Efficacy and Safety of Alpha1-Proteinase Inhibitor (Human), Modified Process (Alpha-1 MP) in Subjects With Pulmonary Emphysema Due to Alpha1 Antitrypsin Deficiency (AATD)

Inclusion Criteria: * Have a documented total alpha1-PI serum level \< 11 µM. * Have a diagnosis of congenital AATD with an allelic combination of ZZ, SZ, Z(null), (null)(null), S(null), or "at-risk" alleles. * At the Screening (Week -3) Visit, have a post-bronchodilator forced expiratory volume in 1 second (FEV1) ≥ 30% and \< 80% of predicted and FEV1/forced vital capacity (FVC) \< 70% (Global Initiative for Chronic Obstructive Lung Disease \[GOLD\] stage II or III). * Have a carbon monoxide diffusing capacity (DLCO) ≤ 60% of predicted (corrected for HgB) within the past 2 years OR evidence of pulmonary emphysema on CT scan within the past 2 years per the Investigator's judgment. * Have clinical evidence of pulmonary emphysema per the Investigator's judgment. Exclusion Criteria: * Has received alpha1-PI augmentation therapy for more than 1 month within the six months prior to the Screening Visit. * Has received alpha1-PI augmentation therapy within one month of the Screening Visit. * Has had a chronic obstructive pulmonary disease (COPD) exacerbation within the 5 weeks prior to the Screening Visit or during the Screening Phase. * Unable to physically (e.g., unable to fit inside the CT scanner) or mentally (e.g., claustrophobic) undergo a CT scan. * History of lung or liver transplant. * Any lung surgery during the past 2 years (excluding lung biopsy). * On the waiting list for lung surgery, including lung transplant. * Smoking during the past 12 months or a positive urine cotinine test at screening that is due to smoking. Maybe on Nicotine replacement, including vapor cigarettes. * History of anaphylaxis or severe systemic response to any plasma-derived alpha1-PI preparation or other blood product(s). * Use of systemic steroids above a stable dose equivalent to 5 mg/day prednisone (i.e., 10 mg every 2 days) within the 5 weeks prior to the Screening Visit (inhaled steroids are not considered systemic steroids) or during the Screening Phase. * Use of systemic or aerosolized antibiotics for a COPD exacerbation within the 5 weeks prior to the Screening Visit or during the Screening Phase. * Known selective or severe Immunoglobulin A (IgA) deficiency.