Syncona (SYNC) says that its portfolio company, Spur Therapeutics (Spur) has announced positive new data from its Phase I/II GALILEO-1 study of FLT201, its novel gene therapy candidate, in Gaucher disease at the 21st Annual WORLDSymposium in San Diego, CA, USA.

The clinical trial

In Spur’s trial, six patients have been treated in GALILEO-1 with a single infusion of FLT201 at a low dose of 4.5e11 vg/kg and have been followed for between nine and 17 months after dosing. Spur says that all six patients are included in the safety analysis; although one patient with detectable pre-existing neutralising antibodies to the AAVS3 capsid was excluded from the efficacy analysis. Prior to the trial all of the patients had been treated with existing therapies enzyme replacement therapy (ERT) or substrate reduction therapy (SRT).

Positive feedback following end-of-Phase II meeting

SYNC comments that this data follows yesterday’s announcement that Spur had received positive feedback from its end-of-Phase II meeting with the US Food and Drug Administration (FDA), with alignment on the potential to seek accelerated approval based on reductions in glucosylsphingosine (lyso-Gb1), an established biomarker of clinical response in Gaucher disease. Spur says that full approval would be based on a primary endpoint of maintenance or improvement in haemoglobin at one year in the Phase III study, while SYNC comments that the completion of the pivotal stage of the Phase III trial in CY2027 is a key value inflection point for it.

SYNC’s announcement says that, as of 6 December 2024, the data demonstrated:

• Continued favourable safety and tolerability profile, with no infusion reactions, dose limiting toxicities or treatment-related severe adverse events
• Durable reductions in lyso-Gb1, ranging from 33% to 96% in patients who entered the trial with high levels
• Stable lyso-Gb1 levels for more than a year after the withdrawal of prior therapy in the one patient who entered the trial with well-controlled levels.
• Maintenance of normal haemoglobin levels (Phase III primary endpoint) beyond a year after withdrawal of ERT or SRT
• Sustained improvements or maintenance in platelet counts and spleen and liver volume after withdrawal of ERT or SRT
• Improvements in bone marrow burden (BMB) in four of the five patients, indicating the clearance of substrate and reappearance of healthy marrow, and maintenance of BMB in the fifth patient. Previously reported BMB scores have been updated to correct a reporting error by an outside clinical research organisation

Comments from Chris Hollowood, CEO of SYNC’s manager and chair of Spur Therapeutics

“These data further reinforce our belief that FLT201 has the potential to be a first- and best-in-class gene therapy for Gaucher disease. Through a single infusion, FLT201 has shown improvements to symptoms that had been persistent in patients receiving approved therapies for years and in some cases decades. We look forward to the initiation of Spur’s Phase III FLT201 trial later this year, following the company’s recent successful end-of-Phase II meeting with the US FDA.”