A Research Study Investigating Mim8 in People With Haemophilia A

Inclusion Criteria: Single ascending dose part 1: * Male, aged 18-45 years (both inclusive) at the time of signing informed consent * Considered to be generally healthy based on the medical history, physical examination, and the results of vital signs, electrocardiogram and clinical laboratory tests performed during the screening visit, as judged by the investigator Multiple ascending dose part 2: * Male, aged 12-64 years (both inclusive) at the time of signing informed consent (Germany and Japan have local requirements) * Diagnosis of congenital haemophilia A with FVIII activity below 1% based on medical records Exploratory biomarker cohort: * Male, aged equal to or above 12 years at the time of signing informed consent (Germany and Japan have local requirements) * Diagnosis of congenital haemophilia A with FVIII activity below 1% based on medical recordsv Exclusion Criteria: Part 1: * Factor VIII activity equal to or above 150% at screening * Increased risk of thrombosis, e.g. known history of personal or first degree relative(s) with unprovoked deep vein thrombosis * Any clinical signs or established diagnosis of venous or arterial thromboembolic disease Part 2: * Known congenital or acquired coagulation disorders other than haemophilia A * Increased risk of thrombosis as evaluated by the investigator. E.g. known history of personal or first degree relative(s) with unprovoked deep vein thrombosis with exception of previous catheter-associated thrombosis for which anti-thrombotic treatment is not currently ongoing * Any clinical signs or established diagnosis of venous or arterial thromboembolic disease with exception of previous catheter-associated thrombosis for which anti-thrombotic treatment is not currently ongoing * Advanced atherosclerotic disease (e.g. known history of ischemic heart disease, ischemic stroke) as evaluated by the investigator * Any autoimmune disease that may increase the risk of thrombosis * Receipt of emicizumab or drugs with similar modes of action within 5 half-lives before trial product administration * Ongoing or planned immune tolerance induction therapy Exploratory biomarker cohort: * Known congenital or acquired coagulation disorders other than haemophilia A * Increased risk of thrombosis as evaluated by the investigator. E.g. known history of personal or first degree relative(s) with unprovoked deep vein thrombosis with exception of previous catheter-associated thrombosis for which anti-thrombotic treatment is not currently ongoing * Any clinical signs or established diagnosis of venous or arterial thromboembolic disease with exception of previous catheter-associated thrombosis for which anti-thrombotic treatment is not currently ongoing * Advanced atherosclerotic disease (e.g. known history of ischemic heart disease, ischemic stroke) as evaluated by the investigator * Any autoimmune disease that may increase the risk of thrombosis * Ongoing or planned immune tolerance induction therapy