This study is testing a new drug called eptacog beta (EB) to help people with Glanzmann Thrombasthenia, a rare bleeding disorder where blood doesn't clot well. Eptacog beta is not yet approved by the FDA, so it's considered "investigational." For the first 3 months, participants will use their usual treatments for bleeding. After that, they'll use eptacog beta to manage serious bleeds over 6 months. They also have the option to continue for another 6 months to help prevent bleeds.

Participants will have 4 to 5 visits with a doctor over 9 months. They'll keep a diary about their bleeding and how it affects their life, and they'll give blood samples to check for any side effects.

• The main study lasts 9 months, with an optional 6-month extension.
• Participants will visit the doctor 4 to 5 times and keep a diary.
• They will receive treatment for serious bleeding events and possibly routine prevention.