San Diego‑based Arcturus Therapeutics Holdings Inc. released data from its Phase 2 study of ARCT-810, an investigational mRNA therapy for ornithine transcarbamylase (OTC) deficiency. The trial, which enrolled participants aged 12 and older, reported that the drug was generally safe and well tolerated. First‑morning fasting ammonia levels remained within the normal range, even when participants increased protein intake. At the 0.5 mg/kg dose, mean glutamine concentrations also fell into the normal range, and all subjects experienced weight gain.
The company also disclosed performance metrics for its next‑generation LUNAR 2.0 mRNA delivery platform. Non‑human primate studies showed a 40‑fold increase in human erythropoietin expression compared with the earlier LUNAR 1.0 system, and a 38‑fold potency advantage over the ATX‑95 lipid in producing human OTC enzyme.
OTC deficiency, the most common urea‑cycle disorder, affects roughly 10,000 individuals in Europe and the United States. Current management relies on a low‑protein diet and nitrogen‑scavenging drugs, which do not address the underlying enzyme deficiency.
Following feedback from an FDA Type C meeting in June, Arcturus will amend the ongoing ARCT‑810 Phase 2 protocol to incorporate ARCT‑2601, a therapy built on the LUNAR 2.0 platform. Dosing of ARCT‑2601 is planned for near year‑end.
In parallel, the company announced that its acquisition of myNEO, an AI‑driven drug‑discovery firm, is expected to close in October, subject to customary conditions.
Arcturus shares closed at $13.30, down $1.08 (‑7.51%). In after‑hours trading the stock rose to $14.00, up $0.70 (+5.26%).
