Four adults with type 1 Gaucher disease who received a single low dose of avigbagene parvec (FLT201; 4.5e11 vg/kg) discontinued prior enzyme replacement or substrate reduction therapy within 11 weeks and remained off chronic therapy for 19 to 23 months at data cutoff (Aug. 25, 2025). Across the cohort, lyso-Gb1 levels showed rapid, sustained reductions; hemoglobin remained normal; platelet counts were stable or improved; and liver and spleen volumes were stable. No dose-limiting toxicities were reported over the follow-up period.
Spur Therapeutics reported the updated Phase 1/2 GALILEO-1 data at the ESGCT Annual Congress and outlined plans to initiate a Phase 3 study in the first half of 2026. The company has alignment with the FDA on a single-arm trial design intended to support both potential accelerated and full approval. The package reflects an explicit bid to move Gaucher care from chronic infusions to a one-time gene therapy administered at a comparatively low vector dose, with biomarker and clinical stability used to anchor the efficacy case.
Strategically, this is an expansion play into an entrenched market using a durability narrative and operational simplicity as differentiators. The decision to pursue a single-arm Phase 3 signals confidence that withdrawal from standard therapy plus sustained control of lyso-Gb1 and hematologic parameters will be persuasive against historical benchmarks. It also underscores a regulatory bet: that lyso-Gb1 can function as a credible surrogate alongside hard clinical measures in a setting where randomized ERT-controlled trials would be slow, costly, and potentially unacceptable to patients. The tension is obvious—n is four, long-term AAV safety scrutiny persists, and a low-dose approach must still demonstrate consistent transduction and phenotypic impact across a broader, more heterogeneous population.
If the Phase 3 proceeds as described, sites should expect a gene therapy operational footprint: vector handling, potential prophylactic immunosuppression, antibody screening, centralized biomarker testing, and long-term follow-up obligations. CROs will need rare-disease recruitment strategies that can swiftly transition patients off ERT/SRT under tight rescue criteria while maintaining rigorous imaging and lab schedules. Regulators will face familiar questions about surrogate endpoints, durability thresholds, and postmarketing commitments in chronic metabolic diseases. Vendors providing lyso-Gb1 assays, imaging quantitation of organ volumes, and real-time safety monitoring stand to be embedded in the design. Infusion centers and specialty pharmacies serving chronic ERT may ultimately see demand shifts if gene therapy adoption meaningfully penetrates.
The next milestones are clarity on Phase 3 endpoints, rescue protocols, and statistical plans for historical-control comparisons, plus expanded safety data beyond two years. Key risks include hepatotoxicity signals, variability in response tied to preexisting antibodies, the irreversibility of AAV dosing without re-dosing options, and manufacturing reproducibility at commercial scale. Pricing and outcomes-based contracting will be consequential in a category with established therapies and predictable disease control. Watch for parallel scientific advice with European regulators, specifics on inclusion criteria that reflect real-world Gaucher heterogeneity, and any movement toward multi-center readiness that demonstrates site-level feasibility for a one-time therapy in a historically infusion-dependent population.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
