Arcturus Therapeutics Holdings Inc. announced it will host a virtual key opinion leader presentation of Phase 2 interim data for ARCT-810, an investigational mRNA therapeutic for ornithine transcarbamylase (OTC) deficiency, on Monday, June 30, 2025, at 12:00 p.m. ET. The San Diego-based commercial mRNA medicines company will release a press release summarizing the data at 11 a.m. ET prior to the presentation.
Phase 2 Trial Results to Be Discussed
The presentation will review interim clinical data from ARCT-810 Phase 2 trials evaluating the safety and pharmacodynamics of multiple doses in adolescent and adult participants with OTC deficiency. The data represents a significant milestone for the investigational therapy designed to address the most common urea cycle disorder.
Expert Panel Features Leading Authorities
Two internationally recognized experts will participate alongside Arcturus management:
Dr. Marshall Summar, CEO at Uncommon Cures and formerly Chief of the Division of Genetics and Metabolism at Children's National Hospital, brings over four decades of clinical and research leadership in urea cycle disorders. Dr. Summar is a founding member and Executive Committee member of the NIH UCD Consortium and has authored over 40 UCD-related publications. He received the NORD Lifetime Achievement Award in 2022 for his contributions to rare disease research.
Dr. Johannes Häberle, Professor and Director of the Metabolic Laboratory at the University of Zurich, serves as a globally recognized expert in pediatric metabolic medicine. With over 200 publications and 10,000+ citations, Dr. Häberle chaired the European working group that developed the 2019 UCD diagnosis and treatment guidelines and received the prestigious Archibald Garrod Award in 2019.
Understanding OTC Deficiency
Ornithine transcarbamylase deficiency represents the most common urea cycle disorder, affecting inherited metabolic processes in the liver that remove toxic waste products during protein digestion. Caused by mutations in the X-linked OTC gene, the condition leads to a non-functional or deficient OTC enzyme and typically affects males more severely.
The OTC enzyme catalyzes the critical metabolic process converting toxic ammonia to urea for kidney excretion. In patients with OTC deficiency, this conversion fails, leading to high blood ammonia levels that can cause seizures, progressive neurocognitive impairment, coma, and death. The condition also results in increased blood glutamine concentrations with low to normal citrulline levels and elevated urine orotic acid.
Severe cases typically present early in life, while patients with milder symptoms may receive diagnoses as adolescents or adults. Approximately 10,000 people in Europe and the U.S. have OTC deficiency.
Current Treatment Limitations
No cure exists for OTC deficiency apart from liver transplantation, which carries significant surgical risks, potential organ rejection, and requires lifelong immunosuppressant therapy. Current standard care involves a challenging-to-maintain low-protein diet, essential amino acid substitution, and nitrogen scavenging medications that prevent acutely toxic ammonia levels but may not prevent chronic neurotoxic effects. These treatments fail to address the underlying disease cause.
ARCT-810 Therapeutic Approach
ARCT-810 represents an intravenously administered investigational mRNA therapeutic designed to express normal functional OTC enzyme in the liver of individuals with OTC deficiency. The therapy aims to restore normal functional OTC enzyme, potentially improving urea cycle activity, reducing abnormally elevated glutamine, maintaining normal ammonia levels, and eliminating future metabolic crisis risks.
The therapeutic utilizes Arcturus' mRNA design construct and proprietary manufacturing process, incorporating the company's extensive lipid library and LUNAR® delivery platform to deliver OTC mRNA to hepatocytes.
Regulatory Recognition
ARCT-810 has received significant regulatory support, including Orphan Medicinal Product Designation and an approved pediatric investigation plan from the European Medicines Agency. The U.S. Food and Drug Administration has granted Orphan Drug Designation, Fast Track Designation, and Rare Pediatric Disease Designation for OTC deficiency treatment.
Company Background
Founded in 2013, Arcturus Therapeutics operates as a commercial mRNA medicines and vaccines company with three enabling technologies: LUNAR® lipid-mediated delivery, STARR® mRNA technology, and mRNA manufacturing expertise. The company developed KOSTAIVE®, the first self-amplifying messenger RNA COVID vaccine approved globally, and maintains collaborations with CSL Seqirus and a joint venture in Japan called ARCALIS.
Arcturus' pipeline includes RNA therapeutic candidates for OTC deficiency and cystic fibrosis, alongside partnered mRNA vaccine programs for COVID-19 and influenza. The company's technologies are protected by over 500 patents and patent applications across the U.S., Europe, Japan, China, and other countries.
