Key Highlights
- Shares of Regenxbio plummeted 25% to $8.05 following FDA’s decision to halt clinical trials for RGX-121
- The regulatory action followed detection of asymptomatic nodules or cystic formations on spinal imaging in five trial participants
- Medical experts classified the abnormalities as non-serious and probably benign, yet the FDA proceeded with the hold
- The company has withdrawn its near-term plans to resubmit the Biologics License Application for RGX-121
- Regenxbio maintains its schedule to file a BLA for its Duchenne therapy this quarter and unveil wet AMD results in the fourth quarter
Shares of Regenxbio experienced a sharp 25% decline to $8.05 on Monday following the FDA’s decision to implement a clinical hold on RGX-121, the company’s experimental gene therapy designed to treat Hunter syndrome. The stock experienced a temporary trading suspension before the announcement.
The regulatory suspension followed an enhanced MRI surveillance initiative that identified asymptomatic abnormalities in five trial participants. Each individual presented with a small nodular formation or cystic structure along their spinal column. All five subjects had been administered RGX-121 approximately three to six years prior to the discovery.
Medical investigators determined the discoveries to be non-serious in nature. Radiology specialists evaluated them as potentially benign, with no clinical or pathological confirmation establishing a direct connection to the therapeutic intervention.
Despite these assessments, the FDA proceeded with implementing a clinical hold on the trial program, leading Regenxbio to announce it no longer anticipates resubmitting its Biologics License Application for RGX-121 in the immediate future.
Just this past June, the FDA had informed Regenxbio that no supplementary studies would be required prior to resubmitting the BLA during the third quarter. That projected timeline has now been abandoned.
This marks the second time in recent months that a Regenxbio trial has been suspended by the FDA. RGX-111, another experimental treatment, was placed under clinical hold earlier this year, mere weeks ahead of a critical regulatory decision. The hold was subsequently applied to RGX-121 due to shared characteristics between the two therapeutic approaches.
Executive Commentary
Chief Executive Officer Curran Simpson characterized the discoveries as appearing “unique and limited” to the Hunter syndrome clinical program, while recognizing they “require longer-term follow-up and additional data analysis” before the organization can comprehensively evaluate RGX-121’s risk-benefit ratio.
All five affected patients continue demonstrating overall stability or positive progress in neurocognitive and neurobehavioral evaluations.
Hunter syndrome represents a rare inherited condition in which the body lacks the ability to metabolize complex carbohydrate molecules. The disorder predominantly impacts males and significantly limits life expectancy, with affected individuals typically living into their twenties.
Pipeline Progress Continues Elsewhere
Regenxbio reports that its Duchenne muscular dystrophy and wet age-related macular degeneration therapeutic programs utilize a distinct capsid technology and delivery methods and remain unaffected by the regulatory hold.
The organization intends to file a BLA for its Duchenne treatment candidate during the ongoing quarter.
Primary efficacy data for its wet AMD candidate, developed in collaboration with AbbVie, is anticipated in the fourth quarter. Financial analysts have identified this data release as a significant potential catalyst for Regenxbio’s stock performance.
Related biotechnology companies experienced spillover effects from the news. Sarepta Therapeutics declined 3.3% while EyePoint shares dropped 4.3% during Monday’s trading session.
Earlier in April, Barclays analyst Eliana Merle reduced Regenxbio’s rating to Equal Weight from Overweight, highlighting regulatory uncertainty and intensifying competition as potential headwinds for both development programs.
The company indicated it is collaborating with partner NS Pharma to review additional patient imaging data and long-term follow-up information, and will integrate FDA guidance into the strategic direction for RGX-121 moving forward.
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