The purpose of this study is to examine the safety, tolerability and the way the body handles various single and multiple doses of ARC19499 in patients with hemophilia.

Inclusion Criteria:

Adult male patients ≥18 to ≤75 years of age.

• Hemophilia of any type or severity.
• Patients who are negative for hepatitis B surface antigen (HBsAg), and human immunodeficiency virus (HIV) I and II antibody tests at screening.
• Male patients who, with their partners, are willing to use 2 effective, methods of contraception (i.e., for both self and partner) throughout the study and for at least 3 months after discontinuation of study drug treatment.
• All patients must be capable of understanding and complying with the protocol and must have signed the informed consent document.

Exclusion Criteria:

• Female patients;
• If on a prophylactic coagulation factor concentrate regimen, inability or unwillingness to discontinue prophylaxis during participation in this study.
• Existence of other co-existing bleeding disorder (e.g., von Willebrand Disease).
• Medical history of venous or arterial thromboembolism.
• Scheduled for elective surgical procedure during the conduct of this study.
• Use of an investigational drug within 30 days of study entry.
• Transaminase values > 3 x upper limit of normal (ULN) at time of screening.
• Haemoglobin <12.0 g/dL.
• Participants who, in the opinion of the Investigator, have a significant infection or known inflammatory process on screening.
• Participants who have a clinically relevant history or presence of respiratory, gastrointestinal, renal, hepatic, lymphatic, neurological, cardiovascular, psychiatric, musculoskeletal, genitourinary, immunological, dermatological, connective tissue diseases or disorders.
• Any medical condition the investigator believes would place the patient at increased risk as a result of participation in the study e.g. history of thromboembolic disease or stroke.
• Any medication the investigator considers may increase the risk of adverse effects during the study.