The objectives of the study were:

1. To assess the safety and tolerability of escalating doses of CINRYZE.
2. To assess the effect of an escalating dose algorithm for CINRYZE on hereditary angioedema (HAE) attack rates.
3. To assess the immunogenicity of CINRYZE.

Qualifying subjects entered a 3-step dose escalation algorithm:

• Step 1: 1500 Units twice per week (starting dosing regimen for all subjects in the study)
• Step 2: 2000 Units twice per week
• Step 3: 2500 Units twice per week

Each step consisted of 12 weeks of safety monitoring, followed by calculation of average monthly angioedema attack rate based on subject reports of angioedema symptoms (regardless of intensity) and actual duration of therapy for that step.

If a subject was deemed a "success" at a given step and the investigator and medical monitor determined that it was safe for the subject to continue on that dose, the subject entered a 3 month follow-up period at that dose level with continued safety monitoring. The subject could not re-enter the study for purposes of dose escalation during the follow-up period.

If a subject was not deemed a "success," the subject initiated the next highest step of the dose escalation algorithm provided that the investigator and medical monitor agreed that dose escalation was appropriate. If at the end of Step 3 (2500 Units), a subject was not deemed a "success," then the Week 12 visit represented study completion and the subject was referred to the physician who manages their HAE care.

Inclusion Criteria:

To be eligible for this protocol, subjects must:

1. Be ≥6 years of age and ≥25 kg body weight.

2. Have a confirmed diagnosis of HAE with a documented history of swelling of the face, extremities, gastrointestinal tract, genitalia, or larynx and a history of at least one of the following:

   • C1 INH gene mutation
   • C4 level below the lower limit of the reference range
   • C1 INH antigen level below the lower limit of the reference range
   • Functional C1 INH level below the lower limit of the reference range
   • Family history of HAE (i.e., grandparent, parent, sibling)

3. Have a history of >1.0 HAE attack per month (average) of any severity during the 3 consecutive months prior to screening while receiving the recommended CINRYZE dosing of 1000 Units every 3 to 4 days via intravenous injection.

4. If an adult, be informed of the nature of the study and provide written informed consent before any study-specific procedures are performed.

   OR

5. If a child, have a parent/legal guardian who is willing and able to provide written informed consent for the child to participate in the study (with assent from the child when appropriate).

Exclusion Criteria:

To be eligible for this protocol, subjects must not:

1. Have, as determined by the investigator and/or the sponsor's medical monitor, any surgical or medical condition that could interfere with the administration of study drug or interpretation of study results.

2. Have a history of abnormal blood clotting or other coagulopathy.

3. Be taking prescription anticoagulant medication.

4. Have a history of allergic reaction to CINRYZE or other blood products.

5. Have participated in any other investigational drug study within the past 30 days (other than CINRYZE protocols).

6. Have received any blood products (other than CINRYZE) within 60 days prior to screening.

7. Have any of the following laboratory values at screening:

   • Hemoglobin <8 g/dL
   • White blood cell count <2 x 10^9/L or >20 x 10^9/L
   • Platelet count <50 x 10^9/L or >400 x 10^9/L
   • Serum aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) >2.0 x the upper limit of normal
   • Blood urea nitrogen and/or creatinine >2.0 x the upper limit of normal

8. Be pregnant or breastfeeding.

12 to 24 weeks at each dose level. Events reported during the 3 month follow-up period are counted with the dose level at which they occurred.

Per Changes in the Planned Analyses:

The clinical presentation of disease manifestations and response to therapy are highly variable among patients with HAE and as such, the efficacy results from this study are presented in this report by individual participant in narrative summaries rather than as summary statistics.

Thus, one outcome measure (Use of rescue therapy and/or other therapy for treatment of HAE symptoms) is not presented.