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Getting the latest healthcare news for you
The FDA has placed a clinical hold on RGX-121 (clemidsogene lanparvovec), a gene therapy for Hunter syndrome (MPS II), after spinal MRI abnormalities were found in 5 trial participants. REGENXBIO says the findings appear benign and patients remain asymptomatic, but the cause is still unknown. A near-term BLA resubmission is now off the table.
The FDA has placed a clinical hold on RGX-121 (clemidsogene lanparvovec), REGENXBIO's investigational one-time gene therapy for mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome. The hold was triggered after spinal MRI abnormalities — small nodules or cystic masses — were detected in 5 participants from the CAMPSIITE pivotal trial who had received the therapy via intracisternal or intraventricular administration roughly 3 to 6 years earlier.
The findings were classified as nonserious and likely benign by reviewing radiologists, and all 5 affected participants remain asymptomatic, with stable or improving neurocognitive assessments. Still, the cause and clinical significance remain undetermined, and REGENXBIO has confirmed it does not expect to resubmit a biologics license application (BLA) in the near term. The company and partner NS Pharma are continuing to gather imaging and longer-term follow-up data, pending FDA feedback.
Key Takeaways:
Why it matters: Hunter syndrome is a rare, progressive X-linked disorder with no approved therapy that crosses the blood-brain barrier. RGX-121 had been seen as a potential breakthrough for the neurological manifestations of the disease. This latest hold adds another significant setback for patients and families awaiting a one-time treatment option.
