AveXis to Advance Gene Therapy Program Initiated by the Rett Syndrome Research Trust

TRUMBULL, CT — The Rett Syndrome Research Trust (RSRT) is excited to announce that AveXis, Inc., has committed to advance a gene therapy candidate for Rett Syndrome into human clinical trials. AveXis, a pioneering clinical-stage gene therapy company, has already advanced a transformative gene therapy treatment for spinal muscular atrophy Type 1, a devastating disease that strikes infants and kills in toddlerhood. Remarkably, in a Phase 1 clinical trial, infants treated with the gene therapy achieved developmental milestones, including the ability to sit unassisted, talk and walk in some cases, – achievements never seen in untreated babies with the disease. It is our shared belief that gene therapy, the introduction of healthy MECP2 genes to compensate for the mutated ones, may also produce benefits for individuals with Rett Syndrome.

This milestone represents the culmination of research originating in 2010 when RSRT funded the collaboration between Dr. Gail Mandel and Dr. Brian Kaspar, the now scientific founder and Chief Scientific Officer of AveXis, to explore the potential of gene therapy for the treatment of Rett Syndrome. Encouraged by the results of that collaboration, in 2014 RSRT conceived of, recruited the scientists for and funded the Gene Therapy Consortium to definitively evaluate the feasibility of gene therapy as a treatment for Rett Syndrome.

The Consortium scientists, Stuart Cobb, Steve Gray, Brian Kaspar and Gail Mandel, exceeded our expectations by developing a gene therapy product candidate with impressive efficacy, safety and delivery characteristics. Importantly, therapeutic benefits in the mouse models are much greater than that of any drug ever tested for Rett Syndrome.

Adrian Bird’s 2007 reversal study showing that symptoms in mice can be dramatically reversed suggests that a diagnosis of Rett need not translate to lifelong disability. While gene therapy seems an obvious approach for any of the numerous single gene disorders, the quality of the data generated by the Consortium was an essential factor in AveXis’ decision to prioritize development of a gene therapy for Rett Syndrome.

“RSRT recognized early on that the gene therapy approach would move forward only if we aggressively championed
it. We brought together scientists with strong track records of success and provided them with the financial support and infrastructure to work effectively and efficiently. Our strategy worked and I am thrilled that AveXis, a leader in gene therapy, is now taking this work forward at an industry scale. I am beyond grateful to the many Rett families who believe in our vision and to the generosity of their networks that make our vital work possible,” said Monica Coenraads, Executive Director of RSRT and mother to a young woman with Rett Syndrome.

“As was made clear in RSRT’s recently launched strategic research plan, Roadmap to a Cure, our mission is a cure for Rett Syndrome. Today’s announcement is a huge step forward towards our goal. By addressing the core cause of Rett, gene therapy has the potential to be a life-changer. We have complete confidence in the expertise and leadership of the AveXis team and will continue to provide our full support as this program moves forward,” said Randall Carpenter, Chief Scientific Officer, RSRT.

“Without RSRT championing gene therapy for the treatment of Rett Syndrome, we would not be where we are preclinically in our understanding of the potential for gene therapy to treat this devastating disease,” said Brian Kaspar, Chief Scientific Officer of AveXis. “Bringing our expertise and focus on rare monogenic diseases, we are excited by the possibility that gene therapy may address the needs of individuals with Rett Syndrome.”