FDA places second clinical hold on Regenxbio’s Hunter syndrome gene therapy after spinal masses detected

The FDA issued another clinical hold on Regenxbio’s RGX-121 gene therapy for Hunter syndrome after investigators found spinal masses in five trial participants.

The masses, observed on MRI scans, were described as likely benign and the affected patients showed no symptoms, maintaining stable or improving neurocognitive and neurobehavioral scores.

This hold follows an earlier pause in January and a subsequent FDA rejection of Regenxbio’s application, prompting the company to abandon plans for a near-term resubmission.

Regenxbio disclosed that the share price dropped more than 25% in early trading on Monday, reflecting investor concern over the regulatory setbacks.