Balancing the benefits and risks of rebalancing coagulation in haemophilia

Rebalancing agents represent a novel therapeutic class in haemophilia, designed to restore the deficient thrombin generation that underlies bleeding. Unlike factor replacement or factor VIII mimetic therapies, rebalancing agents act by downregulating natural anticoagulants. By partially inhibiting these physiological brakes of coagulation, they induce a controlled and reversible procoagulant shift. These agents have shown clinically meaningful reductions in bleeding rates across both haemophilia A and B, including in patients with inhibitors. However, their therapeutic window appears narrow; excessive thrombin generation might lead to thrombosis, whereas conservative dosing could fail to fully prevent bleeding. The optimal balance between efficacy and safety, therefore, remains to be defined. Current or potential future indications include haemophilia B with inhibitors, young children in whom venous access limits prophylaxis, patients with suboptimal bleed control despite standard therapies, or those with other bleeding disorders. Tissue factor pathway inhibitor inhibition might confer specific benefits in reducing joint bleeding and synovitis, due to its local tissue expression. Overall, rebalancing agents broaden the therapeutic landscape but require judicious patient selection, individualised monitoring, and continued evaluation of their long-term safety and clinical positioning.