Groups invest $5.5M to expand access to experimental Sanfilippo B drug
Funds bring Spruce's TA-ERT to children who miss trial criteria
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Cure Sanfilippo Foundation and the National MPS Society are investing $5.5 million to expand access to an experimental treatment for children with Sanfilippo syndrome type B.
The funding will support a U.S.-based expanded access program expected to launch as early as October for tralesinidase alfa (TA-ERT), an investigational enzyme replacement therapy developed by Spruce Biosciences.
This program (NCT07733856) will give pediatric patients who do not qualify for Spruce’s planned confirmatory clinical trial access to the therapy ahead of potential U.S. approval, with Spruce expecting to file for regulatory clearance next year.
“We are deeply grateful to Cure Sanfilippo Foundation and the National MPS Society for their partnership and their conviction in Spruce’s development of TA-ERT,” Samir Gharib, president and chief financial officer of Spruce, said in a company press release. “Their support helps us expand access to investigational TA-ERT for children with [Sanfilippo B] who urgently need treatment options today, while we continue our work to bring this therapy to all eligible patients.”
How Sanfilippo B affects the brain
Sanfilippo type B, also called mucopolysaccharidosis type 3B, is caused by a deficiency in alpha-N-acetylglucosaminidase (NAGLU), an enzyme that normally breaks down the sugar molecule heparan sulfate inside cells.
When NAGLU is missing, heparan sulfate builds up to toxic levels in the spinal fluid and brain, driving neurodegeneration. This leads to a range of developmental and behavioral problems that worsen over time, including a form of childhood dementia.
Currently, there are no approved treatments for Sanfilippo B. As an enzyme replacement therapy, or ERT, Spruce’s TA-ERT is designed to provide patients with the missing NAGLU enzyme.
The therapy, administered through a procedure called intracerebroventricular infusion directly into the brain’s fluid-filled cavities, is expected to help clear heparan sulfate from cells and slow disease progression.
Last year, the U.S. Food and Drug Administration (FDA) granted TA-ERT a breakthrough therapy designation for the treatment of children with Sanfilippo B, which is meant to accelerate its clinical development and regulatory review.
“Every day without treatment matters for a child living with Sanfilippo syndrome,” said Cara O’Neill, MD, chief science officer and co-founder of the Cure Sanfilippo Foundation. “As both a physician and a parent in this community, I know the urgency families feel as they watch this devastating disease take abilities from their children.”
TA-ERT has been studied in three clinical trials, an initial Phase 1/2 study (NCT02754076) and two extension studies (NCT03784287 and NCT05492799), involving 22 children with Sanfilippo B, ages 2-9.
Early data showed that the ERT normalized heparan sulfate levels and slowed cognitive decline and brain tissue loss. More recently, long-term data demonstrated a stabilization of cognitive function for up to six years.
“The encouraging clinical data for TA-ERT offer meaningful hope, and our investment reflects the Foundation’s deep commitment to advancing rigorous science while bringing promising therapies within reach for children who need time-sensitive access,” O’Neill said.
Spruce plans to use these data to support an application seeking accelerated approval of TA-ERT for children with Sanfilippo B. Accelerated, or conditional, approval allows a therapy to enter the market based on preliminary clinical trial evidence supporting its safety and effectiveness. Full approval is dependent on additional clinical trial findings confirming its benefits.
The Phase 3 TrAnsform study (NCT07579910), designed to evaluate TA-ERT’s safety and efficacy in 14 children, ages 1-5 years, with Sanfilippo type B, is expected to launch next year and serve as a confirmatory trial, providing the required data for full approval.
Eligible participants must be classified as nonattenuated (meaning the disease is rapidly progressing rather than slowed or mild) with a Bayley’s Scales of Infant Development-3 (BSID-III) score below 70, indicating a moderate-to-severe developmental delay.
Expanded access criteria and community support
The new $5.5-million investment in Spruce will partly fund TA-ERT’s expanded access program for up to 10 children in the U.S. who are not eligible for TrAnsform, including those with attenuated (less severe) or more severe Sanfilippo B.
To qualify for the expanded access program, a child who is 1 to 5 years old must have a confirmed diagnosis of Sanfilippo B and a BSID-III score of at least 70, indicating mild developmental delay. Children older than 5 years, regardless of cognitive level, are also eligible. Participants will receive the experimental therapy once weekly for up to one year, or until TA-ERT becomes commercially available if approved.
Fundraising efforts by the foundations and the community supported the start-up activities of the expanded access program earlier this year. This included manufacturing the drug product to expedite access for children with Sanfilippo B ahead of potential FDA accelerated approval.
“Advocacy organizations can and should help bridge the gap between scientific progress and patient access,” said Terri Klein, president and CEO of the National MPS Society. “We are grateful to partner with Spruce and the Cure Sanfilippo Foundation to bring a potential treatment closer to the children and families who are counting on it.”
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