Plain language summary of efanesoctocog alfa for patients with severe hemophilia A

This is a plain language summary of a clinical research study called XTEND-1. The study looked into how safe and effective a medicine called efanesoctocog alfa is for people with severe hemophilia A. Hemophilia A is a genetic condition in which the body does not produce enough or makes dysfunctional clotting factor VIII (eight) – a protein that is essential for blood clotting. People with hemophilia A are prone to dangerous bleeding, particularly internally and into their joints and muscles. The XTEND-1 study compared two ways of using the medication to treat bleeding episodes: (1) injecting it once a week for 12 months as a prophylaxis (regular preventative) treatment, or (2) injecting it as needed for 6 months, followed by weekly prophylaxis treatment for a further 6 months. People who had prophylaxis treatment with efanesoctocog alfa injections for one year saw a significant reduction in the amount of bleeding they experienced compared to their pre-study prophylaxis treatment. The effects of the treatment also lasted longer, with higher factor VIII levels for longer, than previous prophylaxis treatment and less frequent injections were needed. There was a significant reduction in the amount of bleeding in people taking once-weekly prophylaxis treatment compared to ‘as needed’ treatment.