Vivet Therapeutics Wilson Disease Update April 2024

Dear members of the Wilson disease community,

We are pleased to update you on the progress of GATEWAY, the first gene therapy clinical study evaluating the effects of Vivet’s investigational therapy VTX-801, which is intended to treat patients living with Wilson disease. The GATEWAY study is ongoing, actively enrolling, and is taking place across several locations across the US, UK, Germany and Denmark. Each participant receives a single intravenous infusion of VTX-801 and is then followed-up for 5 years to evaluate the safety and the efficacy of the product. Three consecutive groups of patients receive an increasing dose level of VTX-801, the first group receiving the lowest dose to be studied. Early April, we announced that dosing of the first group of patients (lower dose) has been completed, and that the first patient of the second group has been dosed (intermediate dose); dosing of the second group followed the favorable opinion of an independent Safety Committee composed of four Wilson disease experts who reviewed the promising data collected so far in the first patient group.

Dr. Michael Schilsky, Principal Investigator at the Yale clinical trial site for GATEWAY, commented, “Evaluation of VTX-801 as a treatment option for Wilson disease is making good progress with no detected serious adverse events in the first dose, Cohort 1 patients. Existing treatments for Wilson disease are lifelong and adherence to daily treatment often requiring multiple medication doses aimed at removing excess copper from the body is a serious problem. Additionally, current treatments are not universally effective and can cause adverse side effects in some patients. VTX-801 is designed to restore the normal copper metabolism by providing an engineered, fully functional version of the ATP7B copper transporter gene in the liver, and gives hope to the possibility of eliminating the need for additional medical therapy for this disorder. Early, encouraging data from Cohort 1 has shown detectable vector transduction and transgene expression with early signs of improvement in liver function and histology. We look forward to moving this groundbreaking program further through the GATEWAY study and future clinical trials as we seek to demonstrate its transformative potential for patients with Wilson disease.”

Please visit the GATEWAY clinical trial site for more information about the study. Additional questions can be sent to patients@vivet-therapeutics.com.