July 6, 2026 —
The U.S. Food and Drug Administration has cleared an Investigational New Drug application for an investigational AAV9/SUMF1 gene therapy for multiple sulfatase deficiency, or MSD, enabling a planned first-in-human clinical study in children with the ultra-rare lysosomal storage disorder.
The IND is sponsored by the National Center for Advancing Translational Sciences, or NCATS, part of the National Institutes of Health. The program was developed through the Accelerating Medicines Partnership Bespoke Gene Therapy Consortium, or AMP BGTC, a public-private partnership involving the NIH, FDA, biopharmaceutical companies, and nonprofit organizations.
MSD is a life-limiting pediatric disorder caused by loss-of-function mutations in the SUMF1 gene. SUMF1 encodes an enzyme required to activate the family of sulfatase enzymes. When SUMF1 is deficient, sulfatase activity is impaired, leading to accumulation of sulfated substrates in cells and progressive neurologic and systemic decline.
The disease affects growth, development, neurological function, and multiple organ systems. MSD has an average life expectancy of approximately 13 years, and there are currently no disease-modifying treatments. Care is limited to supportive management aimed at symptoms and quality of life.
The investigational therapy uses an AAV9 vector to deliver a functional copy of SUMF1, with the goal of restoring production of the enzyme needed to activate sulfatases throughout the body. The approach is designed to address the underlying genetic cause of MSD rather than only managing downstream symptoms.
Preclinical studies conducted at The Jackson Laboratory and UT Southwestern Medical Center supported the IND application. In Sumf1 knockout mouse models, AAV9/SUMF1 delivery extended survival and mitigated disease features. Neonatal treatment supported survival out to one year, while later administration through the cerebrospinal fluid at day seven of life also improved outcomes.
The planned first-in-human study will primarily assess safety and tolerability, with potential therapeutic effects evaluated as a secondary objective. Public details on dosing, route of administration, enrollment criteria, and specific endpoints have not yet been disclosed. The clinical study will be led by principal investigators Laura Adang, MD, PhD, and Rebecca Ahrens-Nicklas, MD, PhD, of Children’s Hospital of Philadelphia.
The program also reflects the broader goal of the AMP BGTC: to create a more standardized development pathway for bespoke gene therapies targeting ultra-rare diseases. MSD entered the consortium after much of its preclinical work had already been completed, and BGTC supported clinical-grade vector manufacturing, protocol development, and the IND submission process.
While IND clearance is an important regulatory milestone, it does not establish clinical safety or efficacy. AAV9 gene therapies can carry known risks, including immune responses and potential organ toxicity, making the initial study’s focus on safety and tolerability especially important.
For MSD families, the IND clearance marks a step toward the first human testing of a disease-targeted genetic medicine. If the program advances successfully, it could provide a model for translating AAV-based therapies for other devastating ultra-rare pediatric disorders with limited commercial development pathways.
