Arcturus Therapeutics Holdings Inc

We are a messenger RNA medicines company focused on the development of liver and respiratory rare disease therapeutics. We have ongoing Phase 2 clinical studies for our RNA therapeutic candidates to potentially treat ornithine transcarbamylase (OTC) deficiency and cystic fibrosis (CF).

We developed the world’s first approved self-amplifying messenger RNA (sa-mRNA) vaccine, KOSTAIVE ("KOSTAIVE"), which we have partnered with Seqirus, Inc. ("CSL Seqirus"), a part of CSL Limited. KOSTAIVE has achieved approval in Japan, the European Union and the United Kingdom as a vaccine against COVID-19, and sales of KOSTAIVE began in Japan in October 2024.

We have several key platform technologies that we leverage to develop and advance a pipeline of mRNA-based therapeutics for rare genetic disorders with significant unmet medical needs and vaccines for infectious diseases. Current mRNA medicines have two critical components: the messenger RNA ("mRNA") constructs and the lipid nanoparticles ("LNP") which help deliver the mRNA to disease-relevant target tissues. We have extensive expertise in the design and optimization of mRNA constructs, including with respect to a type of mRNA technology known as self-amplifying mRNA (sa-mRNA). Our proprietary self-amplifying mRNA technology platform, or STARR ("STARR"), has been demonstrated to induce a robust, longer-lasting and broader humoral immune response at lower dose levels than conventional mRNA-based vaccines. Our proprietary LNP delivery system, LUNAR ("LUNAR"), is intended to address the major hurdle in RNA drug development, namely the effective and safe delivery of RNA to disease-relevant target tissues. LUNAR may enable multiple nucleic acid medicines. We also have significant expertise and valuable know-how in the development and scalability of complex and robust manufacturing processes required to deliver the next generation of nucleic acid medicines.

Our internal pipeline includes RNA therapeutic candidates to potentially treat ornithine transcarbamylase (OTC) deficiency and cystic fibrosis (CF), both rare diseases. In our vaccine program, we have partnered with CSL Seqirus, one of the world’s leading influenza vaccine providers, on the development and commercialization of mRNA vaccines for COVID-19, influenza and three other infectious diseases. In CSL Limited’s half-year results presented on February 11, 2026, CSL Limited reported an accounting write-down of approximately $430 million attributable to our collaboration agreement with CSL Seqirus, citing declining COVID-19 disease burden and more onerous U.S. regulatory requirements.