The critical need for postmarketing surveillance in gene therapy for haemophilia

Introduction: The goal of gene therapy for haemophilia is to alter the clinical phenotype to a milder form or even cure, by increasing endogenous coagulation factor levels through transfer of a functional gene encoding the respective deficient coagulation factor and subsequent transgene expression. Over the past decade, there has been tremendous progress in gene therapy, particularly in use of liver-directed adeno-associated viral vectors, such that several programmes for both haemophilia A and B are in phase 3 trials. With regulatory approval of the first gene therapy product expected as early as mid-2020, there is an urgent need for a mechanism to collect long-term data on safety and variability and durability of efficacy. There will be elements required by regulators for postmarketing surveillance and additional data needed to enhance our understanding of gene therapy outcomes and their impact on the lives of people with haemophilia. Aim: The aim of this manuscript was to describe efforts underway by the American Thrombosis and Hemostasis Network and the World Federation of Hemophilia to collect long-term harmonized data and considerations of the European and US regulatory agencies, which will inform ongoing data collection. Methods: The status of data collection around gene therapy in haemophilia and important outcome measures were obtained by literature review. Each author described elements relevant to the activities of their organization. Conclusion: Support of all stakeholders in gene therapy, providers, patients, industry and regulators, augers successful capture of uniform long-term safety and efficacy data to ensure optimal treatment of people with haemophilia.