Ultragenyx Gene Therapy DTX301 Hits Key Endpoint in Phase 3 Trial for Ornithine Transcarbamylase Deficiency

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Ultragenyx's DTX301 gene therapy achieved an 18% reduction in 24-hour plasma ammonia levels compared to placebo at Week 36, meeting one of two co-primary endpoints12

The Phase 3 Enh3ance study enrolled 37 patients across 10 countries and 16 sites, randomized between DTX301 (18 patients) and placebo (19 patients)2

Eight of nine patients with abnormal ammonia levels at baseline reached and maintained normal levels after DTX301 treatment23

DTX301-treated patients reduced ammonia scavenger medications by a mean of 27% and increased protein intake by approximately 13% while maintaining normal ammonia levels24

Patient-reported outcomes showed 71% of treated patients rated much improved for OTC symptoms on the patient global impression scale at Week 24, compared with 0% on placebo4

The trial's second co-primary endpoint—assessing the percentage of patients achieving response through discontinuation or reduction in baseline disease management—will be assessed at 64 weeks, with data expected in the first half of 20271

Safety profile showed mostly mild to moderate hepatic reactions managed with steroids; five hyperammonemic crises occurred in the placebo group (one fatal) versus one in the treated group (non-fatal)12

Sources:

1. https://www.fiercebiotech.com/biotech/ultragenyx-gene-therapy-lessens-ammonia-levels-ph-3-rare-disease-win

2. https://www.investing.com/news/company-news/ultragenyx-reports-positive-phase-3-data-for-otc-gene-therapy-93CH-4557032

3. https://www.gurufocus.com/news/8701899/ultragenyx-rare-sees-positive-phase-3-results-for-gene-therapy

4. https://www.stocktitan.net/sec-filings/RARE/8-k-ultragenyx-pharmaceutical-inc-reports-material-event-826abefc96ad.html