Hemophilia A is a medical condition where blood clotting is easily reduced, causing the patient to bleed severely, even from the slightest injuries. Currently, the only way to care for patients with Hemophilia A is by regular infusions of FVIII protein into their bloodstream.
A new adeno-associated viral (AAV) gene therapy that helped to enable hemophiliac patients to express the FVII protein in their livers. One study trialed 18 hemophilia A males, between ages 18 to 52, that were infused with four different doses of SPK-8011. Most of these participants also took steroids because previous research showed that many patients developed an immunity to the AAV vector and eventually eliminating it and in turn, expressed FVII.
16 out of the 18 patients were able to maintain full FVIII expression for the entirety of the trial and 12 of those patients were observed for more than two years and had no decrease in FVIII activity.
Overall, the patients had a 91.5% success rate in reduction in excessively bleeding. However 2 of the patients did lose the expression within a year. This proves that the steroids aren't guaranteed to prevent a loss of expression, however, there are no major safety concerns throughout the study.