L-proline-stabilized human IgG: Privigen® 10% for intravenous use and Hizentra® 20% for subcutaneous use

Understanding the Specific Implications of Amino Acids in the Antibody Development

As the demand for immunotherapy to treat and manage cancers, infectious diseases and other disorders grows, a comprehensive understanding of amino acids and their intricate role in antibody engineering has become a prime requirement. Naturally produced antibodies may not have the most suitable amino acids at the complementarity determining regions (CDR) and framework regions, for therapeutic purposes. Therefore, to enhance the binding affinity and therapeutic properties of an antibody, the specific impact of certain amino acids on the antibody's architecture must be thoroughly studied. In antibody engineering, it is crucial to identify the key amino acid residues that significantly contribute to improving antibody properties. Therapeutic antibodies with higher binding affinity and improved functionality can be achieved through modifications or substitutions with highly suitable amino acid residues. Here, we have indicated the frequency of amino acids and their association with the binding free energy in CDRs. The review also analyzes the experimental outcome of two studies that reveal the frequency of amino acids in CDRs and provides their significant correlation between the outcomes. Additionally, it discusses the various bond interactions within the antibody structure and antigen binding. A detailed understanding of these amino acid properties should assist in the analysis of antibody sequences and structures needed for designing and enhancing the overall performance of therapeutic antibodies.

Replacement and Immunomodulatory Activities of 20% Subcutaneous Immunoglobulin Treatment: A Single-Center Retrospective Study in Autoimmune Myositis and CVID Patients

Background

Immunoglobulin (Ig) replacement therapy represents a life-saving treatment in primary antibody deficiencies. The introduction of subcutaneous Ig (SCIg) administration brings a major improvement in quality of life for patients, compared to the traditional intravenous administration. In recent years, an additional role has been proposed for Ig therapy for various inflammatory and immune-mediated diseases. Consequently, the use of SCIg has expanded from immunodeficiencies to immune-mediated diseases, such as polymyositis (PM) and dermatomyositis (DM). Given the rarity of these conditions, it is still difficult to evaluate the real impact of SCIg treatment on PM and DM, and additional data are constantly required on this topic, particularly for long-term treatments in real-life settings.

Aim

This study aimed to increase the knowledge about the anti-inflammatory and immunomodulatory effects of SCIg treatment for myositis. To this aim, a long-term evaluation of the effectiveness of 20% human SCIg treatment (20% SCIg, Hizentra^®, CSL Behring) was carried out in patients with PM/DM in care at our Center. In addition, an evaluation of the 20% SCIg therapy in CVID patients was provided. This analysis, beside adding knowledge about the use of SCIg therapy in this real-life setting, was intended as a term of comparison, regarding the safety profile.

Results

Results support the beneficial effect and tolerability of long-term 20% SCIg therapy in PM/DM patients, reporting a significant improvement in creatine kinase levels, muscle strength, skin conditions, dysphagia, disease activity (MITAX score) and disability (HAQ-DI score). None of the patients reported systemic reactions. The duration of the reported local reactions was a few hours in 80% of the patients, and all resolved spontaneously. CVID patients reported an improvement in all the considered effectiveness parameters at the end of 20% SCIg therapy. The frequency of the adverse events reported by PM/DM patients was not different from what reported in CVID patients, where the use of SCIg therapy is more consolidated

Conclusions

This study suggests that 20% SCIg treatment represents a viable and safe treatment for PM/DM patients and a valid therapeutic alternative to IVIg, with important advantages for patients’ quality of life.

Association of blood IgG with tumor necrosis factor-alpha and clinical course of chronic lymphocytic leukemia

The intrinsic humoral immunodeficiency of chronic lymphocytic leukemia (CLL) is often managed with immunoglobulin replacement therapy (IgRT) to maintain IgG levels in the low-normal range (6–8 g/L) but optimal targets for IgG and timing to commence IgRT are unclear. IgG levels fell near 6 g/L at rates of −0.85±0.14 g/L/year in 51 patients who required treatment for CLL within 4.5±0.4 years from initial diagnosis and − 0.27±0.04 g/L/year in 40 patients with progressive disease who remained untreated after 8.5±0.5 years. In contrast, endogenous IgG levels remained above 8 g/L in patients with highly indolent disease (n = 25) and TNFα and beta-2-microglobulin (β2M) in blood decreased when IgRT was used to increase IgG levels over 9 g/L. At 15 g/L but not 5 g/L, the IgRT product Hizentra® inhibited B cell receptor (BCR)-activation, TNFα production, and survival in vitro, particularly of CLL cells that spontaneously made little TNFα. These findings suggest deterioration of the humoral immune system is associated with progressive CLL and altering the dosing of IgRT to achieve higher than conventional IgG target levels may have therapeutic activity.

•

Immunoglobulin levels decline at rates that reflect the clinical course of CLL.

•

IgG levels over 10 g/L achieved with replacement therapy are associated with evidence of disease control in vivo and inhibition of BCR-mediated activation of CLL cells in vitro.

•

Monitoring rates of decline of Ig levels in CLL patients gives biological information on disease severity.

•

Appropriate IgG target levels for immunoglobulin replacement therapy in CLL may be much higher than for patients with other immunodeficiencies.

IgPro20, the Polyneuropathy and Treatment with Hizentra® study (PATH), and the treatment of chronic inflammatory demyelinating polyradiculoneuropathy with subcutaneous IgG

Subcutaneous IgG (SCIG) administration may be preferred over the intravenous route (IVIG) in chronic inflammatory demyelinating polyneuropathy (CIDP) because it minimizes ‘end of cycle’ treatment-related fluctuations, reduces systemic adverse effects, improves convenience/quality of life and potentially lowers overall costs. Early reports of the use of highly concentrated SCIG preparations suggested they were effective and well-tolerated in chronic inflammatory demyelinating polyneuropathy. This was confirmed in the Polyneuropathy and Treatment with Hizentra® study of 172 subjects randomized to receive maintenance therapy with placebo or one of two doses of IgPro20 (20% IgG stabilized with L-Proline) for 6 months. Risk of relapse was reduced by SCIG in a dose-related manner as compared with placebo. A total of 88% of polyneuropathy and treatment with hizentra subjects felt the subcutaneous method was ‘easy to learn’. Local adverse events were mostly mild or moderate, and systemic adverse events were infrequent. Some patients may prefer maintenance therapy with SCIG over IVIG.

Reduction of Isoagglutinin in Intravenous Immunoglobulin (IVIG) Using Blood Group A- and B-Specific Immunoaffinity Chromatography: Industry-Scale Assessment

BACKGROUND

Hemolysis, a rare but potentially serious complication of intravenous immunoglobulin (IVIG) therapy, is associated with the presence of antibodies to blood groups A and B (isoagglutinins) in the IVIG product. An immunoaffinity chromatography (IAC) step in the production process could decrease isoagglutinin levels in IVIG.

OBJECTIVES

Our objectives were to compare isoagglutinin levels in a large number of IVIG (Privigen^®) batches produced with or without IAC and to assess the feasibility of the production process with an IAC step on an industrial scale.

METHODS

The IAC column comprised a blend of anti-A and anti-B resins formed by coupling synthetic blood group antigens (A/B-trisaccharides) to a base bead matrix, and was introduced towards the end of the industrial-scale IVIG manufacturing process. Isoagglutinin levels in IVIG were determined by anti-A and anti-B hemagglutinin direct and indirect methods according to the European Pharmacopoeia (Ph. Eur.) and an isoagglutinin flow cytometry assay. IVIG product quality was assessed with respect to the retention of immunoglobulin G (IgG) subclasses, specific antibodies, and removal of IgM using standardized procedures.

RESULTS

The IAC step reduced isoagglutinins in IVIG by two to three titer steps compared with lots produced without IAC. The median anti-A and anti-B titers with IAC were 1:8 and 1:4, respectively, when measured by the Ph. Eur. direct method, and 1:2 and <1, respectively, when measured by the Ph. Eur. indirect method. The isoagglutinin flow cytometry assay showed an 87-90 % reduction in isoagglutinins in post-IAC versus pre-IAC fractions. IAC alone reduced anti-A and anti-B of the IgMs isotype by 92.5-97.8 % and 95.4-99.2 %, respectively. Other product quality characteristics were similar with and without IAC.

CONCLUSIONS

IAC is an effective method for reducing isoagglutinin levels in IVIG, and it is feasible on an industrial scale.

Effect of IVIG Formulation on IgG Binding to Self- and Exo- Antigens In Vitro and In Vivo

In relation to the recent trials of Intravenous Immunoglobulin (IVIG) in Alzheimer’s Disease (AD) it was demonstrated that different IgG preparations contain varying amounts of natural anti-amyloid β (Aβ) antibodies as measured by ELISA. We therefore investigated the relevance of ELISA data for measuring low-affinity antibodies, such as anti-Aβ. We analysed the binding of different commercial Immunoglobulin G (IgG) preparations to Aβ, actin and tetanus toxoid in different binding assays to further investigate the possible cause for observed differences in binding to Aβ and actin between different IgG preparations. We show that the differences of commercial IgG preparations in binding to Aβ and actin in ELISA assays are artefactual and only evident in in vitro binding assays. In functional assays and in vivo animal studies the different IVIG preparations exhibited very similar potency. ELISA data alone are not appropriate to analyse and rank the binding capacity of low-affinity antibodies to Aβ or other endogenous self-antigens contained in IgG preparations. Additional analytical methods should be adopted to complement ELISA data.

Manufacture of immunoglobulin products for patients with primary antibody deficiencies - the effect of processing conditions on product safety and efficacy

Early preparations of immunoglobulin (Ig) manufactured from human plasma by ethanol (Cohn) fractionation were limited in their usefulness for substitution therapy in patients with primary antibody deficiencies (PAD), as Ig aggregates formed during manufacture resulted in severe systemic reactions in patients when given intravenously. Developments in manufacturing technology obviated this problem through the capacity to produce concentrated solutions of intact monomeric Ig, revolutionizing PAD treatment and improving patient life expectancy and quality of life. As the need for Ig has grown, manufacturers have refined further manufacturing technologies to improve yield from plasma and produce therapies, which are easier and less expensive to deliver. This has led to the substitution, partly or wholly, of ethanol precipitation by other techniques such as chromatography, and has also stimulated the production of highly concentrated solutions capable of rapid infusion. Ig products have been associated, since their inception, with certain adverse events, including infectious disease transmission, hemolysis, and thromboembolism. The introduction of standardized manufacturing processes and dedicated pathogen elimination steps has removed the risk of infectious disease, and the focus of attention has shifted to other problems, which appear to have increased over the past 5 years. These include hemolysis and thromboembolism, both the cause for substantial concern and the subject of recent regulatory scrutiny and actions. We review the development of manufacturing technology and the emerging evidence that changes for the optimization of yield and convenience has contributed to the recent incidents in certain adverse events. Industry measures under development will be discussed in terms of their potential to improve safety and optimize care for patients with PAD.

A 10% liquid immunoglobulin preparation for intravenous use (Privigen®) in paediatric patients with primary immunodeficiencies and hypersensitivity to IVIG

BACKGROUND

The objective of this study was to evaluate safety and efficacy of Privigen®, a 10% intravenous immunoglobulin (IVIG), in a particular group of paediatric patients (highly sensitive to previous IVIG infusion) affected with Primary Immunodeficiencies (PID).

MATERIAL AND METHODS

Patients (n=8) from 3 to 17 years old diagnosed of PID who often suffered from adverse events related to the infusion to previous IVIG were switched to Privigen® in an open protocol. Data were prospectively collected regarding Privigen® administration: infusion, safety and efficacy. In parallel, data on safety and tolerance were retrospectively collected from medical charts regarding the previous 10% IVIG product used.

RESULTS

50% of the patients required premedication with previous IVIG. At the end of the study none required premedication with Privigen®. The infusion rate was lower than that recommended by the manufacturer. All patients had suffered through adverse events during previous IVIG infusion being severe in three patients and recurrent in the rest. With Privigen® only three patients suffered from an adverse event (all cases were milder than previous related). Trough levels of IgG remained stable. None suffer from any episode of bacterial infection.

CONCLUSION

The present work shows that Privigen® was safe in a group of hypersensitive paediatric patients who did not tolerate the administration of a previous 10% liquid IVIG by using a particular infusion protocol slower than recommended. The number of adverse effects was smaller than published, and all cases were mild. No premedication was needed. Privigen® was also effective in this small group.

The expanding role of therapeutic antibodies

Therapeutic antibodies have been used since the end of nineteenth century, but their use is progressively increased and recently, with the availability of monoclonal antibodies, they are successfully employed in a large disease spectrum, which transversally covers different fields of medicine. Hyperimmune polyclonal immune globulin has been used against infectious diseases, in a period in which anti-microbial drugs were not yet available, and it still maintains a relevant place in prophylaxis/therapy. Although immune globulin should be considered life-saving as replacement therapy in humoral immunodeficiencies, its place in the immune-modulating treatment is not usually first-choice, but it should be considered as support to standard approved treatments. Despite therapeutic monoclonal antibodies have been lastly introduced in therapy, their extreme potentiality is reflected by the large number of approved molecules, addressed toward different immunological targets and able to heavily influence the prognosis and quality of life of a wide range of different diseases.

Management of a pregnant woman with common variable immunodeficiency and previous reactions to intravenous IgG administration

Common variable immunodeficiency is the most common symptomatic primary immunodeficiency in adulthood. Pregnant women with common variable immunodeficiency have different needs from other patients with the same disease. Because of immature state of the fetal and neonatal immune system, transplacental transfer of immunoglobulin G (IgG) has a relevant role in protecting the infant. We here report on a high-risk pregnant woman with common variable immunodeficiency with adverse reactions to intravenous immunoglobulin that was successfully rescued with a new Ig human intravenous, 10% liquid preparation. The treatment was tailored to the health status and characteristics of the patient. The new product was safe and well tolerated. The mother did not report any infections during pregnancy and the baby had a healthy course with 'protective' serum IgG levels. Our case is a further demonstration that intravenous immunoglobulin tolerability in patients with immunodeficiency could be linked to a product's characteristics.

Improved IgG3 levels and reduced infection rate in a woman with CVID switched from intravenous to subcutaneous immunoglobulin therapy

Aim: To report the interesting case of a patient with common variable immune deficiency disease who demonstrated varied responses to intravenous (IV) and subcutaneous (SC) immunoglobulin (Ig) therapy with regard to both infection frequencies and IgG3 subclass determinations. Patient & methods: As part of routine medical care, the author monitored total and IgG subclass levels, along with infection frequencies in a 35-year-old woman, with recurrent sinopulmonary infections diagnosed with common variable immune deficiency disease. Results: During treatment with IVIg, the patient’s annual rate of infections decreased, although she experienced severe headaches. After being switched to daily SCIg therapy, the headaches stopped, and her annual infection rate declined further. Her IgG3 levels, which were undetectable during IVIg therapy, increased substantially during SCIg treatment. Conclusion: The reason for the observed correlation between IgG3 level restoration and a decline in infection rate after being switched to SCIg therapy is not entirely clear. At the minimum, it may suggest that IgG3 levels may be a simple and useful surrogate marker to monitor Ig replacement sufficiency in certain patients.

Immune globulin subcutaneous (human) 20%: in primary immunodeficiency disorders

Immune globulin subcutaneous 20% is a new high-concentration (200 g/L) solution of highly purified human IgG (≥98%) indicated in the EU and the US for antibody replacement therapy in patients with primary immunodeficiency with antibody deficiency, and in the EU for replacement therapy in humoral immunodeficiency secondary to myeloma or chronic lymphocytic leukaemia.

Immune globulin subcutaneous 20% is formulated with L-proline, which imparts long-term stability at room temperature and a relatively low viscosity.

In two pivotal phase III trials in stably treated patients with primary immunodeficiency, immune globulin subcutaneous 20% at weekly subcutaneous dosages either equivalent to each patient’s previous intravenous or subcutaneous replacement therapy, or providing equivalent systemic exposure to previous intravenous therapy, produced mean serum IgG trough levels equal to or greater than pre-study levels. In each trial, there were no serious bacterial infections during treatment throughout the 28-week or 12-month efficacy periods. The rates of infectious episodes, days missed from work/school, days hospitalized or days with antibiotics were low.

Immune globulin subcutaneous 20% was generally well tolerated. A high proportion of patients experienced local infusion-site reactions, but infusion-related systemic adverse events were relatively infrequent. Most adverse events were of mild or moderate intensity and did not interfere with therapy.

Hemolysis upon intravenous immunoglobulin transfusion

Intravenous immunoglobulin (IVIG) is a mainstay of therapy in many disorders. An uncommon adverse side effect is IVIG-related hemolysis. Risk factors for IVIG-related hemolysis have been identified, including high dose IVIG given to non-O blood group recipients with an underlying inflammatory state. IVIG-related hemolysis has been linked to anti-A and anti-B hemagglutinins in the IVIG preparations and may involve both IgG and complement mediated hemolysis. A two-hit mechanism with threshold effect is proposed for IVIG-related hemolysis. Strategies exist to minimize or avoid IVIG-related hemolysis.