Study of IV Human Plasma-derived C1 Esterase Inhibitor Concentrate in Patients With Congenital C1-INH Deficiency for Treatment and Pre-procedure Preventing of Acute Hereditary Angioedema Attacks

Inclusion Criteria:

1. Is at least 18 years of age (applicable for 1st study phase) or is at least 2 yearsof age (applicable for 2nd study phase)

2. Has confirmed diagnosis of HAE type I or II

3. Has had at least 3 moderate or severe HAE attacks (excluding extremity attacks) inthe last 3 months before the Screening Visit. For participants ≥2 and ≤12 years ofage, has had at least 1 moderate or severe HAE attack (excluding extremity attacks)in the last 6 months before Screening Visit

4. Has a documented congenital C1-INH functional activity <50% with or without C1-INHdeficiency and C4 antigen level below the laboratory reference range

5. Participant or the participant's legally authorized representative(s) has signedinformed consent (as required by local law), with the assent of participants legallycapable of providing it, as applicable

6. States willingness to comply with all study procedures and availability for theduration of the study

7. If the participant is of childbearing potential (CBP), has a negative pregnancy testand must have been using a highly effective method of contraception and continue todo so until at least 2 weeks after their last dose (for both blinded and open-labeldoses of IMP). Not of CBP is defined as surgically sterilized (hysterectomy,bilateral oophorectomy) or who are postmenopausal (defined as women with no mensesfor 12 months without an alternative medical cause). Highly effective methods ofcontraception:

• Combined hormonal contraception (estrogens and progesterone) methods such asoral, implantable, intravaginal, injectable, or transdermal contraceptives at astable dose for a minimum of 1 full cycle (hormonal contraceptives must inhibitovulation) and for at least 4 weeks before screening

• Progesterone only hormonal contraception associated with inhibition ofovulation (oral, injectable, implantable)

• Intrauterine device

• Intrauterine hormone-releasing system inserted at least 4 weeks beforescreening

• Bilateral tubal ligation/occlusion or vasectomized partner (with surgicalsuccess confirmed by medical assessment) OR Agrees to abstain from heterosexualintercourse during study participation and to use a highly effectivecontraceptive (as described above) as backup if they become sexually activeduring the study. Abstinence is only acceptable if this is the participant'susual lifestyle. Periodic abstinence (calendar, symptothermal, post-ovulationmethods), withdrawal (coitus interruptus), spermicides only, and lactationalamenorrhea method are not acceptable methods of contraception

• Note: If a participant of CBP has a positive or suspected positive urinepregnancy test within 72 hours prior to treatment, a serum pregnancy test willbe required

• Male participants must not plan to father a child or donate sperm for 90 daysafter their last dose of study drug (for both blinded and open-label doses ofthe IMP). However, there are no official contraception requirements for maleparticipants during the study.

Inclusion Criteria for IMP Dosing for QAT:

1. Has confirmed QAT per definition criteria

2. Has a swelling episode that is new and not the continuation of a previous HAE attack

Exclusion Criteria:

1. Has a history of clinically relevant antibody development against C1-INH

2. Has a medical history consistent with Type 3 HAE (i.e., onset at age above 40 year,no family history, no known HAE mutation, low C1q level in plasma)

3. Has a history of allergic reaction to C1-INH or other blood/plasma product

4. Has a history of B-cell malignancy that was unresolved in the past 5 years

5. Has a narcotic and/or alcoholic addiction

6. Has participated in any other investigational drug evaluation within 30 days beforescreening

7. Is pregnant or breastfeeding

8. Has any clinically significant medical or psychiatric condition that, in theinvestigator's opinion would interfere with the participant's ability to participatein the study

9. Has a history of thromboembolic events (TEEs), myocardial infarction, unstableangina pectoris, critical aortic stenosis, cerebrovascular accident, transientischemic attack, severe peripheral vascular disease, or disseminated intravascularcoagulation within one year before screening

10. (applicable until IDMC review of the interim preliminary safety and efficacy data):has clinically significant derangement in measurements of cardiovascular status (i.e. uncontrolled arterial hypertension, cardiac insufficiency New York HeartAssociation (NYHA) class III-IV), pulmonary status (i.e., COPD GOLD classification 3and 4, severe asthma) and renal status (i.e., eGFR below 90 ml/min per 1.73 m2)

Exclusion Criteria for IMP Dosing for QAT:

1. Has received blood or a blood product for prophylactic or acute treatment with anyC1-INH (Berinert®, Cinryze®, HAEgarda®, Ruconest®, etc.), non-biological bradykininand kallikrein pathway inhibitors (e.g., ecallantide, icatibant, berotralstat), ortreatment with tranexamic acid within 14 days before dosing with the IMP (or is notwilling to abstain from these medications throughout the study)

2. started or changed hormone replacement therapy or selective estrogen receptormodulators (e.g., tamoxifen) within 14 days before IMP dosing

3. Started or changed androgen therapy (e.g. testosterone, dehydro-epiandrosterone/androstenedione, oxandrolone, danazol, stanozolol) within 14 daysbefore IMP dosing or is not willing to maintain a stable dose throughout the study

4. Started or changed the dose of monoclonal antibodies e.g. lanadelumab within 11weeks before dosing or not willing to maintain a stable dose throughout the study

5. Has used narcotic pain medications or non-opioid analgesics within 7 days before IMPdosing for a QAT

6. Has received OCTA-C1-INH within 14 days before IMP dosing

Exclusion Criteria for IMP Dosing for PK:

1. Has received blood or a blood product for prophylactic or acute treatment with anyC1-INH (Berinert®, Cinryze®, HAEgarda®, Ruconest®, etc.), non-biological bradykininand kallikrein pathway inhibitors (e.g., ecallantide, icatibant, berotralstat), ortreatment with tranexamic acid within 14 days before dosing with the IMP (or is notwilling to abstain from these medications throughout the study)

2. Is receiving hormone replacement therapy or selective estrogen receptor modulators (e.g., tamoxifen) and has had their dose changed within 14 days before IMP dosing

3. Is receiving or has received androgen therapy (e.g., testosterone,dehydroepiandrosterone/androstenedione, oxandrolone, danazol, stanozolol) IN ANYDOSE within 14 days before dosing

4. Started or changed the dose of monoclonal antibodies e.g lanadelumab within 11 weeksbefore dosing or not willing to maintain a stable dose throughout the study

5. Has used narcotic pain medications or non-opioid analgesics within 7 days before IMPdosing

6. Has received IMP within 14 days before IMP dosing

7. Has planned dental, medical, or surgical procedures during the PK Period that willrequire pre-procedural prevention