Antibodies to vaccine antigens in pooled polyclonal human IgG products.

Immune-deficient patients depend on the antibodies in pooled human immunoglobulin G (IgG) preparations to remain free from serious infections. The potency of IgG preparations is therefore an ongoing concern. The use of pooled IgG to prevent infection is based on the concept that healthy adults have recovered from infections earlier in life and maintain relatively high antibody titers. In general, vaccine-induced immunity is less robust or long-lasting than immunity after natural infection, and many infectious diseases which were formerly widely prevalent have become much less common due to improved hygiene and vaccines. This raises questions as to the adequacy of protective antibodies in current IgG preparations. This paper reviews available data on antibodies against selected bacterial and virus vaccine antigens in current IgG products. Most products contain sufficient antibody to yield levels above minimal protective concentrations to a broad range of pathogens and toxins. Illustrative examples of effects of vaccines on antibody content of IgG products are also discussed: antibody titers to hepatitis A virus in donor plasma pools in both the US and EU are dropping due to decreased natural infection, but they are still sufficient to provide robust protection. Increasing seroprevalence of hepatitis B virus as a result of immunization suggests that antibody titers against this virus may actually be increasing. Finally, serial studies suggest that pooled IgG provides protection against seasonal influenza viruses despite year-to-year antigenic drift, and is also likely to provide at least some protective antibody against potentially pandemic strains.

Individualized immunoglobulin therapy in chronic immune-mediated peripheral neuropathies.

Despite the well-recognized importance of immunoglobulin therapy individualization during the treatment of chronic inflammatory demyelinating polyneuropathy (CIDP), the pathway to best achieve optimization is unknown. There are many pharmacokinetic and immunobiologic variables that can potentially influence the appropriateness of any individual therapy. Although identification of specific autoantibodies and their targets has only been accomplished in a minority of patients with CIDP, already the diagnostic and treatment implications of specific autoantibody detection are being realized. Individual variability in IgG pharmacokinetic properties including IgG catabolic rates and distribution, as well as the IgG level necessary for disease control also require consideration during the optimization process. For optimization to be successful there must be a measure of treatment response that has a clinically meaningful interpretation. There are currently available well-defined and validated clinical assessment tools and outcome measures that are well suited for this purpose. While there remains much to learn on how best to manipulate immunopathology and immunoglobulin pharmacokinetics in the most favorable way, there currently exists an understanding of these principles to a degree sufficient to begin to develop rational and evidence-based treatment optimization strategies.

Optimizing IgG therapy in chronic autoimmune neuropathies: a hypothesis driven approach.

Prolonged intravenous immunoglobulin (IVIG) therapy is used for the chronic autoimmune neuropathies chronic idiopathic demyelinating polyneuropathy and multifocal motor neuropathy, but the doses and treatment intervals are usually chosen empirically due to a paucity of data from dose-response studies. Recent studies of the electrophysiology and immunology of these diseases suggest that antibody-induced reversible dysfunction of nodes of Ranvier may play a role in conduction block and disability which responds to immunotherapy more rapidly than would be expected for demyelination or axonal damage per se. Clinical reports suggest that in some cases, the effects of each dose of IVIG may be transient, wearing-off before the next dose is due. These observations lead us to hypothesize that that therapeutic IgG acts by competing with pathologic autoantibodies and that individual patients may require different IgG levels for optimal therapeutic effects. Frequent IVIG dosing and weekly subcutaneous IgG have been tried as ways of continuously maintaining high serum IgG levels, resulting in stabilization of neuromuscular function in small case series. Frequent grip strength and disability measurements, performed by the patient at home and reported electronically, can be used to assess the extent and duration of responses to IgG doses. Individualization of IgG treatment regimens may optimize efficacy, minimize disability, and identify nonresponders.

Clinical experience with an L-proline­stabilized 10 %intravenous immunoglobulin (Privigen®): real-life effectiveness and tolerability.

PURPOSE: This retrospective study evaluated the effectiveness and tolerability in clinical practice of an L-proline-stabilized 10 % intravenous immunoglobulin (IVIG; Privigen®) in patients with primary (PID) or secondary immunodeficiency (SID). METHODS: Patients from 6 centers in Europe and the US were treated with individually determined regimens of Privigen® for ≥3 months. Serum immunoglobulin G (IgG) trough levels, annualized rates of infection, hospitalization and antibiotics use, and the incidence of adverse events (AEs) were analyzed. RESULTS: Of 72 patients, three infants with severe combined immunodeficiency (SCID) were analyzed separately. The remaining 69 patients (52.2 % male; median age 38 years [range: 0.1-90.0]) with PID (82.6 %) or SID (17.4 %) received a mean (±standard deviation) Privigen® dose of 532 ± 250 mg/kg/month resulting in trough serum IgG levels of 407-1,581 mg/dL (median: 954 mg/dL). Ten patients (14.5 %) experienced 11 serious bacterial infections over 22.0 ± 15.0 months of treatment (0.087 events/patient/year, upper one-sided 99 % confidence interval: 0.170), the most common being pneumonia (11.6 %). The rates for any infection and hospitalization were 1.082 events/patient/year and 3.63 days/patient/year, respectively. Two patients with severe disease accounted for 303 of 460 hospital days. Across all 72 patients, 13 (18.1 %) patients experienced AEs, including 10 (13.9 %) patients with AEs at least possibly related to Privigen®, including headache (8.3 %), fever, and chills (2.8 % each). No related serious AEs were reported. One infant with SCID died due to severe viral infection. CONCLUSIONS: Despite the heterogeneous population, effectiveness and tolerability of Privigen® in clinical practice closely matched those reported in clinical studies.

Bioavailability of IgG administered by the subcutaneous route.

PURPOSE: US licensing studies of subcutaneous IgG (SCIG) calculate dose adjustments necessary to achieve area under the curve (AUC) of serum IgG vs. time on SCIG that is non-inferior to that on intravenous IgG (IVIG), within the FDA-set limit of ±20%. The results are interpreted as showing that different SCIGs differ in bioavailability. We used three approaches to determine if the bioavailabilities were actually different. METHODS: Dose adjustments and AUCs from published licensing studies were used to calculate bioavailabilities using the formula: Bioavailability (% of IVIG) = AUC(SCIG) ÷ AUC(IVIG) x 1/Dose Adjustment. We also compared the increment in serum IgG concentration achieved with varying doses of SCIG in recent meta-analyses with the increment with different doses of IVIG, and determined the serum IgG concentrations when patients switched SCIG products at the same dose. RESULTS: The actual bioavailabilities were: Gamunex® 65.0%, Hizentra® 65.5%, Gammagard® 67.2%, Vivaglobin® 69.0%. Regression analyses of serum IgG vs. dose showed that the mean increase in serum IgG resulting from a 100 mg/kg/month increment in SCIG dosing was 69.4% of the increase with the same increment in IVIG dosing (84 mg/dL vs. 121 mg/dL). Patients switching SCIG preparations at the same dose had no change in serum IgG levels, confirming that bioavailabilities of the SCIG preparations did not differ. CONCLUSIONS: Decreased bioavailability appears to be a basic property of SCIG and not a result of any manufacturing process or concentration. Because serum IgG levels do not vary with different SCIG products at the same dose, adjustments are not necessary when switching products.

Rapid and reversible responses to IVIG in autoimmune neuromuscular diseases suggest mechanisms of action involving competition with functionally important autoantibodies.

Intravenous immunoglobulin (IVIG) is widely used in autoimmune neuromuscular diseases whose pathogenesis is undefined. Many different effects of IVIG have been demonstrated in vitro, but few studies actually identify the mechanism(s) most important in vivo. Doses and treatment intervals are generally chosen empirically. Recent studies in Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy show that some effects of IVIG are readily reversible and highly dependent on the serum IgG level. This suggests that in some autoantibody-mediated neuromuscular diseases, IVIG directly competes with autoantibodies that reversibly interfere with nerve conduction. Mechanisms of action of IVIG which most likely involve direct competition with autoantibodies include: neutralization of autoantibodies by anti-idiotypes, inhibition of complement deposition, and increasing catabolism of pathologic antibodies by saturating FcRn. Indirect immunomodulatory effects are not as likely to involve competition and may not have the same reversibility and dose-dependency. Pharmacodynamic analyses should be informative regarding most relevant mechanism(s) of action of IVIG as well as the role of autoantibodies in the immunopathogenesis of each disease. Better understanding of the role of autoantibodies and of the target(s) of IVIG could lead to more efficient use of this therapy and better patient outcomes.

Higher doses of subcutaneous IgG reduce resource utilization in patients with primary immunodeficiency.

The recommended dose of IgG in primary immunodeficiency (PID) has been increasing since its first use. This study aimed to determine if higher subcutaneous IgG doses resulted in improved patient outcomes by comparing results from two parallel clinical studies with similar design. One patient cohort received subcutaneous IgG doses that were 1.5 times higher than their previous intravenous doses (mean 213 mg/kg/week), whereas the other cohort received doses identical to previous subcutaneous or intravenous doses (mean 120 mg/kg/week). While neither cohort had any serious infections, the cohort maintained on higher mean IgG dose had significantly lower rates of non-serious infections (2.76 vs. 5.18 episodes/year, P < 0.0001), hospitalization (0.20 vs. 3.48 days/year, P < 0.0001), antibiotic use (48.50 vs. 72.75 days/year, P < 0.001), and missed work/school activity (2.10 vs. 8.00 days/year, P < 0.001). The higher-dose cohort had lower health care utilization and improved indices of well being compared to the cohort treated with traditional IgG doses.

Pharmacokinetics of subcutaneous immunoglobulin and their use in dosing of replacement therapy in patients with primary immunodeficiencies.

Bioavailability and pharmacokinetics of subcutaneous IgG (SCIG) and intravenous IgG (IVIG) differ. It is not clear if and/or how the dose should be adjusted when switching from IVIG to SCIG. Area under the curve (AUC) of serum IgG versus time and trough level ratios (TLRs) on SCIG/IVIG were evaluated as guides for adjusting the dose. The mean dose adjustments required for non-inferior AUCs with 2 different SCIG preparations were 137% (± 12%) and 153% (± 16%). However, there were wide variations between adjustments required by different subjects, and in the resulting TLRs. In contrast, combined data from multiple studies allow estimation of the ratio of IgG levels with different dose adjustments, and of the steady state serum levels with different SCIG doses. When switching a patient from IVIG to SCIG, individualizing the dosage based on measured serum IgG levels and the clinical response is preferable to using mean pharmacokinetic parameters.

Incidence of infection is inversely related to steady-state (trough) serum IgG level in studies of subcutaneous IgG in PIDD.

Results from seven studies of four subcutaneous IgG preparations in patients with primary immune deficiencies show that the incidence of infection is inversely related to the steady-state IgG level. Maintaining higher IgG levels may be beneficial, and no given level is necessarily adequate for all patients.

Use of intravenous immunoglobulin and adjunctive therapies in the treatment of primary immunodeficiencies: A working group report of and study by the Primary Immunodeficiency Committee of the American Academy of Allergy Asthma and Immunology.

There are an expanding number of primary immunodeficiency diseases (PIDDs), each associated with unique diagnostic and therapeutic complexities. Limited data, however, exist supporting specific therapeutic interventions. Thus, a survey of PIDD management was administered to allergists/immunologists in the United States to identify current perspectives and practices. Among 405 respondents, the majority of key management practices identified were consistent with existing data and guidelines, including the provision of immunoglobulin therapy, immunoglobulin dosing and selective avoidance of live viral vaccines. Practices for which there are little specific data or evidence-based guidance were also examined, including evaluation of IgG trough levels for patients receiving immunoglobulin, use of prophylactic antibiotics and recommendations for complementary/alternative medicine. Here, variability applied to PIDD patients was identified. Differences between practitioners clinically focused upon PIDD and general allergists/immunologists were also identified. Thus, a need for expanded clinical research in PIDD to optimize management and potentially improve outcomes was defined.

Efficacy, pharmacokinetics, safety, and tolerability of Flebogamma 10% DIF, a high-purity human intravenous immunoglobulin, in primary immunodeficiency.

BACKGROUND: Flebogamma 10% DIF represents an evolution of intravenous immune globulin from the previous 5% product to be administered at higher rates and with smaller infusion volumes. Pathogen safety is enhanced by the combination of multiple methods with different mechanisms of action. OBJECTIVE: The objective of this study as to evaluate the efficacy, pharmacokinetics, and safety of Flebogamma 10% DIF for immunoglobulin replacement therapy in primary immunodeficiency diseases (PIDD). METHODS: Flebogamma 10% DIF was administered to 46 subjects with well-defined PIDD at a dose of 300-600 mg/kg every 21-28 days for 12 months. RESULTS: Serious bacterial infection rate was 0.025/subject/year. Half-life in serum of the administered IgG was approximately 35 days. No serious treatment-related adverse event (AE) occurred in any patient. Most of the potentially treatment-related AEs occurred during the infusion, accounting for 20% of the 601 infusions administered. CONCLUSIONS: Flebogamma 10% DIF is efficacious and safe, has adequate pharmacokinetic properties, and is well-tolerated for the treatment of PIDD.

Improved quality of life, immunoglobulin G levels, and infection rates in patients with primary immunodeficiency diseases during self-treatment with subcutaneous immunoglobulin G.

OBJECTIVES: Primary immunodeficiency diseases (PIDDs) include a large class of genetically heterogeneous disorders which predispose patients to significant risk of serious and chronic/recurrent infections, as well as reduced quality of life (QoL). Intravenous immunoglobulin (IVIG) therapy improves the well being of PIDD patients; however, the need for venous access and potentially severe side effects frequently require administration in medical facilities. We evaluated the long-term (12-month) experience with home-based self infusions of subcutaneous immune globulin (SCIG) in patients with PIDD on health-related QoL, rates of serious bacterial infections, and all other infections. METHODS: Adults (n = 42) and children (n = 9) with PIDD, previously treated with clinic-based IVIG, were trained to self administer SCIG at home. QoL (SF-36(R) and CHQ-PF50 questionnaires), serious bacterial infections, serum immunoglobulin G (IgG) levels, overall infections, and incidence of adverse events were recorded at predetermined intervals. RESULTS: All patients had improved perceptions of general health (adults P = 0.047, children P = 0.037). Adults also had marked improvement in the bodily pain and vitality assessments, and parents had improved perceptions of personal and family activities. Serum IgG levels were maintained at mean levels 25% higher than previous troughs on IVIG. There were 162 infections overall for an annual rate of 3.42/patient, but only 1 serious bacterial infection was observed (0.03/patient/yr). An average of 4.5 days/yr was missed from work or school per patient. CONCLUSIONS: Home SCIG therapy was safe and led to improved perceptions of general health, higher serum IgG levels, and very low rates of infections and days missed from work/school.

Hereditary angioedema C1-esterase inhibitor replacement therapy and coexisting autoimmune disorders: findings from a claims database.

In this letter to the editor, we present results of claims data analysis. This claims data analysis supports a hypothesis that in patients with hereditary angioedema due to C1-esterase inhibitor (C1-INH) deficiency, the occurrence and/or symptomatology of coexisting autoimmune disease may be positively influenced by a replacement therapy with plasma derived C1-INH.

Subcutaneous administration of IgG.

The availability of IgG preparations that could be administered safely by the intravenous route was finally achieved in the early to mid-1980s. Intravenous immunoglobulin (IVIG) revolutionized the treatment of primary immune deficiency diseases (PIDD) and led to the discovery of the therapeutic value of high-dose IgG in autoimmune and inflammatory diseases not associated with PIDD. Improved therapy has improved outcomes and expectations, and most PIDD patients can lead fully active and productive lives. Administration of IgG by the subcutaneous route is effective and safe and overcomes obstacles to the use of IVIG in some patients. Many patients find administration of subcutaneous IgG at home more convenient than receiving IVIG at the Doctor's office or hospital. The coming years will see increased use of subcutaneous immunoglobulin in PIDD, which will be facilitated by advances leading to higher-concentration IgG products and easier delivery.

Principles of and advances in immunoglobulin replacement therapy for primary immunodeficiency.

During the last 2 decades, the continued development and the large-scale production of polyclonal immune serum globulin (ISG) preparations with improved safety and tolerability profiles have allowed treatment to focus on quality of life and long-term freedom from the complications of primary immune deficiency disease, rather than just on freedom from severe acute infections and survival. Available ISG preparations allow routine therapy by a variety of routes and regimens that can be tailored to suit individual patients. Continued vigilance is required, however, because problems with emerging diseases, and the costs and availability of ISG are likely to present continuing challenges.

Management of primary antibody deficiency with replacement therapy: summary of guidelines.

This article summarizes the guidelines for using replacement therapy in the management of patients who have primary antibody deficiency.

Chronic inflammation in the cystic fibrosis lung: alterations in inter- and intracellular signaling.

A vicious cycle of airway obstruction, infection, and inflammation continues to cause most of the morbidity and mortality in cystic fibrosis (CF). Mutations that result in decreased expression or function of the membrane Cl(-) channel, cystic fibrosis transmembrane regulator (CFTR), result in a decrease in the volume (and hence the depth) of liquid on the airway surface, impaired ciliary function, and dehydrated glandular secretions. In turn, these abnormalities contribute to a milieu, which promotes chronic infection with a limited but unique spectrum of microorganisms. Defects in CFTR also perturb regulation of several intracellular signaling pathways including signal transducers and activator of transcription, I-kappaB and nuclear factor-kappa B, and low molecular weight GTPases. Together, these abnormalities result in excessive production of NF-kappaB dependent cytokines such as interleukin (IL)-1, tumor necrosis factor (TNF), IL-6, and IL-8. There are decreased responses to interferon gamma and transforming growth factor beta leading to decreased production of iNOS and NO. Abnormalities of lipid mediators and decreased secretion of counter/regulatory cytokines have also been reported. Together, these effects combine to create a chronic inflammatory process, which damages and obstructs the airways, and eventually claims the life of the patient.

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.

Immunoglobulin therapy in hematologic neoplasms and after hematopoietic cell transplantation.

Immunoglobulins are used to prevent or reduce infection risk in primary immune deficiencies and in settings which exploit its anti-inflammatory and immune-modulatory effects. Rigorous proof of immunoglobulin efficacy in persons with lympho-proliferative neoplasms, plasma cell myeloma, and persons receiving hematopoietic cell transplants is lacking despite many clinical trials. Further, there are few consensus guidelines or algorithms for use in these conditions. Rapid development of new therapies targeting B-cell signaling and survival pathways and increased use of chimeric antigen receptor T-cell (CAR-T) therapy will likely result in more acquired deficiencies of humoral immunity and infections in persons with cancer. We review immunoglobulin formulations and discuss efficacy and potential adverse effects in the context of preventing infections and in graft-versus-host disease. We suggest an algorithm for evaluating acquired deficiencies of humoral immunity in persons with hematologic neoplasms and recommend appropriate use of immunoglobulin therapy.