Pharmacokinetics and Biochemical Efficacy of an α(1)-Proteinase Inhibitor (Aralast NP) in α(1)-Antitrypsin Deficiency: a Cross-Product Retrospective Comparability Analysis

INTRODUCTION: Augmentation therapy with plasma-derived α(1)-proteinase inhibitor (A1PI) products is currently the only approved disease-specific therapy for α(1)-antitrypsin deficiency (AATD), a genetic disorder associated with decreased levels of A1PI. Systemic trough levels of A1PI in plasma or serum are widely accepted as a biochemical efficacy endpoint in clinical trials for A1PI products. METHODS: Retrospective analyses utilizing data from three clinical studies in patients with AATD were conducted to evaluate the pharmacokinetic(s) (PK) and biochemical efficacy comparability of Aralast NP and two other A1PI augmentation therapies, Aralast and Prolastin. All three A1PI products were administered as either single or multiple 60 mg/kg intravenous infusions. PK and biochemical efficacy comparability analyses were conducted by evaluating antigenic and functional A1PI serum or plasma concentration data from each of the three studies. RESULTS: Comparable PK parameters were demonstrated between the three products for antigenic A1PI levels following a single infusion, with baseline-corrected and uncorrected geometric mean ratios for peak and systemic exposure ranging from 89.0% to 99.6%, with 90% confidence intervals within the 80–125% reference interval for bioequivalence. Biochemical efficacy comparability analyses of Aralast and Prolastin after multiple infusions at steady state showed geometric mean ratios for uncorrected and baseline-corrected antigenic and functional A1PI trough concentrations over weeks 8–11, and for individual weeks, that ranged from 75.8% to 106.6%, with the majority of the 90% confidence intervals falling either within the 80–125% interval or in proximity to it. Nonparametric superpositioning at steady state suggested that predicted trough concentrations for Aralast NP were comparable to the observed concentrations for Aralast and Prolastin. CONCLUSION: These retrospective analyses provide robust evidence that Aralast NP has biochemical efficacy and PK comparable to that of Aralast and Prolastin, supporting the use of any of these A1PI products for the treatment of patients with AATD. TRIAL REGISTRATION NUMBERS: ClinicalTrials.gov identifiers, NCT00242385 and NCT00396006.