ISTH 2023 | AAV-based gene therapy in hemophilia A and B: valoctocogene roxaparvovec & etranacogene dezaparvovec

AAV-based gene therapy now has already approved two studies for clinical use. That is a Roctavian that was approved in August last year and it is Hemgenix that was approved for hemophilia B just in February this year. Both studies are extensively published and the outcomes are very promising with respect to those patients that do no longer need any factor consumption. The main difference between these two studies is that in hemophilia A with Roctavian there is a decline of the expressed factor activity over time. So after about three years there is about the average or the mean factor levels is about one third of the peak level after about one year. So we can expect that after five to eight years those patients may have to go back on a prophylactic regimen. In hemophilia B, it looks more stable with respect to the duration of the factor level expression. So we expect more than ten years stability. A challenge in hemophilia A is a high proportion of patients that have underwent immune suppression because of ALT elevation. And here I’m sure that the protocols for management of ALT elevations and for immune suppression will improve and will facilitate the treatment and will make this easier for the patients in the future. In hemophilia B the immune suppression is much less significant. It’s in about 20% of the patients and for shorter duration. So now the therapy is licensed and will now become part of our treatment portfolio that we have in the respective countries. It will start slowly I think, because we need some experience and also the regulatory environment have to be prepared for these new treatments, but they will become a very promising option for the future.