Anti-Severe Acute Respiratory Syndrome Coronavirus 2 Hyperimmune Immunoglobulin Demonstrates Potent Neutralization and Antibody-Dependent Cellular Cytotoxicity and Phagocytosis Through N and S Proteins.

BACKGROUND: Although coronavirus disease 2019 (COVID-19) vaccinations have provided a significant reduction in infections, effective COVID-19 treatments remain an urgent need. METHODS: Functional characterization of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) hyperimmune immunoglobulin (hIG) from human convalescent plasma was performed by different virus neutralization methodologies (plaque reduction, virus-induced cytotoxicity, median tissue culture infectious dose [TCID50] reduction, and immunofluorimetry) at different laboratories using geographically different SARS-CoV-2 isolates (USA [1], Italy [1], and Spain [2]; 2 containing the D614G mutation). Neutralization capacity against the original Wuhan SARS-CoV-2 strain and variants (D614G mutant, B.1.1.7, P.1, and B.1.351) was evaluated using a pseudovirus expressing the corresponding spike (S) protein. Antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) was also evaluated. RESULTS: All SARS-CoV-2 isolates were potently neutralized by hIG as shown by all 4 methodologies. Wild-type SARS-CoV-2 and variants were effectively neutralized using the pseudovirus. The hIG (IgG type) induced ADCC and ADCP against SARS-CoV-2 N and S proteins but not E protein. Very low concentrations (25-100 µg IgG/mL) were required. A potent effect was triggered by antibodies in hIG solutions against the SARS-CoV-2 S and N proteins. CONCLUSIONS: Beyond neutralization, IgG Fc-dependent pathways may play a role in combatting SARS-CoV-2 infections using COVID-19 hIG. This could be especially relevant for the treatment of more neutralization-resistant SARS-CoV-2 variants.

Production of anti-SARS-CoV-2 hyperimmune globulin from convalescent plasma.

BACKGROUND: In late 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus emerged in China and quickly spread into a worldwide pandemic. Prior to the development of specific drug therapies or a vaccine, more immediately available treatments were sought including convalescent plasma. A potential improvement from convalescent plasma could be the preparation of anti-SARS-CoV-2 hyperimmune globulin (hIVIG). STUDY DESIGN AND METHODS: Convalescent plasma was collected from an existing network of plasma donation centers. A caprylate/chromatography purification process was used to manufacture hIVIG. Initial batches of hIVIG were manufactured in a versatile, small-scale facility designed and built to rapidly address emerging infectious diseases. RESULTS: Processing convalescent plasma into hIVIG resulted in a highly purified immunoglobulin G (IgG) product with more concentrated neutralizing antibody activity. hIVIG will allow for the administration of greater antibody activity per unit of volume with decreased potential for several adverse events associated with plasma administration. IgG concentration and IgG specific to SARS-CoV-2 were increased over 10-fold from convalescent plasma to the final product. Normalized enzyme-linked immunosorbent assay activity (per mg/ml IgG) was maintained throughout the process. Protein content in these final product batches was 100% IgG, consisting of 98% monomer and dimer forms. Potentially hazardous proteins (IgM, IgA, and anti-A, anti-B, and anti-D) were reduced to minimal levels. CONCLUSIONS: Multiple batches of anti-SARS-CoV-2 hIVIG that met regulatory requirements were manufactured from human convalescent plasma. The first clinical study in which the hIVIG will be evaluated will be Inpatient Treatment with Anti-Coronavirus Immunoglobulin (ITAC) [NCT04546581].

Plasma Donors in the Southwestern United States Positively Contribute to the Diverse Therapeutic Antibody Profile of Immune Globulin Products.

Human-plasma-derived immune globulin (IG) is used in augmentation therapy to provide protective levels of antibodies to patients with primary immune deficiency diseases (PIDD) and for prophylaxis against infectious diseases. To maintain the breadth of antibodies necessary for clinical protection, it is important to understand regional patterns of antibody seroprevalence in source plasma from which IG products are manufactured. In this study, source plasma from donation centers in various locations of the Southwestern quarter of the United States was surveyed for antibody titers to hepatitis A virus (HAV), measles virus (MeV), and cytomegalovirus (CMV). A broad range of anti-HAV Ig plasma titers was observed among these centers, with some centers exhibiting 3-5 times the titers of the others. Minor to no differences were observed for levels of anti-MeV and anti-CMV, respectively. Importantly, elevated anti-HAV Ig titers were broadly observed across plasma units obtained from the centers exhibiting high titers, indicative of a potential regional phenomenon among donors as opposed to few donors with singularly high titers. Plasma from these high-titer centers conferred significantly greater neutralization against HAV in vitro. The outcomes of this study give a glimpse of the antibody diversity inherent in human plasma used to manufacture IG products..

Measles antibody trough levels after treatment with immunoglobulin products and predicted levels assuming lower measles antibody specifications.

BACKGROUND: Widespread vaccination against measles has resulted in decreasing measles antibody levels in human immune globulin (IG) products. As levels continue to decline, it needs to be determined whether the release specifications for measles antibody levels in IG products can be lowered and still provide protection against infection for patients who receive IG treatment for primary immunodeficiency disease. STUDY DESIGN AND METHODS: Trough level measles neutralizing antibodies were measured in 10 pediatric patients with primary immunodeficiency disease (ages 2-16) treated with IG administered both by intravenous and subcutaneous infusion. The results were used to model worst-case (lowest) serum measles antibody levels in two cases: 1) the current case with intravenous dosage at 300 mg/kg at a measles antibody level of 0.48× Center for Biologics Evaluation and Research Reference 176 and 2) a future case with intravenous dosage at 400 mg/kg and 0.30× Center for Biologics Evaluation and Research Reference 176. RESULTS: Serum trough measles neutralizing antibody levels were an average of 11-fold or greater above minimum protective levels for immunocompetent individuals of 0.12 IU/mL in both the intravenous and subcutaneous phases of the study. Modeling using both the current worst-case dose and future case shows average levels for IG intravenous/subcutaneous infusion of 3.9/4.8- and 3.2/4.0-fold above 0.12 IU/mL for the two cases, respectively. CONCLUSION: Lowering the measles antibody level specification to 0.30× Center for Biologics Evaluation and Research Reference 176 in IG products will still provide trough serum antibody levels against measles infection of greater than 0.12 IU/mL when dosed at 400 mg/kg or higher.

Safety and neutralizing rabies antibody in healthy subjects given a single dose of rabies immune globulin caprylate/chromatography purified.

BACKGROUND: Rabies immune globulin (RIG) and vaccination series are necessary for postexposure prophylaxis. A new formulation of RIG (human) purified by caprylate/chromatography (RIG-C) was evaluated. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02139657. MATERIALS AND METHODS: This open-label, single-arm study in healthy subjects evaluated neutralizing rabies antibody concentrations produced from a single 20 IU/kg intramuscular (IM) dose of RIG-C as measured by rapid fluorescent focus inhibition test (50% neutralization endpoint) 1-hour postdose and on days 1, 2, 4, 6, 8, 10, 14, 18, and 21. RESULTS: Twelve subjects were enrolled into the study. No discontinuations, serious adverse events (AEs), or treatment-emergent clinically significant changes in laboratory parameters were observed. All AEs resolved and were mild except 1 moderate AE of oropharyngeal pain. Injection site pain (4 subjects) was most commonly reported. RIG-C produced a rapid increase in neutralizing rabies antibody: mean value 0.113 IU/mL at 24 hours after IM injection, peak on day 4 (0.132 IU/mL), persisting through day 21 (0.116 IU/mL). The mean reciprocal titer was 11.5 by day 2; the peak value of 12.1 was achieved on day 4; and a mean value ≥10.6 was maintained through day 21. CONCLUSION: RIG-C was well tolerated and provided neutralizing rabies antibodies, which combined with vaccine series after rabies exposure, should result in effective prophylaxis per World Health Organization/Centers for Disease Control and Prevention guidelines.