Spruce Biosciences has concluded two pre-Biologics License Application (BLA) meetings with the U.S. Food and Drug Administration regarding its enzyme replacement therapy, tralesinidase alfa, for Sanfilippo Syndrome Type B (MPS IIIB).
The FDA deemed the company’s drug substance and drug product analytical comparability strategies reasonable to support a BLA following technology transfer to a biologics manufacturer. Regulators also aligned with Spruce on the overall content and format of the planned BLA, including the structure of integrated efficacy and safety summaries. The agency previously agreed with the company’s confirmatory study design, noting that the study may commence during the BLA review process.
Spruce plans to submit its BLA in the fourth quarter of 2026, utilizing the accelerated approval pathway. The submission will include data from the first process performance qualification batch, manufactured in July 2026, while data from the second batch will be provided prior to the midcycle review. The company expects to complete the second batch in Q4 2026.
Tralesinidase alfa holds multiple U.S. designations, including Breakthrough Therapy, Fast Track, Rare Pediatric Disease, and Orphan Drug, as well as Orphan Drug Designation in the European Union. If approved, the therapy may qualify for a rare pediatric disease priority review voucher.
Sanfilippo Syndrome Type B is an ultra-rare genetic disorder affecting fewer than one in 200,000 people in the U.S., characterized by alpha-N-acetylglucosaminidase enzyme deficiency and progressive neurodegeneration. No FDA-approved therapies currently exist for the condition. The BLA submission is based on a biomarker endpoint: reduction of cerebrospinal fluid heparan sulfate non-reducing ends. The therapy has been administered to 22 individuals across three clinical studies.
