Clinical evaluation of a staphylococcal protein A immunoadsorption system in the treatment of myasthenia gravis patients

Profile of the single-use, multiple-pass protein A adsorber column in immunoadsorption

BACKGROUND AND OBJECTIVES

Immunoadsorptions (IA) are used to remove autoantibodies from the plasma in autoimmune disorders. In this study, we evaluated the effects of a single-use, recombinant staphylococcal protein A-based immunoadsorber on blood composition of the patient.

MATERIALS AND METHODS

In a cohort of patients with myasthenia gravis or stiff-person syndrome, essential parameters of blood cell count, coagulation, clinical chemistry or plasma proteins and immunoglobulins (Ig) were measured before and after IA (n = 11).

RESULTS

In average, IA reduced the levels of total IgG, IgG1, IgG2 and IgG4 by approximately 60%, the acetylcholine receptor autoantibody levels by more than 70%. IgG3, IgA or IgM were diminished to a lower extent. In contrast to fibrinogen or other coagulation factors, the column markedly removed vitamin K-dependent coagulation factors II, VII, IX and X by approximately 40%-70%. Accordingly, international normalized ratio and activated partial thromboplastin time were increased after IA by 59.1% and 32.7%, respectively. Coagulation tests almost returned to baseline values within 24 h. Blood cell count, electrolytes, total protein or albumin were not essentially affected. No clinical events occurred.

CONCLUSION

The single-use, multiple-pass protein A adsorber column is highly efficient to remove IgG1, IgG2 and IgG4 or specific acetylcholine receptor autoantibodies from the plasma. Coagulation parameters should be monitored, since the column has the capacity to largely reduce vitamin K-dependent factors.

Neuromuscular junction disorders

Diseases of the neuromuscular junction comprise a wide range of disorders. Antibodies, genetic mutations, specific drugs or toxins interfere with the number or function of one of the essential proteins that control signaling between the presynaptic nerve ending and the postsynaptic muscle membrane. Acquired autoimmune disorders of the neuromuscular junction are the most common and are described here. In myasthenia gravis, antibodies to acetylcholine receptors or to proteins involved in receptor clustering, particularly muscle-specific kinase, cause direct loss of acetylcholine receptors or interfere with the agrin-induced acetylcholine receptor clustering necessary for efficient neurotransmission. In the Lambert-Eaton myasthenic syndrome (LEMS), loss of the presynaptic voltage-gated calcium channels results in reduced release of the acetylcholine transmitter. The conditions are generally recognizable clinically and the diagnosis confirmed by serologic testing and electromyography. Screening for thymomas in myasthenia or small cell cancer in LEMS is important. Fortunately, a wide range of symptomatic treatments, immunosuppressive drugs, or other immunomodulating therapies is available. Future research is directed to understanding the pathogenesis, discovering new antigens, and trying to develop disease-specific treatments.

Immunoadsorption in patients with autoimmune ion channel disorders of the peripheral nervous system

Autoimmune ion channel disorders of the peripheral nervous system include myasthenia gravis, the Lambert-Eaton myasthenic syndrome, acquired neuromyotonia and autoimmune autonomic ganglionopathies. These disorders are characterized by the common feature of being mediated by IgG autoantibodies against identified target antigens, i.e. the acetylcholine receptor, the voltage-gated calcium and potassium channels, and the neuronal acetylcholine receptor. Moreover, experimental animal models have been identified for these diseases that respond to immunotherapy and are improved by plasmapheresis. On this basis, autoimmune ion channel disorders represent the ideal candidate for therapeutic apheresis. Immunoadsorption can be the treatment of choice when intensive apheretic protocols or long-term treatments must be performed, in patients needing frequent apheresis to keep a stable clinical condition, in case of unresponsiveness to corticosteroids and immunosuppressive treatments, or failure with TPE or intravenous immunoglobulins, and in patients with severe contraindications to long-term corticosteroids.

Current and future immunotherapy in myasthenia gravis

Current therapy for myasthenia gravis is directed towards generalized modulation and suppression of the immune system. These approaches have been extensively studied and are effective in many patients with myasthenia, but at the cost of significant adverse effects due to the global effects on the immune system. Future directions in therapy are geared towards focused immunotherapies that aim to improve outcomes while lessening the burden of side effects. This paper reviews both the current accepted treatments for myasthenia gravis as well as promising targeted therapies in development.

Plasma exchange for rheumatoid arthritis

Rheumatoid arthritis (RA) is the most common inflammatory joint disease. Even though, physiopathology of rheumatoid arthritis remains unclear, the presence of circulating immune complexes and rheumatoid factors had led to the use of plasma exchange (PE). Even though PE procedures have evolved over the last decades, their indications and use in RA must be replaced in the context of the evolution of disease-modifying anti-rheumatic drugs. Results of PE and leukapheresis were disappointing in patients with severe and resistant RA. Conversely, immunoadsorption, and particularly over a Staphylococcus aureus protein A column, has resulted in some good responses in refractory RA patients. But, the emergence of effective biologics has clearly restrained their use and limited their indications to some rare patients with refractory and severe RA.

Long-term Effects of a Multimodal Approach Including Immunoadsorption for the Treatment of Myasthenic Crisis

A multimodal treatment protocol with immunoadsorption (IA) as the central element was used in the treatment of myasthenic crisis (MC). Fifteen patients with MC were treated in repeated, uninterrupted 7-day cycles until mobilization with: (i) large-volume IA using an antihuman-IgG adsorber, days 1-5; (ii) intravenous immunoglobulin substitution (0.3-0.5 g/kg body weight [BW]/day), days 5-7; and (iii) immunosuppression with cyclophosphamide (1-2 mg/kg BW/day) and prednisolone (0.5-1 mg/kg BW/day), until remission. Patients required a median of 8 days of mechanical ventilation, 12 days in the intensive care unit, and 35 days of hospitalization. Functional improvement compared to their precrisis condition was attained by 14 of 15 patients. MG severity score improved by a mean of 10 points, quality of life score by 9.8 points, and Karnofsky index by 29 points in 14 of 15 patients. Improvements remained stable and no further crises occurred during long-term follow-up, which averaged 4.4 years. No fatalities due to MC occurred. The results demonstrate that our protocol is a potent therapeutic approach in the treatment of MC.

A pilot study to compare the use of the Excorim staphylococcal protein immunoadsorption system and IVIG in chronic inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an immune mediated neuropathy responding to immunomodulation with IVIG or plasma exchange (PE). We tested the efficacy and safety of selective immunoglobulin removal by Excorim immunoadsorption (IA) in a pilot trial in CIDP patients randomized to monthly IA or IVIG treatments for 6 months. Response rates at 2 and 6 months were greater with IA due to longer disease duration and greater disability at baseline in the patients receiving IVIG. IA appears to be a safe and efficacious therapy for patients with CIDP, but an appropriately powered clinical trial with stratification for disease duration is required.

Removal of Pathogenic Autoantibodies by Immunoadsorption

Autoimmune diseases result from disrupted tolerance to self-antigens and subsequent damage to tissues and organs. In several diseases, specific autoantibodies have been either proved or suspected to play a role in this process. Consequently, several strategies have been devised in an attempt to discard the destructive immunoglobulins. Currently, both nonselective and epitope-specific methods are applied in several diseases. In this review, we provide a summary of the available data on elimination of pathogenic autoantibodies and discuss the advantages and pitfalls of the different approaches.

Protein L-agarose for Adsorption of Autoantibodies: A Potential Tool for Extracorporeal Treatment

This work investigated the adsorption of autoantibodies such as anti-SS-A/Ro, anti-SS-B/La, anti-Sm, and anti-dsDNA on protein L-agarose gel. In order to determine better conditions for IgG adsorption on this matrix, some buffer systems were tested. Adsorption data were analyzed using the Langmuir and Langmuir-Freundlich isotherm models. The experimental isotherms were best described by the Langmuir-Freundlich model, which indicated negative and positive cooperativities for binding in the presence of PBS and HEPES buffers, respectively. The K(d) values for phosphate buffered saline solution (PBS) and hydroxyethylpiperazine ethanesulfonic acid (HEPES) were 2.8 x 10(-7) M and 3.2 x 10(-7) M, respectively, which indicate a high affinity between IgG and the immobilized protein L. The amount of protein adsorbed per amount of protein loaded was high for anti-Sm (44%) and anti-dsDNA (46%), but low for anti-SS-B/La (9%). The amount of albumin adsorbed was lower than 0.06 mg/mL, which may remove the need for a plasma replacement solution in clinical apheresis.

Immunoadsorption may provide a cost-effective approach to management of patients with inhibitors to FVIII

BACKGROUND

Immunoadsorption of plasma with Staphylococcal protein A removes immunoglobulins and immune complexes; hence, it should effectively remove inhibitors to FVIII in acquired or congenital hemophilia. The procedure may be cost effective, given the expense of therapies used to treat patients with inhibitors, particularly in an acute setting.

STUDY DESIGN AND METHODS

Three patients with inhibitors to FVIII were treated with the Excorim Immunosorba system (two columns used in tandem). Costs for immunoadsorption and for other therapeutic products administered to the patients were calculated.

RESULTS

Two patients had acquired hemophilia and severe bleeding associated with low levels of circulating FVIII and high levels of inhibitors to FVIII. They failed to achieve a satisfactory response to management with immunosuppression, pFVIII, recombinant FVIIa or IVIG but responded rapidly, with long-term benefit, to immunoadsorption therapy. The third patient had congenital hemophilia and immunoadsorption was effective in reducing his inhibitor level, allowing him to undergo immune tolerance therapy. Costs of treatment before immunoadsorption were markedly higher than those associated with the immunoadsorption procedures (i.e., >Can 350,000 dollars and >Can 1,000,000 dollars vs. < 20,000 dollars).

CONCLUSION

Immunoadsorption appears to be an effective and cost-effective alternative in the management of patients with inhibitors to FVIII.

Long-term treatment of myasthenia gravis with immunoadsorption

Acute treatment of myasthenic crisis with immunoadsorption (IA) or plasma exchange is well established. The efficiency of chronic apheresis therapy in myasthenia gravis (MG), however, and its efficacy in reducing concomitant potentially harmful immunosuppressive therapy, is unknown. We treated 13 patients with therapy-resistant MG or severe steroid or azathioprine therapy-related side effects, or both, with long-term IA [median, 38 (range: 16-59) months]. IA was performed every second day until partial remission was achieved (modified Osserman score <2). Subsequently, oral immunosuppressive therapy was reduced and the frequency of IA adapted to the clinical symptoms. After initiation of IA the mean (SEM) Osserman score decreased from 3.23 +/- 0.12 to 1.23 +/- 0.08 within 1 month (P < 0.01). Mean azathioprine dose was reduced concomitantly from 89 +/- 9.4 mg/day to 56 +/- 11 mg/day (P < 0.05), and mean prednisolone dose from 41 +/- 7.6 mg/day to 22 +/- 8.5 mg/day (P < 0.05). After 36 months the number of IA-sessions/month had been reduced from 4.81 +/- 0.24 to 2.64 +/- 0.4 (P < 0.05), the mean azathioprine dose to 25 +/- 17 mg/day and the mean prednisolone dose to 9 +/- 3.6 mg/day. Six out of thirteen patients were weaned from IA after a median of 33 (range, 16-50) months and a decrease of the Osserman score to 0.33 +/- 0.33. In these patients MG remained stable during a follow-up period of 28 (range, 16-38) months. We conclude that long-term IA enables the reduction of oral immunosuppressants in patients with contraindications or resistance to steroid and azathioprine therapy. Furthermore, almost 50% of the patients can be weaned from IA with then substantial lower need of further immunosuppressive therapy.

Protein A Sepharose immunoadsorption can restore the efficacy of platelet concentrates in patients with Glanzmann's thrombasthenia and anti-glycoprotein IIb-IIIa antibodies

Type I Glanzmann's thrombasthenia is a rare congenital platelet function disorder, characterized by undetectable platelet membrane glycoprotein IIb-IIIa (GPIIb-IIIa). Severe bleeding is controlled by transfusion of normal platelets, leading in some cases to the occurrence of anti-GPIIb-IIIa isoantibodies, which induces a loss of transfused platelet efficacy. We used immunoadsorption on protein A Sepharose (IA-PA), which has been shown to be efficient in decreasing the titre of antibodies in several immune diseases, in three patients with Glanzmann's thrombasthenia and anti-GPIIb-IIIa isoantibodies on five different occasions. IA-PA was well tolerated with no deleterious side-effects reported. It induced a dramatic decrease of total immunoglobulin (Ig)G, including anti-GPIIb-IIIa isoantibody levels, as assessed by the monoclonal antibody-specific immobilization of platelet antigens test and the ex vivo inhibition of normal platelet aggregation induced by the patient's platelet-rich or platelet-poor plasma. Elimination of the antibody was associated with a correction of the bleeding time following platelet transfusion. IA-PA combined with platelet transfusion made it possible to control two life-threatening haemorrhages, and allowed two surgical procedures and one bone marrow transplantation to be performed safely. Our experience suggests that IA-PA, which restores the haemostatic efficacy of platelet transfusion, is a valuable therapeutic strategy in patients with Glanzmann's thrombasthenia and anti-GPIIb-IIIa isoantibodies.

In myasthenia gravis, clinical and immunological improvement post-thymectomy segregate with results of in vitro antibody secretion by immunocytes

In myasthenia gravis (MG), presence of pathogenic acetylcholine receptor antibodies (AchRAb) and thymic pathology are related. Our study assesses the long-term clinical outcome of thymectomy as a function of thymic pathologies, AchRAb levels in blood and the ability of immunocytes to secrete AchRAb ex vivo. We found that those patients who have thymocytes that secrete AchRAb in vitro have a greater decrease in their need for Mestinon over the 60 months of follow-up than the non-secretors (p = 0.04). Those patients whose cultured peripheral blood mononuclear cells (PBMC) secreted AchRAb also had a greater decrease in Mestinon requirements over the 60 months of follow-up than the non-secretors (p = 0.05), however, differences between the two groups at each individual assessment were not statistically significant. Serial post-op AchRAb measurements in sera of thymocyte and PBMC non-secretors showed no change from pre-op levels (< 10 nmol/l), while secretors had a reduction of more than 80% from pre-op levels, starting 6 months post-op. We also found that results of PBMC culture at time of thymectomy is a better predictor of response to thymectomy than serum AchRAb levels but inferior to results of thymocytes cultures. Patients with thymoma had the highest proportion of individuals secreting AchRAb from thymocytes in culture (78%), the shortest duration of disease (9 months) and showed the greatest trend toward improvement in clinical signs and symptoms post-op. We have thus demonstrated the long held suspicion that removal of actively secreting cells from the thymus at an early time in the disease confers the greatest benefit.

Background and indications for protein A-based extracorporeal immunoadsorption

Protein A (SPA), a major cell wall component of Staphylococcus aureus, has occupied numerous investigators from its discovery in the late fifties. Its availability and avid binding to human immunoglobulins have led to extensive usage for diagnostic and research purposes. Today, SPA-based extracorporeal immunoadsorption relies on two rather different systems, namely, SPA-silica (Prosorba), and SPA-Sepharose (Immunosorba). Both systems are approved by the Food and Drug Administration for the core indications of rheumatoid arthritis and idiopathic thrombocytopenic purpura (SPA-silica) or hemophilia with inhibitors (SPA-Sepharose). Off label indications include immune disorders with a conceivable connection between autoantibody titers and disease activity, like forms of glomerulonephritis, systemic lupus erythematodes, myasthenia, and the Guillain-Barré syndrome as well as alloantibody formation in the context of e.g., transplantation. This review summarizes historical developments and important properties of SPA. Indications for extracorporeal therapy are discussed on the basis of available information and personal experience.

Local anticoagulation of the extracorporeal circuit with heparin and subsequent neutralization with protamine during immunoadsorption

A regimen of local anticoagulation of an immunoadsorption device was studied. The extracorporeal circuit was anticoagulated with citrate (5.5%) and a continuous infusion of heparin (2,000 U/h or 1,500 U/h), which was neutralized by a continuous infusion of protamine chloride (75% of the heparin dose) before reinfusion in 23 patients treated with low-density lipoprotein or immunoglobulin apheresis. Sufficient anticoagulation of the extracorporeal circuit was obtained (activated partial thromboplastin time [APTT] > 180 seconds; thrombin time [TT] > 120 seconds; anti-Xa activity, 1.05 +/- 0.21 U/mL) during the entire treatment of 190 minutes, whereas coagulation parameters in the patients' blood stayed within the normal range. In a control group without heparin neutralization, full systemic anticoagulation of the patients occurred (APTT, 157.8 +/- 30.6 seconds; TT, 119.8 +/- 0.4 seconds; anti-Xa activity, 0.88 +/- 0.21 U/mL). No side effects or clotting of the system were observed. Our data show that this regimen of local anticoagulation is a safe protocol for extracorporeal circulation without exposing the patients to anticoagulants.

Therapeutic apheresis in myasthenia gravis

Plasma exchange (PE) is an easily applicable technique for rapid and massive removal of antibodies, and its beneficial role is well established in the management of myasthenia gravis (MG), an antibody-mediated disorder of the neuromuscular junction. PE is useful in myasthenic crisis, in most severe forms of MG before thymectomy, in the early postoperative period, and in cases of symptom worsening during tapering or initiation of immunosuppressive therapy. Clinical efficacy varies from 55% to 100%, and improvement rarely persists for more than 4-10 weeks; thus immunosuppressive therapy has to be associated. New apheretic techniques (double filtration plasmapheresis, immunoadsorption systems with staphylococcal protein A columns or thryptophan-polyvinyl alcohol gel columns) that allow the selective removal of IgG and anti-AChR antibody were recently used in the management of MG with positive effects. Whether their therapeutic effect and cost effect prove more favorable than those obtained by PE still must be demonstrated.

Removal of xenoreactive antibodies by protein-A immunoadsorption: experience in 22 patients

The presence of naturally occurring anti-Galalpha1-3Gal (antialphaGal) Ab in human serum is believed to be a major factor in the pathogenesis of hyperacute rejection of discordant organ xenografts such as the pig-to-human combination. Galalpha1-3Gal epitopes are expressed on pig tissues and the binding of anti-Galalpha1-3Gal leads to endothelial cell activation and complement-mediated hyperacute graft rejection. Several strategies have been suggested in donor animals or in the xenograft recipient to overcome the anti-alphaGal barrier. Protein-A immunoadsorption (PAIA) was developed for the in vivo removal of circulating Ab and it has been shown to be effective in cases where pathogenic auto or alloAb are present. The aim of our study was to analyze the effect of PAIA on total and xenoreactive serum anti-alphaGal immunoglobulin levels in a group of patients treated with this technique for different diseases. After three consecutive sessions of PAIA, total and xenoreactive IgG and IgM immunoglobulin levels were decreased by more than 50% of pre-treatment levels. So we conclude that PAIA is an effective method to significantly reduce circulating Ab, including xenogeneic IgM and IgG Ab. This mode of therapy might be considered as a tool to overcome hyperacute xenograft rejection. PAIA combined with other therapeutic approaches may well protect the xenograft.