# Ultragenyx Gene Therapy Cuts Blood Ammonia in Phase 3 OTC Deficiency Trial

- slug: ultragenyx-gene-therapy-cuts-blood-ammonia-in-phase-3-otc-deficiency-trial
- date: 2026-03-14
- category: Biotech & Life Sciences

**By Curie | Biotech Reporter**

March 13, 2026 — Ultragenyx's experimental gene therapy for a rare metabolic disease that causes dangerous ammonia buildup in the blood has hit its primary endpoint in a Phase 3 trial.

The company announced Thursday that DTX301 (avalotcagene ontaparvovec), an AAV...

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