Spur Therapeutics Presents Positive Phase 1/2 Data on FLT201 Gene Therapy for Gaucher Disease at ESGCT Congress

Spur Therapeutics has announced promising data from its ongoing Phase 1/2 GALILEO-1 trial of FLT201, a novel adeno-associated virus (AAV) gene therapy for Gaucher disease type 1. This therapy has shown significant and lasting reductions in glucosylsphingosine (lyso-Gb1), a key biomarker for Gaucher disease, and improvements in bone marrow burden. Additionally, there have been either improvements or maintenance of blood counts and organ volume in patients who received a single infusion of FLT201. The trial has demonstrated favorable safety and tolerability across all patients.

FLT201 aims to address the unmet needs in Gaucher disease type 1, which is characterized by the buildup of harmful substrates such as glucosylceramide (Gb-1) and glucosylsphingosine (lyso-Gb1) due to a deficiency in the enzyme glucocerebrosidase (GCase). Current treatments do not adequately address symptoms like bone disease, organ enlargement, and fatigue, which many patients continue to experience. FLT201, leveraging Spur's proprietary AAVS3 capsid, delivers a longer-acting version of the GCase enzyme, aiming to halt disease progression and alleviate symptoms.

The data presented at the European Society of Gene and Cell Therapy (ESGCT) 31st Annual Congress highlighted the following results as of September 27, 2024:

1. **Safety and Tolerability**: FLT201 has been well-tolerated with no serious infusion reactions or dose-limiting toxicities. Any treatment-related adverse events were mild to moderate.

2. **Biomarker Improvements**: Significant reductions in lyso-Gb1 levels, ranging from 42% to 96%, were observed in patients with previously high levels despite years of enzyme replacement therapy (ERT) or substrate reduction therapy (SRT). The levels remained low for over a year in one patient who had well-controlled levels before the trial.

3. **Bone Marrow Burden**: All five patients with severe bone involvement showed substantial improvements, indicating that FLT201 can reach deeper tissues where current therapies are less effective. This is crucial as bone marrow burden correlates with increased fractures, bone pain, and joint replacements.

4. **Organ Volume and Blood Counts**: Improvement or maintenance of spleen and liver volume was noted. Hemoglobin levels, which are a key endpoint in Gaucher disease trials, were maintained for over a year after withdrawing previous treatments. Platelet counts also improved or were maintained post-withdrawal of ERT or SRT.

The Phase 1/2 GALILEO-1 trial, a first-in-human, international, multicenter study, has completed dosing with six patients treated with a single infusion of FLT201 at a dose of 4.5e11 vg/kg. The trial includes ongoing follow-ups to monitor long-term safety and efficacy. One patient with pre-existing neutralizing antibodies was excluded from efficacy analysis, ensuring the robustness of the results.

Spur Therapeutics is preparing to launch a Phase 3 trial for FLT201 by 2025, aiming to further validate these findings and potentially establish a new standard of care for Gaucher disease type 1. The company plans to report additional data from the ongoing Phase 1/2 trial in the first half of 2025.

Gaucher disease affects around 18,000 individuals across the US, UK, France, Germany, Spain, Italy, and Israel. Despite existing therapies, many patients continue to suffer from significant symptoms. Spur Therapeutics is committed to developing gene therapies that could transform the treatment landscape for chronic and debilitating conditions, including Gaucher disease and other genetic disorders.

Michael Parini, CEO of Spur Therapeutics, emphasized the potential of FLT201 to offer better outcomes than current treatments, reduce the treatment burden, and improve patients' quality of life. With ongoing collaborations with regulators, Spur aims to advance FLT201 into its next phase of clinical development, potentially bringing a new, effective treatment to those affected by Gaucher disease.