NEW YORK – Spur Therapeutics on Monday said it received positive feedback during an end-of-Phase II meeting with the US Food and Drug Administration, laying the groundwork to evaluate its gene therapy for Gaucher disease type 1 in a Phase III trial slated for launch in the second half of the year.
The London-based company said its development plans for the gene therapy, FLT201, aligns with the FDA's in that a single-arm Phase III trial could support accelerated or traditional approval. With this gene therapy, the company aims to treat Gaucher disease, a rare and inherited condition caused by a mutation in the GBA1 gene that leads to a deficiency in the enzyme Gcase necessary for metabolizing certain lipids. FLT201 is designed to deliver an engineered longer-acting version of this enzyme, called GCase85, using an adeno-associated virus vector.
"We are very pleased with the outcome of our end-of-Phase II discussion with the FDA, providing us with a clear path forward," Spur CEO Michael Parini said in a statement. "We are moving expeditiously to get the Phase III trial underway."
Within the Phase III trial, patients with Gaucher disease type 1, who have been on a stable dose of either enzyme replacement therapy or substrate reduction therapy for at least two years, will receive a single infusion of FLT201. They will be taken off of the previous therapies after a set period post-gene therapy administration. Investigators will compare patients' outcomes in the trial against baseline assessments, making patients their own comparators.
If Spur decides to seek traditional approval, it could show in the Phase III trial that the gene therapy maintained or improved hemoglobin one year post-treatment, which is a well-established regulatory endpoint in Gaucher disease, the firm said. The FDA also provided positive feedback on the possibility of using reductions in glucosylsphingosine (lyso-Gb1) after six months as a surrogate endpoint that facilitates accelerated approval. The company plans to monitor other secondary and exploratory endpoints in the trial including platelet counts, liver and spleen volume, assessments of bone health, and patient-reported outcomes on pain and fatigue.
Spur plans to complete site selection later this month and expects to enroll patients at more than 45 sites in the US, Canada, UK, Europe, Israel, and Latin America. It hopes to enroll around 40 to 45 adult patients with Gaucher disease type 1 in the trial.
Spur launched last year as a rebrand of Freeline Therapeutics, after it acquired another gene therapy company, SwanBio Therapeutics.
Results from the Phase I/II GALILEO-1 trial, initially launched by Freeline, support advancing FLT201 into a Phase III trial. Patients in the GALILEO-1 trial treated with the gene therapy maintained normal hemoglobin levels beyond a year after withdrawal of previous treatments and had rapid and sustained reductions in lyso-Gb1, the company said.