The FDA has agreed to reconsider a previously rejected gene therapy for Hunter syndrome developed by Regenxbio, signaling a shift toward greater flexibility in how rare-disease treatments are evaluated, The Wall Street Journal reports.
The therapy, designed for a very small patient population, was initially turned down because regulators raised concerns about the clinical trial design, including the absence of a placebo-controlled study and limited patient numbers.
The treatment was tested in roughly a dozen patients, all of whom received the therapy rather than being split into treatment and control groups. This made it difficult for regulators to compare outcomes against an untreated baseline. Despite these limitations, the company has continued to collect long-term follow-up data showing potential clinical benefits in treated patients.
Under the revised approach, the FDA is now open to reviewing the existing dataset rather than requiring a new randomized trial or additional patient enrollment. This is significant because ultra-rare diseases often make large, traditional trials impractical or ethically challenging, given how few patients exist worldwide.
The change does not guarantee approval, but it gives the developer a clearer path to resubmit the application under expedited review. It also reflects a broader trend in which regulators are reassessing evidentiary standards for gene therapies targeting extremely rare conditions, balancing scientific rigor with the realities of small patient populations.
The Wall Street Journal has the full story.
