David Rees, MA, MBBS, FRCP, FRCPath, FRCPCH, King’s College Hospital, London, UK, discusses the future of gene therapies in treating sickle cell disease (SCD). Prof. Rees outlines the findings of a trial (NCT04293185) evaluating gene therapy with a lentiviral vector, which was stopped due to development of myelodysplastic syndrome (MDS) in patients. Additional approaches involve attempts to increase fetal hemoglobin (HbF) levels or knockdown inflammatory markers, but these approaches fail to completely cure SCD. Future developments may involve in vivo gene therapies that can correct the sickle cell mutation. This interview took place at the 2021 British Society for Haematology Annual Scientific Meeting.