Spruce Biosciences announced the acquisition of tralesinidase alfa enzyme replacement therapy (TA-ERT) for the treatment of Sanfilippo Syndrome Type B (MPS IIIB), marking a strategic shift for the company toward neurological disorders with significant unmet medical needs. The company plans to submit a Biologics License Application (BLA) to the U.S. Food and Drug Administration (FDA) in the first half of 2026.
MPS IIIB is a neurodegenerative and ultimately fatal genetic disease with no currently approved treatments. TA-ERT has shown promising results in clinical trials, significantly and durably normalizing cerebral spinal fluid (CSF) heparan sulfate non-reducing end (HS-NRE) levels over a five-year period.
"This is truly a transformative moment for Spruce as we focus our expertise in rare disease on a potential near-term commercial opportunity with TA-ERT in MPS IIIB," said Javier Szwarcberg, M.D., M.P.H., Chief Executive Officer of Spruce. "This new strategy opens a new chapter in our mission to provide transformative and life-changing therapies to patients affected by serious conditions with significant unmet medical need."
Regulatory Pathway and Clinical Progress
In a significant regulatory development, the FDA has confirmed that HS-NRE could be used as a surrogate biomarker reasonably likely to predict clinical benefit and could serve as a basis for accelerated approval. This alignment was achieved during a Type C meeting with the FDA in March 2024.
The FDA also confirmed that the completed clinical and non-clinical studies of TA-ERT were sufficient for a BLA submission, providing guidance around key design elements of a confirmatory trial, which must be initiated prior to potential accelerated approval.
TA-ERT has already received fast-track designation, rare pediatric disease designation, and orphan drug designation in both the U.S. and European Union, highlighting the therapy's potential importance for this patient population.
Mechanism of Action and Treatment Approach
TA-ERT is a fusion protein comprised of recombinant human alpha-N-acetylglucosaminidase (rhNAGLU) with modified human insulin-like growth factor 2 via an amino acid linker. The therapy is intended as an enzyme replacement for patients with MPS IIIB who lack rhNAGLU enzyme activity.
The acquisition includes an exclusive worldwide license agreement with BioMarin Pharmaceutical Inc. for TA-ERT and other enzyme replacement therapy products, positioning Spruce to potentially deliver the first approved treatment for MPS IIIB.
Commercial Strategy
Spruce intends to build a highly specialized commercial and medical affairs organization to support the commercialization of TA-ERT if approved. The company believes this market can be effectively addressed with a modest-sized and targeted patient-centric field team, as a relatively small number of clinicians and specialists treat most patients with MPS IIIB.
"The vision of the Spruce leadership team and their unrelenting commitment to serving patient communities with meaningful unmet need is on full display with the acquisition of TA-ERT," said Mike Grey, Executive Chairman of Spruce. "The confidence and support shown by our Board underscore the immense potential of the company's new portfolio and direction."
Spruce seeks to commercialize TA-ERT throughout the developed world, including North America, the European Union, the United Kingdom, Latin America, Turkey, Asia, and other international markets. The company plans to establish its own commercial organization in the U.S., EU, and the UK, while seeking regional strategic collaborations and a network of third-party distributors in other international markets.
Financial Position
As of December 31, 2024, Spruce reported cash and cash equivalents of $38.8 million. The company expects its cash runway to fund its current operating plan through the end of 2025. The company has 42.2 million shares of common stock issued and outstanding, with 21.4 million shares reserved for issuance of warrants and equity securities.
Following the announcement, Spruce's stock was trading at $0.26 in pre-market hours, down 17.72 percent on the Nasdaq, reflecting investor uncertainty about the strategic shift.
Looking Forward to Potential Approval
With the BLA submission planned for the first half of 2026, Spruce is positioning itself at the forefront of addressing a serious rare disease with no current FDA-approved treatments. The company's focus on diseases with well-understood biology is intended to increase the probability of success in its development programs.
For patients and families affected by MPS IIIB, the acquisition of TA-ERT by Spruce represents a potential breakthrough in treatment options for this devastating condition, potentially changing the trajectory of the disease and improving quality of life for those affected.
