Primary Objective:

To evaluate the efficacy of recombinant human C1 inhibitor (rhC1INH) in the prophylaxis of angioedema attacks in patients with HAE

Secondary Objective:

To evaluate the safety and immunogenicity of recombinant human C1 inhibitor (rhC1INH) in the prophylaxis of angioedema attacks in patients with HAE

Study Design:

This is a multi-center, randomized, double-blind, placebo-controlled, 3-period crossover study of rhC1INH in prophylaxis of angioedema attacks in patients with HAE.

Medical screening (clinical and laboratory parameters) will be performed and patient medical history specific to HAE attacks will be collected to assess eligibility. Each patient will receive three 4 week periods of treatment twice weekly.

Inclusion Criteria:

Patients fulfilling the following criteria at Screening are eligible for participation in the study:

1. Age 13 years or older
2. Laboratory confirmed diagnosis of HAE
3. A history of frequent HAE attacks (at least 4 attacks per month across a minimum of 3 consecutive months).
4. Female patients of childbearing potential who are sexually active must be willing to use an acceptable form of contraception.
5. Provided written informed consent (and written assent for minors)
6. Willingness and ability to comply with all protocol procedures

Exclusion Criteria:

Patients who meet any of the following criteria at Screening are to be excluded from study participation:

1. Patients with medical history of allergy to rabbits or rabbit-derived products (including rhC1INH)
2. Diagnosis of acquired angioedema (AAE)
3. Patients who are pregnant, or breastfeeding, or are currently intending to become pregnant
4. Treatment with any investigational drug in the past 30 days
5. Patients with any condition or treatment that, in the opinion of the Investigator, might interfere with the evaluation of study objectives
6. Patients currently treated with angiotensin-converting enzyme (ACE) inhibitors

Population is intention to treat (ITT) population

20 weeks