Efficacy of Atenativ in Patients With Congenital Antithrombin Deficiency Undergoing Surgery or Delivery

Inclusion Criteria:

1. Adult male or female patients ≥18 and ≤80 years of age. Solely in the US, 4 male orfemale patients between ≥12 and <17 years of age will be enrolled into the PK phase,and subsequently in the treatment phase, if applicable

2. Documented congenital antithrombin deficiency, defined by plasma activity level ofantithrombin ≤60% from medical history

3. Personal or family history of TEs or TEEs (except for PK patients)

4. For the Treatment Phase: either a) non-pregnant surgical patients scheduled forelective surgical procedure(s) known to be associated with a high risk foroccurrence of TEs or TEEs, or b) pregnant patients of at least 27 weeks gestationalage who are scheduled for caesarean section or delivery

5. For female patients of childbearing potential entering the PK Phase who are notknown to be pregnant, and for female surgical patients of childbearing potentialentering the Treatment Phase for any procedure other than caesarean section ordelivery, a negative urine pregnancy test at screening and at baseline

6. Patient has provided informed consent

Exclusion Criteria:

1. Requires emergency surgery or emergency caesarean section

2. Has undergone surgery within the last 6 weeks

3. History or suspicion of another hereditary thrombophilic disorder other thanantithrombin deficiency (e.g., activated protein C [APC] resistance/Factor V Leiden,Protein S or C deficiency, prothrombin gene mutation [G20210A], or acquired [lupusanticoagulant] thrombophilic disorder)

4. Malignancies, renal failure (patients on renal replacement therapy), or severe liverdisease (aspartate aminotransferase [ASAT] >5 times the upper limit of normal)

5. Body mass index >40 kg/m2 (for non-pregnant patients, only)

6. Known hypersensitivity or allergic reaction to antithrombin or any of the excipientsin Atenativ

7. History of anaphylactic reaction(s) to blood or blood components

8. Refusal to receive transfusion of blood-derived products

9. Administration of any antithrombin concentrate or antithrombin-containing bloodproduct within 14 days of either of the two phases of the study

10. Prior diagnosis of heparin-induced thrombocytopenia

11. TE or TEE within the last 6 months

12. Female patients who are nursing at the time of screening*

13. Have participated in another investigational study within the last 30 days

14. Persons dependent on the sponsor, the investigator or the centre of investigation

15. Persons placed in an institution by administrative or judicial order

• criterion does not include female patients who plan to breastfeed after givingbirth