Ultragenyx reported that its gene therapy candidate met a primary (and in one report, a co‑primary) endpoint in a phase III study for an inherited urea cycle disorder, demonstrating a statistically significant reduction in blood ammonia levels. The trial enrolled patients with ornithine transcarbamylase (OTC) deficiency and the readout covers metabolic control endpoints commonly used in regulatory assessments for urea cycle disorders. The result positions Ultragenyx to advance regulatory discussions and potential filings for a therapy addressing a high‑unmet‑need rare metabolic disease. Company statements and the study’s topline data will be critical to defining the path to approval, commercial planning and manufacturing scale for a systemic gene therapy.