Recombinant human tumor necrosis factor receptor Fc fusion protein therapy in kidney transplant recipients undergoing OKT3 induction therapy.

BACKGROUND: Initial doses of OKT3 are associated with a cytokine-induced acute clinical syndrome (ACS). This study assessed the safety of a recombinant human tumor necrosis factor receptor fusion protein (TNFR:Fc) given to minimize OKT3-ACS symptoms in renal allograft recipients undergoing induction therapy. METHODS: Sixteen patients were randomized into treatment or control groups. Treated patients received TNFR:Fc 1 hr before OKT3 on days 0 and 3. Patients were monitored after transplant for OKT3-ACS symptoms. Levels of cytokines, serum creatinine, and C-reactive protein were followed. RESULTS: Patients receiving TNFR:Fc had lower OKT3-ACS symptoms as measured by a scoring system. There was a higher incidence of infection in treated patients (10/12) compared to controls (1/4) in the 3 months after transplant, but the etiology of this difference was unclear. There were no significant differences in cytokine profiles. CONCLUSIONS: TNFR:Fc is well tolerated by renal transplant patients receiving OKT3 induction therapy and modestly decreases the symptoms associated with OKT3-ACS.

The CD11b promoter directs high-level expression of reporter genes in macrophages in transgenic mice.

CD11b is the alpha chain of the Mac-1 integrin and is preferentially expressed in myeloid cells (neutrophils, monocytes, and macrophages). We have previously shown that the CD11b promoter directs cell-type-specific expression in myeloid lines using transient transfection assays. To confirm that these promoter sequences contain the proper regulatory elements for correct myeloid expression of CD11b in vivo, we have used the -1.7-kb human CD11b promoter to direct reporter gene expression in transgenic mice. Stable founder lines were generated with two different reporter genes, a Thy 1.1 surface marker and the Escherichia coli lacZ (beta-galactosidase) gene. Analysis of founders generated with each reporter demonstrated that the CD11b promoter was capable of driving high levels of transgene expression in murine macrophages for the lifetime of the animals. Similar to the endogenous gene, transgene expression was preferentially found in mature monocytes, macrophages, and neutrophils and not in myeloid precursors. These experiments indicate that the -1.7 CD11b promoter contains the regulatory elements sufficient for high-level macrophage expression. This promoter should be useful for targeting heterologous gene expression to mature myeloid cells.

Treatment of rheumatoid arthritis with a recombinant human tumor necrosis factor receptor (p75)-Fc fusion protein.

BACKGROUND: Tumor necrosis factor (TNF) is a proinflammatory cytokine involved in the pathogenesis of rheumatoid arthritis, and antagonism of TNF may reduce the activity of the disease. This study evaluated the safety and efficacy of a novel TNF antagonist - a recombinant fusion protein that consists of the soluble TNF receptor (p75) linked to the Fc portion of human IgG1 (TNFR:Fc). METHODS: In this multicenter, double-blind trial, we randomly assigned 180 patients with refractory rheumatoid arthritis to receive subcutaneous injections of placebo or one of three doses of TNFR:Fc (0.25, 2, or 16 mg per square meter of body-surface area) twice weekly for three months. The clinical response was measured by changes in composite symptoms of arthritis defined according to American College of Rheumatology criteria. RESULTS: Treatment with TNFR:Fc led to significant reductions in disease activity, and the therapeutic effects of TNFR:Fc were dose-related. At three months, 75 percent of the patients in the group assigned to 16 mg of TNFR:Fc per square meter had improvement of 20 percent or more in symptoms, as compared with 14 percent in the placebo group (P<0.001). In the group assigned to 16 mg per square meter, the mean percent reduction in the number of tender or swollen joints at three months was 61 percent, as compared with 25 percent in the placebo group (P<0.001). The most common adverse events were mild injection-site reactions and mild upper respiratory tract symptoms. There were no dose-limiting toxic effects, and no antibodies to TNFR:Fc were detected in serum samples. CONCLUSIONS: In this three-month trial TNFR:Fc was safe, well tolerated, and associated with improvement in the inflammatory symptoms of rheumatoid arthritis.

Etanercept therapy in rheumatoid arthritis. A randomized, controlled trial.

BACKGROUND: In a phase II study, etanercept (recombinant human tumor necrosis factor receptor [p75]:Fc fusion protein) safely produced rapid, dose-dependent improvement in rheumatoid arthritis over 3 months. OBJECTIVE: To confirm the benefit of etanercept therapy of longer duration and simplified dosing in patients with rheumatoid arthritis. DESIGN: Randomized, double-blind, placebo-controlled trial with blinded joint assessors. SETTING: 13 North American centers. PATIENTS: 234 patients with active rheumatoid arthritis who had an inadequate response to disease-modifying antirheumatic drugs. INTERVENTION: Twice-weekly subcutaneous injections of etanercept, 10 or 25 mg, or placebo for 6 months. MEASUREMENTS: The primary end points were 20% and 50% improvement in disease activity according to American College of Rheumatology (ACR) responses at 3 and 6 months. Other end points were 70% ACR responses at 3 and 6 months and other measures of disease activity at 3 and 6 months. RESULTS: Etanercept significantly reduced disease activity in a dose-related fashion. At 3 months, 62% of the patients receiving 25 mg of etanercept and 23% of the placebo recipients achieved 20% ACR response (P < 0.001). At 6 months, 59% of the 25-mg group and 11% of the placebo group achieved a 20% ACR response (P < 0.001); 40% and 5%, respectively, achieved a 50% ACR response (P < 0.01). The respective mean percentage reduction in the number of tender and swollen joints at 6 months was 56% and 47% in the 25-mg group and 6% and -7% in the placebo group (P < 0.05). Significantly more etanercept recipients achieved a 70% ACR response, minimal disease status (0 to 5 affected joints), and improved quality of life. Etanercept was well tolerated, with no dose-limiting toxic effects. CONCLUSIONS: Etanercept can safely provide rapid, significant, and sustained benefit in patients with active rheumatoid arthritis.