The FDA has rejected Regenxbio’s biologics license application for RGX-121, an experimental gene therapy for Hunter syndrome.
In a complete response letter issued Feb. 7, the FDA cited concerns about trial eligibility criteria, the comparability of control groups and the use of a surrogate endpoint. The agency said the submitted data did not provide substantial evidence of effectiveness to support approval under the accelerated pathway, which the drug was accepted for in May, according to a Feb. 9 news release.
The decision follows a clinical hold the FDA placed Jan. 28 on two Regenxbio gene therapy programs — RGX-111 and RGX-121 — after a brain tumor was detected in a child who had received RGX-111 four years earlier. Although the tumor’s etiology is unknown and RGX-121 has shown a favorable safety profile in more than 30 patients, the FDA extended the hold to both programs pending further investigation, according to the release.
Regenxbio said it plans to request a Type A meeting with the agency to discuss a path forward, including resubmission of the BLA and additional long-term clinical data.
