FDA Puts Hold on LYS-SAF302 Gene Therapy Trial for Sanfilippo Type A

The U.S. Food and Drug Administration (FDA) has issued a hold on Lysogene‘s trial of its gene therapy candidate LYS-SAF302 for Sanfilippo syndrome type A.

LYS-SAF302 is a one-time treatment meant to deliver a healthy copy of the SGSH gene, which is defective in Sanfilippo type A. Dosing began in the U.S. and in Europe last year in the AAVance Phase 2/3 clinical trial (NCT03612869), and 19 out of the 20 patients enrolled have been treated. The hold will have “no anticipated impact on the current clinical trial timelines,” the company said in a press release.

Its investigational gene therapy is injected directly into the brain, and the hold follows MRI scans that showed localized findings at these intracerebral — into the brain — injection sites. The fact that these findings are localized specifically to the injection sites implies a connection to the injections themselves. To date, “no clinical symptoms have been observed that could be directly attributed to the observed MRI findings,” Lysogene stated.

The company added that it reported all findings to the relevant authorities, such as ethics committees and the trial’s Data Safety Monitoring Board.

Medical teams in charge of patient care will continue to closely monitor all trial participants. Lysogene reported having discussed a way to move forward with the FDA, and will gather additional information about the safety of LYS-SAF302.

Sanfilippo syndrome, also known as mucopolysaccharidosis type III, renders the body unable to break down large sugar molecules called glycosaminoglycans. These then build up to toxic levels in the neurons of those with the condition. The syndrome comprises four subtypes, with type A the most common.

“I would like to thank the families for their participation in the study,” Sophie Olivier, MD, Lysogene’s chief medical officer, said. “We consider patient safety the utmost priority and believe the clinical development of LYS-SAF302 can offer meaningful benefits to patients with this devastating disease. We will now focus on gathering additional information and continue working with FDA to determine the appropriate path forward.”