Gene therapy may improve bone health in Gaucher disease
Spur’s one-time avigbagene parvec shows promise in type 1 trial
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One-time treatment with avigbagene parvec, a gene therapy being developed by Spur Therapeutics, may improve bone health in adults with Gaucher disease.
That’s according to data from a now-completed Phase 1/2 clinical trial, GALILEO-1 (NCT05324943), and its ongoing long-term extension study, GALILEO-2 (NCT06545136), showing that a single infusion of avigbagene parvec reduced signs of bone marrow involvement and improved bone strength in some adults with Gaucher disease type 1 (GD1).
Spur shared the findings in a poster, “Impact of avigbagene parvec (FLT201) on markers of bone health in adults with Gaucher disease type 1,” at the International Working Group on Gaucher Disease 2026 symposium, held May 3-6 in Trieste, Italy.
“These encouraging results highlight the potential beneficial effect of FLT201 on bone disease in GD1 patients,” Pamela Foulds, MD, Spur’s chief medical officer, said in a company press release.
Gaucher disease is caused by mutations in the GBA1 gene that result in deficient activity of the enzyme glucocerebrosidase (GCase), which is needed to break down certain fatty molecules. As a result, these fatty molecules accumulate to toxic levels in certain cells, which then infiltrate various tissues and organs — including the bone marrow, liver, and spleen — driving Gaucher disease symptoms.
Addressing bone health
Bone complications are among the most common manifestations of Gaucher disease, affecting an estimated 75% to 100% of people with Gaucher type 1. Symptoms include bone pain, reduced bone density, increased fracture risk, and skeletal abnormalities.
The standard treatment for Gaucher is enzyme replacement therapy (ERT), which delivers a healthy version of the GCase enzyme to the body, or substrate reduction therapy (SRT), which reduces the production of the fatty molecules that GCase would normally break down.
However, such therapies require regular, lifelong dosing that can be burdensome for patients, and bone abnormalities may persist despite years of continuous treatment.
“Skeletal disease in Gaucher disease may develop silently and frequently persist even after years of treatment with standard therapy, so we recognize the clear need to address bone health as part of therapeutic innovation,” said study author Pilar Giraldo, MD, PhD, an investigator in the trials and a hematologist at Hospital Universitario Quironsalud de Zaragoza in Spain.
Avigbagene parvec, previously known as FLT201, is designed to deliver a modified version of the GBA1 gene, allowing the body to produce a more stable version of GCase than the naturally occurring enzyme. Given as a one-time intravenous (into-the-vein) infusion, the therapy aims to overcome the limitations of current standard treatments.
Foulds said the therapy’s potential benefit may be related to “the extended stability of GCase in the blood stream and within tissues,” which “may allow for deeper penetration into hard-to-reach tissues such as bone.”
In GALILEO-1, a single infusion of low-dose avigbagene parvovec was given to six adults with Gaucher disease type 1 who had been on ERT or SRT for at least two years. After completing GALILEO-1, all chose to enter GALILEO-2, where they are being followed for up to five years.
Within about three months of the infusion, four participants were able to discontinue their standard treatments. In a separate poster, Spur showed that these patients, who had been off standard therapies for 22-26 months, continued to experience improvements or maintained stable clinical outcomes.
Consistent with earlier data from those four patients, treatment was associated with sustained increases in GCase activity and durable reductions in blood levels of lyso-Gb1, a biomarker of disease burden. Blood problems and liver and spleen enlargement also remained stable or eased.
The newly presented analysis focused on bone-related outcomes in these four patients. All had moderate to severe infiltration of fat-laden cells in the bone marrow at the study’s start, indicating an increased risk of bone complications. They also had low bone mineral density, which is associated with a higher risk of fractures.
After treatment, one patient showed a clinically meaningful reduction in fat-laden cells in the bone marrow, with improvements evident as early as three months and sustained for two years of follow-up. All other participants generally maintained stable bone marrow disease over the two-year period.
Bone density improved for two patients, including one whose other disease symptoms had been well controlled with standard therapies. Spur said the findings confirm that bone disease can persist even in the absence of other disease manifestations.
“This study provides early evidence that bone disease in Gaucher patients can be improved beyond what is achievable with current therapies, which may ultimately translate into reduced fracture risk and decreased pain for patients,” Giraldo said.
Avigbagene parvec is being evaluated in a confirmatory Phase 3 clinical trial, GALILEO-3 (NCT07223944), which may support both accelerated and full approval of the gene therapy for Gaucher disease type 1. The trial expects to enroll about 45 patients and aims to confirm the therapy’s efficacy and safety after discontinuation of standard therapies.
“This data contributes to the strong body of evidence supporting FLT201 and we look forward to demonstrating this profile in a larger dataset through the Phase 3 trial we initiated this year,” Foulds concluded.
