Cure Sanfilippo Foundation and the National MPS Society have agreed to make a combined $5.5 million strategic investment in Spruce Biosciences (Nasdaq: SPRB), according to a press release from the company. The proceeds will partially fund an Expanded Access Program (EAP) for tralesinidase alfa enzyme replacement therapy (TA-ERT), an investigational treatment for Sanfilippo Syndrome Type B, also known as mucopolysaccharidosis Type IIIB (MPS IIIB).

Spruce expects to initiate the TA-ERT EAP as early as the fourth quarter of 2026. The program is designed as an open-label, single-arm early access initiative to provide TA-ERT to children in the United States with MPS IIIB who are not eligible to enroll in a separate confirmatory study. The program is expected to enroll approximately 10 participants across U.S. sites, with TA-ERT administered weekly via an intracerebroventricular delivery device.

To be eligible, a child must have a confirmed MPS IIIB diagnosis and be between 12 and 60 months of age with a specific cognitive score, or older than 60 months regardless of cognitive level. Participation is anticipated to continue for up to approximately one year or until TA-ERT becomes commercially available, if approved.

MPS IIIB is a rare genetic disease estimated to affect fewer than one in 200,000 people in the United States. There are currently no FDA-approved therapies for the condition. Estimated life expectancy for individuals with MPS IIIB ranges from 15 to 19 years of age.

TA-ERT has previously received Breakthrough Therapy Designation, Rare Pediatric Disease Designation, Fast Track Designation, and Orphan Drug Designation from the FDA. The therapy has been administered to 22 individuals in prior clinical studies, with six years of integrated safety data collected.

"This investment is a powerful expression of what we can accomplish when industry and the patient community work together," said Samir Gharib, President and Chief Financial Officer of Spruce Biosciences.