Early Access Treatment With Tralesinidase Alfa in Mucopolysaccharidosis Type IIIB (Sanfilippo Syndrome Type B)

NCT07733856 | Unknown

• 1 other identifier: 250-502
• Study Type: expanded_access
• Target: N/A
• Locations: 0 countries
• Sites: N/A

Brief Summary

This is an intermediate-size patient population Early Access Program (EAP) providing access to intracerebroventricular (ICV) tralesinidase alfa (TA) for participants with mucopolysaccharidosis type IIIB (MPS IIIB, Sanfilippo Syndrome Type B). The primary objectives are to allow early access to TA treatment and to evaluate the safety and tolerability of TA ICV infusion. Approximately 10 participants will be enrolled at up to 3 US sites and treated with TA once weekly via ICV infusion for up to approximately 52 weeks, or until TA becomes commercially available.

Conditions

Mucopolysaccharidosis Type IIIB; MPS IIIB (Sanfilippo B Syndrome)

Keywords

Sanfilippo; MPS IIIB; Enzyme Replacement Therapy; NAGLU; Expanded Access; EAP

Interventions

Tralesinidase alfa (TA) DRUG

Tralesinidase alfa (TA) is a sterile solution of recombinant human alpha-N-acetylglucosaminidase fused with insulin-like growth factor 2 (rhNAGLU-IGF2), formulated at 30 mg/mL for ICV infusion. Dose: 200 mg (6.7 mL) for participants age ≥12 to \<24 months; 300 mg (10 mL) for participants age ≥24 months. Administered once weekly via ICV reservoir following isovolumetric removal of up to 10 mL CSF, infused over approximately 10 minutes. Stored frozen at -40°C (±10°C).

Eligibility Criteria

• Age: 12 Months+
• Sex: all
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)

You may qualify if:

• Has a diagnosis of MPS IIIB confirmed by deficient NAGLU enzyme activity analyzed at the laboratory during Screening.
• Is ≥12 and ≤60 months of age with a BSID-III-C raw score ≥70. or Is \>60 months of age regardless of cognitive level. Has provided written informed consent from a parent or legal guardian Has been determined by the investigator, after consultation with the participant (if applicable) and their family/caregiver, that the known risks of TA ICV infusion are outweighed by its potential benefits.
• If female and of childbearing potential, agrees to follow contraception guidelines from screening until 30 days after the last dose of TA.
• Has the ability to comply with program requirements, in the opinion of the investigator.

You may not qualify if:

• Has contraindications for neurosurgery (e.g., congenital heart disease, severe respiratory impairment, or clotting abnormalities).
• Has contraindications for MRI scans, if the investigator deems an MRI and not a CT scan is required for ICV access device placement or follow-up post-placement.
• Has a history of poorly controlled seizure disorder. Is prone to complications from ICV infusion, including participants with hydrocephalus or ventricular shunts.
• Has received any investigational medication within 30 days prior to the Baseline Visit or is scheduled to receive any investigational drug during the course of the program.
• Has a medical condition or extenuating circumstance that, in the opinion of the investigator, might compromise the participant's ability to comply with program requirements, the participant's well-being or safety, or the interpretability of the participant's clinical data.

Sponsors & Collaborators

• Spruce Biosciences: lead

MeSH Terms

Conditions

Mucopolysaccharidosis III

Condition Hierarchy (Ancestors)

Mucopolysaccharidoses; Carbohydrate Metabolism, Inborn Errors; Metabolism, Inborn Errors; Genetic Diseases, Inborn; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Lysosomal Storage Diseases; Mucinoses; Connective Tissue Diseases; Skin and Connective Tissue Diseases; Metabolic Diseases; Nutritional and Metabolic Diseases

Central Study Contacts

April Freeman

CONTACT

415-343-5986; EA@sprucebio.com

Study Design

• Study Type: expanded access
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: July 23, 2026
• First Posted: July 29, 2026
• Last Updated: July 29, 2026

Record last verified: 2026-07