center Drive: Approximately 43,234 sq ft, leased through September 2032.
  • 10628 Science Center Drive, Suite 250: Approximately 24,700 sq ft of office and lab space, vacated in December 2025; leased through March 2027.
• Intellectual property: More than 500 patents and pending applications as of January 31, 2026, covering the LUNAR and STARR platforms, delivery technologies, and therapeutic candidates (OTC, CF, COVID-19, influenza). Patent expirations are estimated in the 2028–2046 range, subject to extensions.

Business focus summary

Arcturus develops and commercializes RNA medicines and vaccines using its proprietary LUNAR delivery and STARR sa-mRNA platforms. Near-term clinical priorities are ARCT-810 (LUNAR-OTC) for OTC deficiency and ARCT-032 (LUNAR-CF) for cystic fibrosis. The principal near-term commercial product is KOSTAIVE (ARCT-154) for COVID-19 in collaboration with CSL Seqirus, with commercialization underway in Japan and Europe and ongoing regulatory activity in the U.S., UK, and EU. The pipeline also includes influenza vaccines (LUNAR-FLU with CSL Seqirus), a BARDA-supported H5N1 candidate, and exploratory oncology and discovery programs.