Regenxbio said the FDA has placed a clinical hold on its Hunter syndrome therapy after the discovery of unusual spine MRI findings in five participants in a study.
- The clinical hold pauses a study and prevents new or existing patients from receiving the experimental drug.
- The patients showed no related symptoms and continued to demonstrate stable or improved behavioral results.
- Investigators classified the findings as non-serious, while radiologists believe they are likely benign.
Shares of Regenxbio (RGNX) plunged nearly 22% in pre-market trading on Monday after the biotech firm announced a regulatory setback related to its experimental RGX-121 gene therapy for Hunter syndrome.
RGNX stock is on track for a third straight session of losses and is currently trading at over 2-month lows.
What Happened?
On Monday, the company announced that the U.S. Food and Drug Administration (FDA) placed a clinical hold on RGX-121, which is being developed for Hunter syndrome, a rare inherited disorder that causes sugar molecules to build up inside cells, damaging physical and mental development.
An FDA clinical hold pauses a study, prevents new patients from receiving the experimental drug, and may require existing participants to also stop receiving the treatment.
Why Did The FDA Place A Clinical Hold?
The FDA’s decision followed the discovery of unusual spine MRI findings in five participants in the Campsiite study. The study has a total of 13 participants. The patients received RGX-121 through injections into fluid-filled areas around the brain roughly three to six years ago. The findings included either a small nodule or a small cyst-like mass.
All five patients showed no related symptoms and continued to demonstrate stable or improved neurocognitive and behavioral results.
Investigators classified the findings as non-serious, while radiologists believe they are likely benign. However, there is currently no clinical or pathological evidence to confirm their cause or exact nature, and no nodules or masses are found on brain scans.
What’s Next?
The setback comes shortly after Regenxbio said a July meeting with the FDA had reaffirmed a path forward for RGX-121, with the company targeting a third-quarter resubmission of its marketing application. It no longer expects to resubmit the application in the near term.
Regenxbio and partner NS Pharma are reviewing additional scans and longer-term follow-up data. The companies will determine their next steps after receiving the FDA’s complete clinical-hold letter.
“We remain focused on our Duchenne and retinal disease candidates, which utilize a different capsid and routes of administration, with near-term catalysts that are on track, including the planned submission of the Duchenne BLA this quarter and the wet AMD topline pivotal data announcement in the fourth quarter,” said Curran Simpson, CEO of Regenxbio.
Earlier this month, the company said its existing cash, a $100 million milestone payment and around $107.8 million in net offering proceeds should fund operations into the fourth quarter (Q4) of 2027.
Retail Calls Selloff An Overreaction
Despite the sharp decline, retail sentiment for RGNX on Stocktwits flipped ‘bullish’ from ‘bearish’ over the past 24 hours.
One user said the stock is “still a very good long position”
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Another user called the selloff an overreaction.
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The stock has been under strong selling pressure so far this year, declining more than 42%.
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