Antithrombin Concentrate in Congenital and Acquired Antithrombin Deficiency: Two Phase 3 Studies

Introduction Antithrombin concentrates are used to treat patients with inherited (congenital) or acquired antithrombin deficiency. Acquired deficiency can result from conditions such as disseminated intravascular coagulopathy, prior heparin therapy, or major surgeries such as cardiac surgery with cardiopulmonary bypass (CPB). Several commercial antithrombin concentrates with different compositions and purities are available for use. Octapharma’s plasma-derived, highly purified, double virus-inactivated, lyophilized antithrombin concentrate is established as safe and effective for use in many European countries; however, it is not yet approved for the treatment of congenital or acquired antithrombin deficiency in the United States (US). Production of this antithrombin concentrate involves two independent pathogen inactivation steps and a specific cleansing step to remove denatured antithrombin. Due to its high purity, the final product does not require heparin as a stabiliser. Two prospective Phase 3 studies, ATN-106 and ATN-108, aim to provide additional evidence on the efficacy and safety of this antithrombin concentrate. Method ATN-106 (NCT04918173) is a multicentre, open-label, uncontrolled study to assess the efficacy, safety, and pharmacokinetics of Octapharma’s antithrombin concentrate in patients with congenital antithrombin deficiency undergoing surgery or childbirth. ATN-108 (NCT06096116) is a multicentre, double-blind, placebo-controlled study in heparin-resistant patients with acquired antithrombin deficiency scheduled for cardiac surgery necessitating CPB. The protocol for ATN-108 was recently amended to include a revised dosing regimen and additional study sites/regions. ATN-106 and ATN-108 are funded by Octapharma and conducted according to the ethical principles outlined in the Declaration of Helsinki. Patient consent is required for both studies. Further details of ATN-106 and ATN-108 are shown in [ Figure 1 ] [ 2 ], respectively. Fig. 1