Summary of Arcturus Therapeutics KOL Presentation on ARCT-810 Phase II Interim Data for OTC Deficiency Company Overview - **Company**: Arcturus Therapeutics - **Headquarters**: San Diego - **Focus**: mRNA medicines, specifically targeting rare liver diseases like ornithine transcarbamylase (OTC) deficiency [5][6] Industry Context - **Industry**: Biotechnology, specifically in the development of mRNA therapeutics for rare diseases - **Condition**: OTC deficiency is the most common urea cycle disorder with significant unmet medical needs [6][7] Key Points from the Presentation 1. **ARCT-810 Overview**: - ARCT-810 is an mRNA therapeutic designed to replace dysfunctional OTC enzymes, improving urea cycle activity, detoxifying ammonia, and potentially eliminating the need for liver transplants [6][7][8] - It utilizes Arcturus' proprietary lunar delivery platform for effective delivery to hepatocytes [7] 2. **Regulatory Designations**: - ARCT-810 has received multiple designations: orphan drug designation, orphan medicinal product designation, fast track designation, and rare pediatric disease designation [8] 3. **Phase II Study Design**: - Two Phase II studies were conducted: one in the US and one in Europe, focusing on safety, tolerability, and biomarker assessments [11][12] - The US study enrolled patients with more severe disease, while the European study included patients with stable disease [12] 4. **Biomarker Results**: - **Plasma Glutamine**: - In the European study, mean glutamine levels decreased from high to normal during treatment and began to rise again after four weeks post-treatment [13][14] - In the US study, glutamine levels normalized after three doses and remained normal for approximately twenty days [14] - **Ureagenesis Function**: - The new N15 assay showed significant increases in relative ureagenesis function (RUF) post-treatment, with a mean increase of 14.7% [16][17] - Two subjects achieved RUF levels above 50%, indicating clinically meaningful improvements [17] - **Ammonia Levels**: - Ammonia levels remained stable and within normal ranges after treatment, supporting the favorable glutamine and ureagenesis data [18] 5. **Safety Profile**: - The safety database included 40 participants, indicating that ARCT-810 was generally safe and well-tolerated [19] - No serious infusion-related reactions were reported, and adverse events were manageable [19][20] 6. **Next Steps**: - Arcturus plans to complete the ongoing Phase II US study and engage with regulatory agencies for a multi-biomarker driven pivotal trial [68][69] Additional Insights - **Clinical Implications**: - The KOLs emphasized the importance of normalizing diet and reducing the need for ammonia scavengers as key success metrics for OTC therapies [78][80] - mRNA therapies are viewed as a potential alternative to liver transplants, especially for severe cases [100][101] - **Comparison with Other Therapies**: - ARCT-810 is positioned as a more effective solution compared to existing ammonia scavengers, which do not restore urea cycle function [87][88] Conclusion - The interim data for ARCT-810 demonstrates promising results in reducing glutamine levels and improving urea cycle function, with a favorable safety profile. The company is poised to advance its clinical development and regulatory strategy to address the significant unmet needs in OTC deficiency treatment [67][68]