Lysogene Receives FDA Fast Track Designation for LYS-SAF302 Gene Therapy in MPS IIIA

Lysogene, a pioneering Phase 3 gene therapy platform company targeting central nervous system (CNS) diseases, announced that the U.S. Food and Drug Administration (FDA) has granted Fast Track Designation to its LYS-SAF302 program for the treatment of mucopolysaccharidosis Type IIIA (MPS IIIA). LYS-SAF302, a second-generation gene therapy, is designed to deliver a functional copy of the SGSH (N-sulfoglucosamine sulfohydrolase) gene to the brain through a one-time direct-to-CNS administration, and is being investigated in the international Phase 2/3 clinical trial AAVance (NCT03612869).

Karen Aiach, Founder and Chief Executive Officer said: “MPS IIIA is a lethal neurological disease with
debilitating symptoms for which there is currently no treatment. The FDA’s recognition of LYS-SAF302’s
potential to improve neurocognitive deficits in children with MPS IIIA represents an important achievement
for Lysogene and the patient community.” Karen Aiach added: “We are also pleased to announce the
treatment of the 17th patient with LYS-SAF302, which once again demonstrates our capacity to execute
with quality and speed. LYS-SAF302 is the flagship of our differentiated direct-to-CNS gene therapy
platform, which has been validated not only by our partner Sarepta, but also by the scientific community.
We are fully dedicated to continue the full speed development of LYS-SAF302, as well as all the other
programs in our pipeline.”

The Fast Track program facilitates the development and accelerates the review of new drugs for serious
conditions, which have the potential to address unmet medical needs. The purpose is to expedite the
availability of new treatment options for patients. A product that receives Fast Track designation is eligible
for more frequent interactions with FDA, potential eligibility for accelerated approval, priority review, and
rolling Biologics License Application (BLA) review

“This Fast Track designation demonstrates the regulators’ sustained interest in Lysogene’s cutting edge in
vivo gene therapy program. LYS-SAF302 has previously received Orphan Drug Designations for the
treatment of MPS IIIA in the European Union in 2014 and in the US in 2015, as well as Rare Pediatric
Disease Designation in the US” added Marie Deneux, Chief Regulatory Officer. “In the complex field of
gene therapy for neurodegenerative diseases, a continued communication with FDA is essential.”

The AAVance Phase 2/3 clinical study is designed as an open-label, single-arm, multicenter study of LYSSAF302 for the treatment of MPS IIIA. The study will include 20 patients with the severe classical form of
MPS IIIA and has been extensively discussed upfront with key opinion leaders, regulators and health
technology assessment bodies, as well as with patient representatives. As of today, 17 patients have been
treated out of the total of 20. The primary objective is to assess the drug efficacy in improving the
neurodevelopmental status of patients after 24 months, compared to the expected evolution based on
natural history data. Safety, tolerability, effect on behavior, sleep and quality of life will also be collected
as secondary endpoints. Lysogene has also set up the sub study, PROVide, collecting supportive video
outcomes in the home environment.