This study is evaluating an investigational drug, eptacog beta (EB), for the treatment and prevention of acute bleeding episodes in people with Glanzmann Thrombasthenia, a rare inherited bleeding disorder. Eptacog beta (EB) is not currently approved by the U.S. Food and Drug Administration (FDA) for this condition. The study will assess the effectiveness and safety of eptacog beta (EB) when used to treat serious bleeding events, and in an optional phase, when used routinely to prevent bleeding. During the first three (3) months, participants will manage any bleeding episodes with their standard treatment (e.g., factor products or platelet transfusions). After this initial period, they will use the study drug to treat serious bleeding events. Participants will have approximately 4 to 5 visits with their hematologist over the 9-month study period. They will also be asked to complete a diary documenting bleeding episodes and treatments, and to answer questions about how bleeding affects their daily life. Blood samples will be collected to monitor their condition and any potential side effects of the study drug. At the end of the main study, participants will have the option to enter an optional extension phase, where they will receive routine intravenous infusions of the study drug 2 to 3 times per week for 6 months to help prevent future bleeding episodes and complications.