PRTX-100 and methotrexate in patients with active rheumatoid arthritis: A Phase Ib randomized, double-blind, placebo-controlled, dose-escalation study.

PRTX-100 is a highly-purified preparation of staphylococcal protein A (SpA), with immunologic activity in vitro and in animal models of immune-mediated inflammation. Following single-dose healthy volunteer studies of safety and pharmacokinetics (PK), a multicenter, double-blind, placebo-controlled, sequential dose-escalation, repeated-dose phase I trial was conducted in patients with active rheumatoid arthritis (RA) on methotrexate therapy. Patients were randomized to receive either weekly intravenous PRTX-100 (0.15, 0.45, 0.90, or 1.50 µg/kg) or placebo for 4 weeks. Safety and disease activity were assessed over 16 weeks. Pharmacokinetic profiles were obtained after the first and fourth doses. The most common treatment-related adverse events were nausea, muscle spasms, dizziness, flushing, fatigue, RA flare, and headache. No serious adverse events were considered related to PRTX-100, and none occurred in the highest dose group. Geometric mean values for plasma Cmax (ng/mL) were 4.1, 15.7, 26.5, and 51.2 for doses of 0.15, 0.45, 0.90, and 1.5 µg/kg, respectively. Anti-drug antibodies (ADAs) developed in most PRTX-100 patients, but incidence and titer were not dose-dependent. At the two highest doses, data suggest PRTX-100 may have an effect on RA disease activity, even in patients with ADAs.

Acute glomerulonephritis occurring during immunoadsorption with staphylococcal protein A column (Prosorba).

BACKGROUND: Apheresis of patient plasma by immunoadsorption with a staphylococcal protein A (SPA) column is used in a variety of autoimmune disorders. Leukocytoclastic vasculitis is an uncommon severe complication that can occur during immunoadsorption with SPA (Prosorba. METHODS: We report a case of immune complex glomerulonephritis occurring during Prosorba immunoabsorption in a patient with rheumatoid arthritis (RA). Using a Medline literature search and information provided by Cypress Bioscience/Fresenius Hemocare, we review renal complications associated with Prosorba immunoadsorption. RESULTS: We identified seven additional potential cases of glomerulonephritis (GN) in association with Prosorba immunoadsorption. Five of these patients were being treated for RA, and two for idiopathic thrombocytopenia purpura (ITP). Renal biopsies were performed on four patients, all of whom had evidence of immune complex GN. Among RA patients treated with Prosorba, the incidence of GN closely paralleled that of leukocytoclastic vasculitis at 1.75%. The presence of leukocytoclastic vasculitis was a significant risk factor for the development of GN (relative risk = 75.95, CI 7-1869, P = 0.00021). In contrast, among more than 10 000 ITP patients treated with Prosorba, there were only two potential cases of GN. The risk of developing GN in association with Prosorba immunoadsorption was significantly greater for patients with RA than for those with ITP (relative risk = 62.95, CI 10-453, P = 0.00002). CONCLUSION: This case series highlights the risk of GN among patients undergoing SPA immunoadsorption. The development of GN is associated with the presence of leukocytoclastic vasculitis. Patients with RA seem to be at particular risk.

Vasculitis secondary to staphylococcal Protein A immunoadsorption (Prosorba column) treatment in rheumatoid arthritis.

OBJECTIVE: Vasculitis is a rare complication of immunoadsorption treatment with staphylococcal Protein A (Prosorba column). The prevalence, clinical characteristics, pathophysiology, treatment, and outcome of vasculitis secondary to immunoadsorption treatment is not known. METHODS: The authors describe a 57-year-old woman with rheumatoid arthritis (RA) resistant to methotrexate and etanercept, who developed severe leukocytoclastic vasculitis after the 9th weekly treatment with Prosorba column. She developed rapidly progressive crescentic glomerulonephritis and required treatment with cyclophosphamide and high-dose prednisone. Subsequently, renal function stabilized and RA remitted. Through the literature search and by reviewing information submitted to Cypress Biosciences Inc (manufacturer of Prosorba columns), available world literature on vasculitis secondary to Prosorba column treatment was compiled. RESULTS: Immune complex deposition of staphylococcal Protein A (SPA)/SPA antibodies in the glomeruli precipitated the renal disease in our patient. Twenty cases of vasculitis (calculated prevalence, 1 per 400), 5 with internal organ involvement, have been reported in patients treated with Prosorba column for thrombocytopenic purpura. Seven RA patients treated with Prosorba column developed vasculitis (prevalence, 7 per 400), 3 with internal organ involvement. CONCLUSIONS: Vasculitis secondary to staphylococcal Protein A immunoadsorption therapy occurs rarely and appears to be related to development of SPA/SPA antibody immune complexes. Rheumatologists should be aware of this potentially serious complication of the Prosorba column treatment for RA.

Leukocytoclastic vasculitis following staphylococcal protein A column immunoadsorption therapy for idiopathic thrombocytopenic purpura.

A patient with refractory idiopathic thrombocytopenic purpura developed widespread palpable purpura, fever, diarrhea, and arthralgias forty-eight hours following a third protein A immunoadsorption treatment. A skin biopsy revealed leukocytoclastic vasculitis. His skin lesions and constitutional symptoms resolved with administration of antibiotics and bed rest.

A pilot study using a staph protein A column (Prosorba) to treat refractory rheumatoid arthritis.

OBJECTIVE: To assess the safety and effectiveness of extracorporeal treatments with protein A (Prosorba) columns in the treatment of patients with severe refractory rheumatoid arthritis (RA) in an open label pilot study. METHODS: Fifteen patients with RA who had failed to respond to 2 or more disease modifying antirheumatic drugs were "washed out" for 1-3 months before enrollment into this 6 month pilot study. The treatment schedule called for patients to receive apheresis treatments across staphylococcal protein A columns once a week for 12 weeks. Clinical evaluations of RA activity, defined by Paulus criteria, were conducted at study enrollment (baseline) and monthly throughout the treatment phase. In addition, examinations were conducted at 2, 4, 8, and 12 weeks after the last treatment. Fourteen patients received all 12 scheduled treatments, while one patient received only 10 treatments due to complications secondary to pneumonia. RESULTS: Using Paulus 50% criteria, 9 of 15 (60%) patients were improved at the 4th month, and one more fulfilled >20% Paulus criteria (7%) in the 5th month after starting therapy. The study group reported an average of 2.47 adverse effects per treatment, of which the most common were joint pain and swelling and fatigue of short duration (arthritic flare). CONCLUSION: The adverse effects associated with this apheresis based treatment proved to be manageable and of short duration and resolved without sequelae. The results suggest that extracorporeal protein A therapy may have a role in the management of refractory RA, and encouraged the initiation of a larger, blinded, controlled clinical trial.

Leukocytoclastic vasculitis following staphylococcal protein A column immunoadsorption therapy. Two cases and a review of the literature.

BACKGROUND: Protein A immunoadsorption is a novel therapy for the treatment of diseases mediated by pathogenic autoantibodies. This procedure consists of circulating patients' plasma through a column containing staphylococcal protein A, which binds to the Fc portion of IgG, enabling removal of IgG. Presently, protein A immunoadsorption is used in the treatment of idiopathic thrombocytopenic purpura, but may be more widely used as an immunomodulator in human immunodeficiency virus infection and metastatic carcinoma. OBSERVATIONS: We present two histologically documented cases of leukocytoclastic vasculitis in the setting of protein A immunoadsorption. This potentially severe adverse effect is probably more common than the literature reflects and should be recognized by physicians who are treating patients with protein A column pheresis. CONCLUSIONS: The pathogenesis of protein A therapy-associated leukocytoclastic vasculitis remains unclear. Further study of vasculitis in the setting of protein A column pheresis may lead to modifications of this therapy, resulting in fewer adverse effects. Protein A-associated leukocytoclastic vasculitis may serve as a useful model of the relation of immune complexes and vasculitis.

Treatment of refractoriness to platelet transfusion by protein A column therapy.

Ten thrombocytopenic patients (platelets < 10-24 x 10(9)/L) who were refractory to platelet transfusion were investigated for their responsiveness to staphylococcal protein A column therapy. Nine patients had previously been treated with steroids, intravenous immune globulin, and/or other forms of immunosuppressive therapy without improvement in their transfusion response. All patients were receiving multiple platelet transfusions without achieving 1-hour corrected count increments (CCIs) > or = 7500. Eight patients had antibodies that reacted with platelets and were directed against HLA class I antigens, ABO antigens, and/or platelet-specific alloantigens. Plasma (500-2000 mL) from each patient was passed over a protein A silica gel column and then returned to the patient. Patients received from 1 to 14 treatments. A positive response to protein A therapy was defined as at least a doubling of the pretreatment platelet count and/or two successive 10- to 120-minute posttransfusion CCIs > or = 7500. Following plasma treatments, 6 of 10 patients responded with daily platelet counts that averaged 48 +/- 11 x 10(9) per L as compared with counts of 16 +/- 7 x 10(9) per L (p < 0.0005) before treatment. Posttransfusion CCI values determined in four of these patients averaged 2480 +/- 810 and 10,010 +/- 3540 (p < 0.005) before and after treatment, respectively. In contrast, among the four unresponsive patients, platelet counts averaged 10 +/- 9 and 13 +/- 10 x 10(9) per L (p = NS), respectively, while posttransfusion CCIs were 700 +/- 1410 and 1520 +/- 2460 (p = NS), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of congenital and acquired hemophilia patients by extracorporeal removal of antibodies to coagulation factors: a review of US clinical studies 1987-1990. Hemophilia Study Group.

This paper reviews the use of extracorporeal immunoadsorption with immobilized Staphylococcal Protein A in attempts to lower the inhibitor titer in 22 patients with either congenital hemophilia or with acquired inhibitors. Eighty-five immunoadsorption procedures were performed at 13 locations in the United States between June, 1987 and February, 1990. In general, immunoadsorption was shown to efficiently remove IgG and, in eight congenital hemophilia patients, it also produced a clinically significant lowering of inhibitors allowing effective conventional factor replacement therapy. Three of thirteen congenital hemophilia patients treated received factor concentrate prior to immunoadsorption and were anamnestic at the time of treatment. Although they experienced substantial lowering of their inhibitor titers, it was not sufficient to allow effective factor replacement. The effectiveness of immunoadsorption therapy in the 9 patients with acquired inhibitors was more difficult to evaluate due to the wide variety of concomitant medications which were employed, although in several patients serious bleeding episodes were substantially improved (or halted) following immunoadsorption. Side effects associated with immunoadsorption were slight. These findings suggest that immunoadsorption can be a significant benefit to patients with inhibitors, particularly if it is instituted prior to factor administration.

The use of protein A columns in the treatment of cancer and allied diseases.

The staphylococcal cell-wall protein known as protein A has been explored as a therapeutic modality in the treatment of cancer and allied diseases. Protein A binds the Fc fragment of IgG 1, 2 and 4, and preferentially binds to IgG incorporated into immune complexes. Early investigators focused on the immune-suppressive effects of immune complexes in cancer and, based on in vitro experiments, postulated that clearance of immune complexes in vivo would permit effective immune clearance of cancer cells. A large clinical trial of the perfusion of cancer patient plasma over protein A was subsequently undertaken. Results were generally disappointing, with no complete remissions and overall response rates of 22%. Response rates for Kaposi's sarcoma (39%) and breast adenocarcinoma (26%) were somewhat encouraging, and further clinical trials in these disorders are ongoing. More impressive have been the responses to protein A perfusion in immune thrombocytopenia and hemolytic-uremic syndrome. Using a protein A-silica device, Snyder et al. reported responses in 42% of immune thrombocytopenia patients, with mean increases in platelet count from 27 x 10(9)/l to 120 x 10(9)/l. On the basis of these results, the protein A-silica column was approved by the United States Food and Drug Administration for treatment of immune thrombocytopenia. Equally encouraging are reports of an overall 59% response rate in cancer chemotherapy-related hemolytic-uremic syndrome. Reported toxicities include fever, chills, hypotension, dyspnea and musculoskeletal pain. With rare exceptions, these reactions are easily treated and do not result in cessation of therapy. Unfortunately, the mechanism of action of plasma perfusion over protein A is very unclear.(ABSTRACT TRUNCATED AT 250 WORDS)

Delayed treatment with a t-PA analogue and streptokinase in a rabbit embolic stroke model.

Fibrinolytic therapy may be effective in the treatment of ischemic stroke, and clinical trials are under way. We evaluated two fibrinolytic agents, an analogue of tissue plasminogen activator (Fb-Fb-CF, the catalytic fragment of the tissue plasminogen activator molecule with a prolonged serum half-life, n = 10) and streptokinase (n = 7), in a rabbit model of embolic stroke. Both agents were given 3 hours after stroke onset, a time relevant to the clinical setting. Fb-Fb-CF was significantly better (p less than 0.04) than saline (n = 7) in restoring blood flow to previously occluded intracranial arteries, but streptokinase was ineffective. Neither fibrinolytic agent was associated with a substantial risk for intracerebral hemorrhagic side effects. Our study demonstrates that Fb-Fb-CF can safely and effectively reperfuse rabbit intracranial arteries 3 hours after occlusion, while streptokinase does not.

Immune thrombocytopenia purpura: a pilot study of staphylococcal protein A immunomodulation in refractory patients.

Idiopathic thrombocytopenia purpura (ITP) is a primary immune thrombocytopenia that is typically manifested in adults by acute bleeding, severe thrombocytopenia, and normal to increased megakaryocytes in the bone marrow. Labeling studies suggest that most patients with ITP have an IgG antibody directed against the platelet membrane resulting in sequestration in the spleen. Splenectomy and/or corticosteroids remain the mainstay of therapy, with permanent remissions induced in 75% of patients. Despite the use of cyclophosphamide, azathioprine, vincristine, high-dose gamma globulin, and other forms of therapy, less than 50% of refractory patients achieve long-term satisfactory platelet counts. In view of these facts, ten consecutive patients with immune thrombocytopenia, unrelated to human immunodeficiency virus (HIV), received plasma perfusion over a staphylococcal protein A column (PROSORBA column) to evaluate efficacy and toxicity. All patients had an initial platelet count less than 50,000 and had failed corticosteroids. Five patients had also failed splenectomy. Two patients were not splenectomized due to pediatric age, two due to severe coexisting medical conditions, and one due to refusal of operation. Multiple other forms of therapy had also failed in this cohort of patients. Patients received two to ten treatments with the protein A column. All patients are evaluable for response and toxicities. Of the ten patients, results were as follows: complete response in one (platelet count greater than 150,000); partial response in four (platelet count greater than 50,000 and less than 150,000); and no response in five. Duration of responses ranged from 1 to 6 or more months.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of immunoadsorption therapy by a protein A column on patients with thrombocytopenia.

Immunoadsorption therapy employing protein A columns (PROSORBA columns) was used for the treatment of patients with naturally occurring or transfusion-induced immune thrombocytopenia purpura (ITP). Plasma from one unit of blood was perfused through the columns and returned to each patient. This procedure was performed once or twice weekly. In two cases of acute ITP, platelets markedly increased, and platelet-associated IgG (Pa-IgG) and circulating immune complexes (CIC) were decreased following the treatments. A transient increase in platelets was achieved in one patient with chronic ITP. Some improved response to platelet transfusions was noticed in one patient with aplastic anemia and platelet alloimmunization. Two mechanisms are suggested for the effect of protein A column therapy: one is the stimulation of the production of anti-idiotype antibody that neutralizes platelet auto-antibody and the other is activation of complement that induces solubilization and removal of CIC containing platelet autoantibodies. Immunoadsorption by protein A column is a useful therapy for some ITP cases, especially those that are acute.

Treatment of patients with HIV thrombocytopenia and hemolytic uremic syndrome with protein A (Prosorba column) immunoadsorption.

Both antibodies and circulating immune complexes (CIC), which bind to platelets and induce the destruction and clearance of platelets by the reticuloendothelial system, are found in patients with human immunodeficiency virus (HIV) and immune thrombocytopenic purpura (ITP). IgG and CIC were removed from patients' plasma by extracorporeal immunoadsorption using protein A-silica columns (PROSORBA columns). Of the 36 HIV-positive ITP patients treated, 29 received more than one treatment and were evaluated for response. Sixteen patients showed more than a 50% increase in their platelet counts. Platelet-associated IgG (PAIgG) and/or platelet-directed IgG and CIC were elevated in all patients. After four to eight treatments, 16 of 29 patients showed a 170% to 430% increase in platelet counts. A decrease in CIC and PAIgG was noted in responding patients. The median duration of response to date was 8 to 12 months. This treatment was associated with immune modulation and the development of an anti-F (ab')2 antibody response. The antibody functions by complexing with both platelet-binding IgG and CIC, neutralizing their binding capacity for platelets and enhancing their clearance from the circulation. Nine patients with mitomycin-C-induced hemolytic uremic syndrome (HUS) were also treated with PROSORBA columns. Pretreatment platelet counts were markedly reduced while a definite increase in platelet counts was observed upon completion of therapy. There was a decrease of hemolysis and stabilization of renal function in three patients. PROSORBA column treatment has demonstrated marked activity against both HIV-ITP and HUS, and has successfully freed patients from the bleeding diathesis associated with these syndromes.

Protein A immunotherapy in the treatment of cancer: an update.

Protein A, a naturally occurring Staphylococcus aureus cell surface protein, has the unusual property of binding circulating immune complexes and immunoglobulin G with high avidity. CIC have played a major role in cancer-associated immunosuppression. Thus, removal of the immunosuppressive agents, ie, the CIC, may lead to a modulation of the immunosuppression and a liberation of the immune system to perform an antitumor effect. In animal studies, protein A has been used in extracorporeal immunoadsorption columns and treatments have resulted in tumor shrinkage and antiviral responses. Our group developed a multicenter clinical trial to assess toxicity and antitumor responses with this biologic response modifier alone. This is an update of our original trial. We have now treated 142 patients for a total of 1,306 treatments. The patients consisted of 74 males and 68 females. Their age ranged from 7 to 83 years, with a mean of 50 years. The Karnofsky performance index values ranged from 40 to 95, with a mean of 80. Patients who received seven or more treatments were considered eligible for tumor response assessment, and all patients with one or more treatments were eligible for toxicity assessment. Thus, there were 101 patients eligible for tumor response and 142 eligible for toxicity response. The total response rate was 22 patients or 21.8% (partial remission [PR], 12 patients, 12%; less than PR, 10 patients, 10%). Response rates were similar in the 13 treatment centers. Toxicity was assessed in 142 patients. One thousand three hundred six treatments were assessed for treatment toxicity.(ABSTRACT TRUNCATED AT 250 WORDS)