Biochemical comparison of four commercially available C1 esterase inhibitor concentrates for treatment of hereditary angioedema.

BACKGROUND: For safe and efficacious treatment of hereditary angioedema, C1 esterase inhibitor (C1-INH) concentrates should have high purity and high amounts of functional protein. As no pharmacopoeia requirements exist for C1-INH concentrate lot release, biochemical characteristics as declared by the manufacturers may not be compared directly. This study compared the characteristics and purity profiles of four commercially available C1-INH concentrates. STUDY DESIGN AND METHODS: The analysis included one transgenic (Ruconest) and three plasma-derived (Berinert, Cetor, Cinryze) C1-INH concentrates. C1-INH antigen concentration was determined by nephelometry, total protein (specific activity) with a Bradford assay, purity by size-exclusion chromatography and gel electrophoresis, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was performed. RESULTS: Functionality (inversely proportional to antigen-to-activity ratio) was lowest for Ruconest (1.67), followed by Cetor (1.42), Berinert (1.24), and Cinryze (1.22). Specific activity (U/mg) and purity (%) were highest in Ruconest (12.13; 98.6) and Berinert (11.57; 97.0), followed by Cinryze (10.41; 89.5) and Cetor (9.01; 88.6). Main protein bands were found for all plasma-derived products at approximately 105 kDa, and for Ruconest, at approximately 98 kDa. Additional bands in the plasma-derived products were α1-antichymotrypsin, ceruloplasmin, Factor C3 (Cinryze/Cetor), and immunoglobulin heavy constant mu (Berinert). CONCLUSION: Ruconest has a very high purity profile but is not identical to the human C1-INH protein. Of the plasma-derived products, Berinert has the highest purity profile. The impact of the nontherapeutic proteins identified has not yet been evaluated. For harmonization of the analysis for drug release, we recommend the establishment of regulatory requirements for purity determination and the implementation of threshold levels in C1-INH concentrates.

Pathogen safety of human C1 esterase inhibitor concentrate.

BACKGROUND: Human plasma-derived products--such as C1 esterase inhibitor (C1-INH) concentrate, used to treat hereditary angioedema--carry with them the risk of transmitting blood-borne viruses and, theoretically, prion proteins. To minimize this risk, three complementary approaches are implemented: selection and testing of plasma donations for the absence of pathogenic blood-borne viruses, similarly testing and releasing the plasma pool for fractionation, and ensuring that the manufacturing process includes validated steps for pathogen inactivation and removal. STUDY DESIGN AND METHODS: This article describes the selection of plasma for the production of C1-INH and the studies used to confirm the pathogen reduction capacity of the manufacturing process: three independent virus reduction steps--pasteurization, hydrophobic interaction chromatography (HIC), and virus filtration--and two prion reduction steps. Samples of product intermediates from the manufacturing steps were spiked with a panel of enveloped and nonenveloped viruses and two prion preparations and subjected to a valid scaled-down version of the respective manufacturing steps resulting in the quantification of the pathogen reduction factors. RESULTS: Validation studies demonstrated overall virus reduction factors for all viruses of more than 15 log, considerably exceeding the potential amount of virus present in a plasma pool for fractionation. Prion proteins were also efficiently removed by the manufacturing process, as currently determined in evaluating the prion removal capacity of the ammonium sulfate precipitation and HIC steps. CONCLUSION: The pathogen reduction capacity demonstrated here indicates that the manufacturing process of the C1-INH Berinert is highly effective for reducing enveloped and nonenveloped viruses and prion proteins.