REGENXBIO announced on June 22 that it will resubmit its application for approval of its Hunter syndrome gene therapy, RGX-121, in the third quarter following a recent shift in guidance from the U.S. Food and Drug Administration.
The company previously received a complete response letter from the FDA in February, which cited concerns about eligibility criteria used in REGENXBIO’s registrational study and reliance on external controls that the agency said "lack the comparability" with trial participants. The FDA had recommended using an appropriate untreated control group.
According to REGENXBIO, the agency has now acknowledged that existing clinical data for NAVSUNLI (RGX-121) is sufficient for consideration under the accelerated approval pathway and does not require enrolling additional patients or conducting new studies, including an untreated control arm. The FDA requested that REGENXBIO schedule a Type A meeting to review longer-term biomarker and clinical data before submitting a new biologics license application. The agency indicated it would review any resubmission on an expedited basis, with labeling discussions beginning soon after.
REGENXBIO expects this meeting to take place in July. Chief Executive Officer Curran Simpson said in a prepared statement, “We are encouraged by recent signals from the new FDA leadership reinforcing a commitment to address the unique nature of rare diseases and use the accelerated approval pathway to bring transformative therapies to patients with serious, unmet medical needs.” Simpson added that REGENXBIO will continue working closely with regulators and remains focused on bringing RGX-121 to boys living with Hunter syndrome as quickly as possible.
The company’s planned resubmission is expected alongside uniQure’s first submission for its Huntington’s disease gene therapy later this year after similar changes in FDA requirements regarding trial design. These developments come amid broader signs of increased flexibility at the agency toward rare disease therapies under acting commissioner Kyle Diamantas.
