Spruce Biosciences Secures $5.5 Million Strategic Investment to Expand Access to Investigational TA-ERT for Children With Sanfilippo Syndrome Type B
Spruce Biosciences, Inc. (Nasdaq: SPRB), a late-stage biopharmaceutical company focused on developing and commercializing innovative therapies for neurological disorders with significant unmet medical needs, has announced a $5.5 million strategic investment from two leading patient advocacy organizations serving the Sanfilippo and mucopolysaccharidosis (MPS) communities. The investment will be made jointly by the Cure Sanfilippo Foundation and the National MPS Society and is intended to help support broader access to investigational TA-ERT for children living with Sanfilippo Syndrome Type B, also known as mucopolysaccharidosis Type IIIB or MPS IIIB.
The proceeds from the investment will be used in part to fund Spruce’s planned TA-ERT Expanded Access Program (EAP) in the United States. The program is being developed to provide investigational TA-ERT to eligible children who are unable to participate in the therapy’s confirmatory clinical study.
The collaboration represents an important example of pharmaceutical development and patient advocacy organizations working together to address an urgent unmet medical need. For families affected by MPS IIIB, the disease is progressive and devastating, with symptoms that can worsen rapidly during childhood. There are currently no FDA-approved therapies specifically available for the treatment of MPS IIIB, creating a significant need for new treatment options and mechanisms that may alter the course of the disease.
Strategic Investment Supports Expanded Access
Spruce said the strategic financing reflects a shared commitment between the company, Cure Sanfilippo Foundation, and National MPS Society to accelerate access to investigational TA-ERT for children living with MPS IIIB.
The investment follows fundraising and other community efforts led by the two foundations that helped support the initiation of Expanded Access Program preparation earlier in 2026. These activities have included the manufacturing of drug product, with the objective of preparing the therapy for potential access to eligible children and families while Spruce continues to advance its broader clinical and regulatory development program.
Samir Gharib, President and Chief Financial Officer of Spruce Biosciences, expressed appreciation for the support provided by the two organizations. He said the investment demonstrates what can be accomplished when biotechnology companies and patient communities work together around a shared objective.
According to Gharib, the funding will help Spruce expand access to investigational TA-ERT for children with MPS IIIB who urgently need treatment options while the company continues efforts to make the therapy available to all eligible patients if approved.
The partnership also demonstrates the increasingly important role that patient advocacy organizations can play in rare disease drug development. Beyond raising awareness and supporting research, organizations representing rare disease communities can help accelerate access initiatives and provide resources that may support clinical development and expanded access programs.
Addressing a Devastating Rare Neurological Disease
MPS IIIB is a rare inherited metabolic disorder caused by deficiency of the N-acetyl-alpha-glucosaminidase (NAGLU) enzyme. The deficiency leads to the accumulation of certain complex molecules within cells, ultimately contributing to progressive damage across multiple organs and systems.
One of the most serious consequences of MPS IIIB is its impact on the central nervous system. Children with the disease can experience progressive neurodegeneration and deterioration in cognitive and developmental abilities. As the disease advances, affected children may lose previously acquired skills and experience increasing physical and neurological challenges.
Because the condition progresses during childhood, timing can be particularly important for families and physicians. The absence of an FDA-approved treatment specifically for MPS IIIB means that families and clinicians have limited options for addressing the underlying disease.
The development of TA-ERT is therefore being closely watched by the MPS IIIB community. Spruce’s Expanded Access Program is designed to provide an avenue for eligible children who cannot participate in the company’s confirmatory study to potentially receive the investigational treatment while clinical development continues.
Patient Community Emphasizes Urgency
The Cure Sanfilippo Foundation has played an active role in supporting research and development efforts aimed at addressing Sanfilippo syndrome. Cara O’Neill, M.D., Chief Science Officer and Co-Founder of the organization, emphasized the urgency faced by families caring for children with the disease.
O’Neill, who described her perspective as both a physician and a parent within the Sanfilippo community, highlighted the emotional and medical challenges faced by families as they watch the disease progressively affect their children’s abilities.
She said the clinical data generated for TA-ERT provide meaningful hope for the community and that the foundation’s investment reflects its commitment to advancing rigorous scientific research while supporting time-sensitive access to promising investigational therapies.
The Cure Sanfilippo Foundation’s involvement in the investment also underscores the importance of ensuring that advances in rare disease research can reach patients who may not have access to traditional clinical trials.
For families affected by rapidly progressing disorders, clinical trial eligibility criteria can sometimes prevent children from participating even when physicians and families believe an investigational therapy may be relevant. Expanded Access Programs are intended to provide another potential pathway for certain eligible patients under appropriate regulatory and medical oversight.
National MPS Society Supports Patient Access
The National MPS Society, which has supported individuals and families affected by MPS and related disorders for more than five decades, is also participating in the strategic investment.
Terri Klein, President and Chief Executive Officer of the National MPS Society, said the organization has long worked to ensure that families affected by MPS have access to support and that promising scientific research ultimately reaches the patients who depend on it.
The organization views its support for the TA-ERT Expanded Access Program as an opportunity to help bridge the gap between scientific progress and patient access.
Klein emphasized that advocacy organizations can play an important role in supporting efforts that move potential therapies from research and development into the hands of patients who may urgently need new treatment options.
The partnership between the National MPS Society, Cure Sanfilippo Foundation, and Spruce reflects a collaborative model in which patient organizations, biotechnology companies, researchers, physicians, and families work together toward a common objective.
Details of the TA-ERT Expanded Access Program
Spruce’s planned TA-ERT EAP is designed as an open-label, single-arm early access program for children in the United States with attenuated or severe MPS IIIB who are not eligible to participate in the confirmatory study.
To qualify for the program, children must have a confirmed diagnosis of MPS IIIB based on deficient NAGLU enzyme activity. The eligibility criteria include children between 12 and 60 months of age who have a Bayley Scales of Infant and Toddler Development, Third Edition, Cognitive (BSID-III-C) raw score of at least 70.
Children older than 60 months may also be eligible regardless of cognitive level, subject to the program’s other requirements.
Spruce expects the program to enroll approximately 10 participants across clinical sites in the United States.
Under the planned treatment protocol, TA-ERT will be administered once weekly using an intracerebroventricular (ICV) delivery device. This approach is intended to deliver the investigational therapy directly into the cerebrospinal fluid, an important consideration for therapies being developed to address neurological manifestations of rare diseases.
The primary objective of the Expanded Access Program will be to provide early access to TA-ERT for eligible participants who cannot enroll in the confirmatory study while also evaluating the therapy’s safety and tolerability.
Participation in the program is expected to continue for approximately one year or until TA-ERT becomes commercially available, assuming the therapy receives the necessary regulatory approval.
Spruce expects to initiate the TA-ERT Expanded Access Program as early as the fourth quarter of 2026.
Continued Development of TA-ERT
The Expanded Access Program is part of Spruce’s broader clinical development strategy for TA-ERT. While the program is intended to provide potential access to eligible children outside the confirmatory study, it does not replace the controlled clinical development required to establish the safety and efficacy of an investigational therapy.
Data collected through clinical studies and expanded access activities may contribute to the broader understanding of TA-ERT, although the principal purpose of the EAP is early treatment access and assessment of safety and tolerability.
The company’s efforts are taking place against the backdrop of significant unmet medical need in MPS IIIB. Because the disease can progress during critical periods of childhood development, families and advocacy organizations continue to emphasize the importance of accelerating research while maintaining rigorous scientific standards.
The $5.5 million strategic investment from the Cure Sanfilippo Foundation and the National MPS Society provides Spruce Biosciences with additional resources to support its Expanded Access Program for TA-ERT. More broadly, the financing demonstrates the potential impact of collaboration between biotechnology companies and patient advocacy organizations in rare disease development.
For the Sanfilippo community, the planned EAP represents a potential pathway for eligible children who cannot participate in the confirmatory trial to access investigational TA-ERT. For Spruce, it represents another component of the company’s effort to advance a potential treatment for a disease with substantial unmet medical need.
The company’s planned program is expected to begin as early as the fourth quarter of 2026, subject to the necessary preparations and requirements. Approximately 10 children are expected to participate across U.S. sites, with weekly administration of TA-ERT through an ICV delivery device.
As Spruce continues its clinical development program, the company, patient organizations, physicians, and families will be closely focused on the emerging evidence surrounding TA-ERT. While the therapy remains investigational and its safety and efficacy have not yet been established for regulatory approval, the collaboration reflects a shared commitment to advancing research and creating potential treatment opportunities for children living with MPS IIIB.
Additional information about the TA-ERT Expanded Access Program is available through ClinicalTrials.gov.
About Sanfilippo Syndrome Type B (MPS IIIB)
Sanfilippo Syndrome Type B (MPS IIIB) is an ultra-rare, serious, and fatal genetic disease characterized by deficiency in NAGLU, an enzyme required for the catabolism of heparan sulfate in lysosomes. It is estimated that MPS IIIB affects fewer than one in 200,000 people in the United States. The accumulation of toxic levels of cerebral spinal fluid heparan sulfate in the brain is the underlying pathophysiology of MPS IIIB.
Although signs and symptoms of MPS IIIB can vary amongst affected individuals, progressive neurodegeneration typically follows a predictable path to brain atrophy, cognitive and developmental impairment, hyperactivity with aggressive and destructive behavior, delayed speech, hearing loss, and motor skill deficits. Somatic manifestations include coarse facial features, hepatosplenomegaly, and gastrointestinal symptoms.
The final stage of MPS IIIB is typically marked by severe dementia, loss of motor function, and seizure activity, with patients largely bed-ridden and requiring constant care, requiring feeding tubes for hydration and nutrition, and ultimately leading to death. The estimated life expectancy of individuals with MPS IIIB ranges from 15 to 19 years of age. Currently, there are no FDA-approved therapies for MPS IIIB, and management of the disease consists of limited palliative care to improve quality of life.
About Tralesinidase Alfa Enzyme Replacement Therapy (TA-ERT)
TA-ERT is a fusion protein comprised of recombinant human alpha-N-acetylglucosaminidase (rhNAGLU). TA-ERT is intended as an enzyme replacement therapy for the treatment of patients with MPS IIIB who lack rhNAGLU enzyme activity. TA-ERT is anticipated to restore rhNAGLU enzyme activity in the central nervous system following intracerebroventricular injection.
rhNAGLU typically lacks the mannose-6 phosphate (M6P) residues that are essential for efficient cellular uptake via the M6P receptor pathway. As a result, the naked enzyme is poorly absorbed by cells, including neurons. To address this challenge, TA-ERT is fused to an insulin-like growth factor 2 peptide, which binds to the cation-independent M6P on cell surfaces. This fusion enables the enzyme to be internalized and delivered to the lysosome, thereby enhancing its therapeutic potential for treating MPS IIIB.
By restoring NAGLU enzymatic activity and promoting clearance of lysosomal heparan sulfate and heparan sulfate non-reducing end in the brain, TA-ERT therapy is expected to preserve neuronal cell health and potentially halt or slow the neurological decline and improve clinical outcomes in affected patients. TA-ERT has been evaluated in three clinical studies in participants with MPS IIIB: the interventional study 201 and extension studies 202 and 401. TA-ERT has been administered to 22 individuals diagnosed with MPS IIIB, and has demonstrated an adequate safety profile based on integrated six years of safety data.
About Spruce Biosciences
Spruce Biosciences is a late-stage biopharmaceutical company focused on developing and commercializing novel therapies for neurological disorders with significant unmet medical need. Spruce’s lead product candidate, tralesinidase alfa enzyme replacement therapy (TA-ERT), is in late-stage development for the treatment of mucopolysaccharidoses type IIIB (MPS IIIB), or Sanfilippo Syndrome Type B, a devastating pediatric neurodegenerative disorder for which there are no FDA-approved therapies. TA-ERT has received Breakthrough Therapy Designation, Rare Pediatric Disease Designation, Fast Track Designation and Orphan Drug Designation from the FDA, as well as Orphan Drug Designation in the European Union.