Cause of Death Unknown in Child Participating in LYS-SAF302 Gene Therapy Trial

One of the children participating in the Phase 2/3 trial of LYS-SAF302, Lysogene’s gene therapy candidate for Sanfilippo syndrome type A, has died.

The exact cause of death is currently unknown, and there is no clear evidence yet to indicate it might be related to treatment, according to a company press release. Additional information is now being collected.

Lysogene stated it “is profoundly saddened by the passing of this child and extends its deepest sympathies to the family,” and guaranteed it “remains committed to the LYS-SAF302 development program and the Sanfilippo patient community.”

The Phase 2/3 trial, called AAVance (NCT03612869), is assessing the safety and efficacy of LYS-SAF302 — a one-time gene therapy that aims to deliver a functional copy of the SGSH gene, which is faulty in patients with Sanfilippo type A — in 20 children, 6 months or older, with the disease.

Since dosing started last year in the U.S. and in Europe, 19 of the 20 children participating in the trial have received the therapy, which was directly injected to both sides of the brain in a single session of image-guided surgery.

After MRI scans found abnormalities in brain regions located near the therapy’s injection sites, the U.S. Food and Drug Administration placed the trial on clinical hold in June for safety reasons. No clinical symptoms were found to be connected to these abnormalities, Lysogene stated. At the time the clinical hold was put in place, the company assured the hold should have no impact on the trial’s timelines.

After informing all relevant authorities and reporting all findings, medical teams continued to closely monitor participants’ health status. Lysogene announced the child’s death a few months after the trial was placed on hold.

The company said it will continue to diligently monitor the remaining 18 children who received LYS-SAF302 in the study, while gathering additional data to attempt to determine the cause of death.

Lysogene also said it will continue providing regular updates on AAVance, as well as disclosing additional information on LYS-SAF302 that may be relevant to the therapy’s clinical development program.