Trieste, Italy – A single treatment with avigbagene parvec, an investigational gene therapy developed by Spur Therapeutics, may help improve bone health in adults living with Gaucher disease, according to new clinical trial data.
The findings come from the completed Phase 1/2 GALILEO-1 trial and its ongoing long-term extension study, GALILEO-2. Researchers reported that a one-time infusion of avigbagene parvec reduced signs of bone marrow disease and improved bone strength in some adults with Gaucher disease type 1 (GD1).
The results were presented in a poster titled “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,” said Pamela Foulds, MD, chief medical officer at Spur Therapeutics, in a company press release.
Understanding Gaucher Disease and Bone Complications
Gaucher disease is caused by mutations in the GBA1 gene, which lead to low activity of the enzyme glucocerebrosidase (GCase). This enzyme is responsible for breaking down certain fatty substances in the body. When GCase is deficient, these fats accumulate inside cells and build up in organs and tissues such as the liver, spleen, and bone marrow, contributing to the disease’s symptoms.
Bone complications are among the most common and debilitating features of Gaucher disease type 1, affecting an estimated 75% to 100% of patients. These complications can include:
- Bone pain
- Low bone mineral density
- Increased fracture risk
- Skeletal abnormalities
Current standard treatments include enzyme replacement therapy (ERT), which supplies patients with a functional version of the missing enzyme, and substrate reduction therapy (SRT), which lowers production of the fatty molecules that accumulate in the disease.
While these therapies can help manage symptoms, they require lifelong treatment and may not fully prevent or reverse bone disease.
“Skeletal disease in Gaucher disease may develop silently and frequently persist even after years of treatment with standard therapy,” said study investigator Pilar Giraldo, MD, PhD, a hematologist at Hospital Universitario Quironsalud de Zaragoza in Spain. “There is a clear need to address bone health as part of therapeutic innovation.”
How Avigbagene Parvec Works
Avigbagene parvec, previously known as FLT201, is designed to deliver a modified version of the GBA1 gene through a one-time intravenous infusion. The therapy enables the body to produce a more stable form of the GCase enzyme than the naturally occurring version.
According to Foulds, the increased stability of the engineered enzyme in the bloodstream and tissues may allow it to better reach difficult areas such as bone tissue, potentially improving outcomes where existing therapies fall short.
Trial Results Show Sustained Benefits
In the GALILEO-1 study, six adults with Gaucher disease type 1 who had been receiving ERT or SRT for at least two years received a low-dose infusion of avigbagene parvec. All participants later enrolled in the GALILEO-2 extension study, which will follow them for up to five years.
About three months after treatment, four participants were able to stop their standard therapies altogether. Separate data presented by Spur showed that these patients remained off standard treatment for 22 to 26 months while maintaining stable disease control or continuing to improve.
Researchers also observed:
- Sustained increases in GCase enzyme activity
- Long-term reductions in lyso-Gb1, a key marker of Gaucher disease burden
- Stable or improved blood measures
- Reduced liver and spleen enlargement
Encouraging Signs for Bone Health
The latest analysis focused specifically on bone-related outcomes in the four patients who discontinued standard therapy.
At the start of the study, all four had moderate to severe infiltration of fat-laden cells in the bone marrow, placing them at increased risk for bone complications. They also had low bone mineral density.
Following treatment:
- One patient experienced a clinically meaningful reduction in bone marrow infiltration, with improvements appearing within three months and lasting for at least two years.
- The remaining patients generally maintained stable bone marrow disease throughout the follow-up period.
- Two patients showed improvements in bone density, including one whose other disease symptoms had already been well controlled with conventional therapies.
According to Spur, these findings suggest that bone disease can persist even when other Gaucher symptoms appear stable, underscoring the need for therapies that specifically target skeletal complications.
“This study provides early evidence that bone disease in Gaucher patients can be improved beyond what is achievable with current therapies,” Giraldo said. “This may ultimately translate into reduced fracture risk and decreased pain for patients.”
Phase 3 Trial Underway
Avigbagene parvec is now being evaluated in the Phase 3 GALILEO-3 trial, which is expected to enroll approximately 45 patients with Gaucher disease type 1.
The study is designed to confirm the therapy’s safety and effectiveness after patients discontinue standard treatments and could support both accelerated and full regulatory approval.
“This data contributes to the strong body of evidence supporting FLT201,” Foulds said. “We look forward to demonstrating this profile in a larger dataset through the Phase 3 trial we initiated this year.”
Contact
Pilar Giraldo, MD, PhD
Hospital Quironsalud de Zaragoza
+34 976 72 00 00