Intracerebroventricular Tralesinidase Alfa in Children With Mucopolysaccharidosis Type IIIB (TrAnsform)

A Phase 3, Randomized, Single-blind, Parallel Group, Controlled, Multicenter Study to Evaluate the Safety, Tolerability, and Efficacy of Intracerebroventricular Tralesinidase Alfa Treatment Compared to Standard of Care in Mucopolysaccharidosis Type IIIB (MPS IIIB, Sanfilippo Syndrome Type B)

The primary objectives of this study are to evaluate the effects of Tralesinidase Alfa (TA) on cognition

Study Overview

• Status: Not yet recruiting
• Conditions: MPS IIIB
• Intervention / Treatment: Drug: Tralesinidase alfa (TA)

• Study Type: Interventional
• Enrollment (Estimated): 14
• Phase: Phase 3

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

Has a diagnosis of MPS IIIB confirmed by deficient NAGLU enzyme activity during screening.

Has nonattenuated severe MPS IIIB by the Genotype and Clinical Assessment Committee.

Is ≥1 and ≤5 years of age with BSID-III-C raw score of <70. Is male or female as identified at birth.

Exclusion Criteria:

Genotyped for a known MPS IIIB variant associated with an attenuated phenotype or has a sibling with a known attenuated phenotype.

Has another neurological illness that may have caused cognitive decline (e.g., trauma, meningitis, or hemorrhage) before study entry.

Has received stem cell, gene therapy, or enzyme replacement therapy for MPS IIIB.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: Control
Experimental: Tralesinidase alfa (TA)	Drug: Tralesinidase alfa (TA); TA study drug is a sterile solution for ICV infusion.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from Baseline in Bayley Scales of Infant and Toddler Development, Third Edition, Cognition Domain (BSID-III-C) Raw Score	The BSID-III-C is a standardized tool that evaluates cognitive development in young children, capturing skills such as processing speed, problem solving, and play. Raw scores are used to sensitively measure individual change over time, independent of age. Assessments are administered by a trained, blinded rater and reviewed by a central blinded rater. The endpoint is the difference in mean change from baseline in BSID-III-C raw score between the tralesinidase alfa and control arms at Week 260	Baseline to Week 260 (approximately 5 years)

Collaborators and Investigators

• Sponsor: Spruce Biosciences

Study record dates

Study Major Dates

• Study Start (Estimated): December 1, 2026
• Primary Completion (Estimated): August 1, 2033
• Study Completion (Estimated): August 1, 2033

Study Registration Dates

• First Submitted: April 28, 2026
• First Submitted That Met QC Criteria: May 6, 2026
• First Posted (Actual): May 12, 2026

Study Record Updates

• Last Update Posted (Actual): May 12, 2026
• Last Update Submitted That Met QC Criteria: May 6, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Metabolism, Inborn Errors; Genetic Diseases, Inborn; Metabolic Diseases; Connective Tissue Diseases; Carbohydrate Metabolism, Inborn Errors; Lysosomal Storage Diseases; Mucinoses; Mucopolysaccharidoses; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Nutritional and Metabolic Diseases; Skin and Connective Tissue Diseases; Mucopolysaccharidosis III
• Other Study ID Numbers: 250-301

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No