Medicinal composition usable for preventing and/or treating blood coagulation factor IX abnormality, comprising multispecific antigen binding molecule replacing function of blood coagulation factor VIII

A method of treating a blood coagulation factor IX disorder in a patient who is not concurrently being treated with a factor IX formulation, the method comprising administering to the patient a pharmaceutical composition comprising a bispecific antibody that recognizes (a) blood coagulation factor IX and/or activated blood coagulation factor IX, and (b) blood coagulation factor X, and that functionally substitutes for blood coagulation factor VIII,

• wherein the bispecific antibody comprises a first polypeptide and a third polypeptide that form a pair and a second polypeptide and a fourth polypeptide that form a pair,
• wherein the first polypeptide consists of an H chain comprising H chain CDR 1, 2, and 3 amino acid sequences of SEQ ID NOs:
• 1, 2, and 3, respectively;
• the second polypeptide consists of an H chain comprising H chain CDR 1, 2, and 3 amino acid sequences of SEQ ID NOs:
• 4, 5, and 6, respectively;
• and the third and fourth polypeptides each consist of a common L chain comprising L chain CDR 1, 2, and 3 amino acid sequences of SEQ ID NOs:
• 7, 8, and 9, respectively,
• wherein neither blood coagulation factor IX nor activated blood coagulation factor IX is co-administered with the bispecific antibody, and
• wherein the patient does not completely lack blood coagulation factor IX activity.