Business
REGENXBIO Announces Regulatory Update on Ultra Rare MPS Programs
REGENXBIO Inc. (Nasdaq: RGNX) today announced that the U.S. Food and Drug Administration (FDA) placed a clinical hold on its investigational gene therapy, RGX-111, for the treatment of MPS I, also known as Hurler syndrome, following preliminary analysis of a single case of neoplasm (intraventricular CNS tumor) in a participant treated in its Phase I/II study. The FDA also placed a clinical hold on RGX-121, for the treatment of MPS II, also known as Hunter Syndrome, citing the similarities in pro
About this update from Regenxbio Inc.
[{"type":"text","content":"ROCKVILLE, Md., Jan. 28, 2026 /PRNewswire/ -- REGENXBIO Inc. (Nasdaq: RGNX) today announced that the U.S. Food and Drug Administration (FDA) placed a clinical hold on its investigational gene therapy, RGX-111, for the treatment of MPS I, also known as Hurler syndrome, following preliminary analysis of a single case of neoplasm (intraventricular CNS tumor) in a participant treated in its Phase I/II study. The FDA also placed a clinical hold on RGX-121, for the treatment of MPS II, also known as Hunter Syndrome, citing the similarities in products, study populations, and shared risk between the clinical studies.","length":622,"tagName":"p"},{"type":"text","content":"The case was identified during a routine brain MRI of an asymptomatic five-year-old participant who received intracisternal RGX-111 four years prior. Preliminary genetic analysis of the resected tumor detected an AAV vector genome integration event associated with overexpression of a proto-oncogene (PLAG1), which is known to be susceptible to chromosomal rearrangements. The investigation to determine if this SAE is drug related is ongoing. The causality has not been established. The participant continues to be asymptomatic, with positive developmental advancements noted by the treating physician. No evidence of neoplasm has been reported in the nine other participants treated with RGX-111 nor in the 32 participants treated with RGX-121.","length":746,"tagName":"p"},{"type":"text","content":""We are surprised by FDA's decision to place our RGX-121 program on hold while the investigation of this single, inconclusive incident in RGX-111 continues," said Curran Simpson, President and CEO of REGENXBIO. "These are separate therapies, and the positive safety profile of RGX-121 in more than 30 patients treated, including those dosed nearly seven years ago, remains unchanged. Patient safety is our top priority, and we, our investigators, and the patient community remain confident in the benefit-risk ratio of RGX-121 and are highly encouraged by the meaningful efficacy profile demonstrated in the pivotal trial. RGX-121 presents an opportunity to address the urgent, significant unmet medical need in this ultra-rare disease community, and continued delay means continued neurodevelopmental decline in boys with MPS II."","length":855,"tagName":"p"},{"typ...