# Gene Therapy for Hunter Syndrome Hits Regulatory Wall: What the RGX-121 Rejection Means for Rare Disease Treatments

- slug: gene-therapy-for-hunter-syndrome-hits-regulatory-wall-what-the-rgx-121-rejection-means-for-rare
- date: 2026-03-16
- category: Biotech & Life Sciences

**Regenxbio's RGX-121 showed remarkable biomarker reduction in clinical trials, but the FDA isn't convinced that's enough**

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In November 2025, a three-year-old boy named Ollie made headlines when doctors at Manchester Children's Hospital described his response to an experimental gene therapy...

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