Arcturus Therapeutics Holdings Inc. Announces Positive Interim Phase 2 Multiple Dose Data for Ornithine Transcarbamylase Deficiency Program

Published: 2025-06-30 14:35:30 ET ARCT

Published on 06/30/2025 at 14:35

Arcturus Therapeutics Holdings Inc. announced positive Phase 2 interim results in people with OTC deficiency treated with ARCT-810, an mRNA therapeutic candidate designed to replace the OTC enzyme and restore urea cycle activity preventing hyperammonemia crises. Along with the observation of stable ammonia levels in all patients during treatment, these data add a level of robustness to this new interim dataset. The combined biomarker data is unprecedented for an mRNA therapeutic therapeutic and, importantly, provides a potentially accelerated path forward to a multi-biomarkerdriven pivotal study.

Multiple dosing data are available from two Phase 2 studies; a completed placebo-controlled study in Europe that randomized six participants to ARCT-810 doses and an open-label multiple ascending dose study with interim data from the initial three completed participants. The ongoing U.S. Phase 2 open-label study uses a modified and improved 15N-ureagenesis assay (Allegri et al., 2025). The assay measures relative ureagenesis function (RUF) against a normal range established from healthy controls (N = 29).

ARCT-810 is an intravenously administered investigational mRNA therapeutic designed to express normal functional OTC enzyme in the liver of individuals with OTC deficiency. ARCT-810 has received Orphan Medicinal Product Designation and an approved pediatric investigation plan (PIP) from the European Medicines Agency (EMA), and Orphan Drug Designation, Fast Track Designation along with Rare Pediatric Disease Designation from the U.S. Food and Drug Administration (FDA) for the treatment of OTC deficiency. OTC is a key enzyme in the urea cycle which converts toxic ammonia into urea.