Strengthening Lysogene’s Board of Directors

CAMBRIDGE, MA, US, and PARIS, France – November 15, 2018 at 06:00pm – Lysogene

(FR0013233475 – LYS), a pioneering biopharmaceutical company specialized in gene therapy targeting

central nervous system (CNS) diseases, is announcing changes to the composition of its Board of Directors.

Philippe Goupit is joining Lysogene as an independent director.

“We are proud that Philippe is joining Lysogene’s Board of Directors as it begins a new chapter in its development, following the recent partnership with Sarepta. During his 30-year career in the pharmaceutical and biotech industries, Philippe spent over 20 years at Sanofi, where his recent responsibilities included VP of Corporate Licensing. The invaluable experience he gained in mergers and acquisitions and business development fits perfectly with Lysogene’s current Company strategy”, commented Karen Aiach, Founder and Chief Executive Officer of Lysogene.

Philippe graduated from the Paris School of Pharmacy and held several key positions in sales, marketing and regulatory affairs at Servier and then at Pasteur in the vaccines sector. Subsequently, he was appointed VP, Mergers & Acquisitions at Sanofi, a global leader in the healthcare sector. He was also Head of Investor Relations at the Sanofi group for several years. Philippe currently sits on the Board of Directors of MedDay Pharmaceuticals, a pioneer in developing therapies for central nervous system disorders.

“I am deeply honored to be joining Lysogene’s Board of Directors as an independent director. It will enable me to contribute to the substantial efforts undertaken by the Company for a number of years to provide patients with breakthrough therapeutic options in diseases for which there is currently no available treatment,” commented Philippe Groupit.

Lysogene’s Board of Directors now consists of fully independent directors, except for Karen Aiach. Philippe has replaced Rafaèle Tordjman on the Board of Directors with effect from October 25, 2018 and has also been appointed a member of the Audit Committee. Rafaèle had been a member of Lysogene’s Board of Directors since May 9, 2014, initially as the permanent representative of Sofinnova Partners, and then as an independent. “I would like to express my gratitude to Rafaèle on behalf of the entire Board of Directors and the Lysogene team, for her tremendous contribution to the Company’s development”, added Karen Aiach.

“We are delighted to welcome Phillippe to the Board of Lysogene and offer our sincere thanks to Rafaele. The appointment of Philippe, in addition to Peter Lichtlen earlier in the year, is an important evolution and strengthening of the Board as the Company evolves to being a Leading gene therapy Company in Europe and builds on our recent transformative deal with Sarepta.” said Annette Clancy, Chair of the Board of Lysogene.

Lysogene is also announcing the departure of Philippe Mendels-Flandre, who joined the company as Chief Operating Officer and is leaving to pursue a new venture. “We would like to thank Philippe for his significant contribution to Lysogene’s development and we wish him all the best with his future plans,” concluded Karen Aiach.

About Lysogene

Lysogene is a gene therapy company focused on the treatment of orphan diseases of the central nervous system (CNS). The company has built a unique capability to enable a safe and effective delivery of gene therapies to the CNS to treat lysosomal diseases and other genetic disorders of the CNS. A pivotal clinical trial in MPS IIIA in partnership with Sarepta Therapeutics, Inc. and a phase 1-2 clinical trial in GM1 Gangliosidosis are in preparation. In accordance with the agreements signed between Lysogene and Sarepta Therapeutics, Inc., Sarepta Therapeutics, Inc. will hold exclusive commercial rights to LYS-SAF302 in the United States and markets outside Europe, and Lysogene will maintain commercial exclusivity of LYS-SAF302 in Europe. Lysogene is also collaborating with a major partner to define the strategy of development for the treatment of Fragile X syndrome, a genetic disease related to autism. www.lysogene.com.

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Forward looking statement

This press release may contain certain forward-looking statements. Although the Company believes its expectations are based on reasonable assumptions, all statements other than statements of historical fact included in this press release about future events are subject to (i) change without notice, and (ii) factors beyond the Company’s control. These statements may include, without limitation, any statements preceded by, followed by or including words such as “target,” “believe,” “expect,” “aim,” “intend,” “may,” “anticipate,” “estimate,” “plan,” “project,” “will,” “can have,” “likely,” “should,” “would,” “could” and other words and terms of similar meaning or the negative thereof. Forward-looking statements are subject to inherent risks and uncertainties beyond the Company’s control that could cause the Company’s actual results, performance or achievements to be materially different from the expected results, performance or achievements expressed or implied by such forward-looking statements. A further list and description of these risks, uncertainties and other risks can be found in the Company’s regulatory filings with the French Autorité des Marchés Financiers, including in the 2017 registration document (Document de référence), registered with the French Markets Authorities on June 4, 2018, under number R. 18-047, and future filings and reports by the Company. Furthermore, these forward-looking statements are only as of the date of this press release. Readers are cautioned not to place undue reliance on these forward-looking statements. Except as required by law, the Company assumes no obligation to update these forward-looking statements publicly, or to update the reasons actual results could differ materially from those anticipated in the forward-looking statements, even if new information becomes available in the future. If the Company updates one or more forward-looking statements, no inference should be drawn that it will or will not make additional updates with respect to those or other forward-looking statements.

This press release has been prepared in both French and English. In the event of any differences between the two texts, the French language version shall supersede.