Spruce Biosciences (NASDAQ:SPRB) shares surged more than 390% to around $43 following news that the US Food and Drug Administration (FDA) has granted Breakthrough Therapy Designation (BTD) for its tralesinidase alfa enzyme replacement therapy (TA-ERT) for Sanfilippo Syndrome Type B (MPS IIIB).
The designation recognizes the potential of TA-ERT as a first disease-modifying therapy for this ultra-rare and fatal genetic disorder.
Clinical data indicates that the therapy can normalize cerebral spinal fluid heparan sulfate non-reducing end (CSF HS-NRE), stabilize brain volume, and preserve cognitive function in children affected by MPS IIIB.
Sanfilippo Syndrome Type B is a progressive neurodegenerative disorder affecting fewer than 1 in 200,000 people in the United States.
There are currently no FDA-approved treatments for the condition, which typically leads to severe cognitive decline, motor impairment, and a life expectancy of 15 to 19 years.
TA-ERT is designed to restore the deficient enzyme alpha-N-acetylglucosaminidase in the central nervous system, potentially addressing the underlying cause of the disease.
Integrated safety and efficacy data from three clinical studies over five years support the therapy’s potential benefits.
“Receiving US FDA Breakthrough Therapy Designation highlights TA-ERT’s potentially transformative clinical impact as the first disease-modifying therapy to treat MPS IIIB in children impacted by this devastating condition,” Spruce CEO Javier Szwarcberg said in a statement.
Breakthrough Therapy status provides Spruce with intensive FDA guidance, eligibility for rolling submission, priority review, and cross-disciplinary collaboration, all of which could accelerate regulatory approval.
The company plans to submit a Biologics License Application (BLA) for TA-ERT in the first quarter of 2026.