Complex formation between methionine and a heme peptide from cytochrome c.
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Animals↗
Biomedical subjects
M W Fanger
Publications and source records attributed to M W Fanger.
Fc gamma RI blockade and modulation for immunotherapy.
Splenectomy and corticosteroids are the treatment of choice for patients with immune thrombocytopenic purpura (ITP). However, for the 10%-15% of patients who do not respond to conventional therapy, high-dose i.v. IgG can induce life-saving transient responses. The benefits of i.v. IgG have been attributed to Fc receptor blockade; however, the involvement of the individual Fc receptors for IgG (Fc gamma R) in ITP remain to be more completely defined. Recently a mAb, designated mAb H22, which recognizes an epitope on Fc gamma RI (CD64) outside the ligand-binding domain, was humanized. Because mAb H22 is a human IgG1 and Fc gamma RI has a high affinity for human IgG1 antibodies, we predicted that mAb H22 would bind to the Fc gamma RI ligand-binding site through its Fc domain and to its external Fc gamma RI epitope through both Fab domains. These studies demonstrate that mAb H22 blocked Fc gamma RI-mediated phagocytosis of opsonized red blood cells more effectively than an irrelevant IgG. Moreover, cross-linking Fc gamma RI with mAb H22 down-modulated Fc gamma RI expression on monocytes, an effect seen within 2 h.
Antibodies, Monoclonal↗
Macrophage-targeted killing and vaccines.
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Antibodies, Bispecific↗
Phase I pilot trial of the bispecific antibody MDXH210 (anti-Fc gamma RI X anti-HER-2/neu) in patients whose prostate cancer overexpresses HER-2/neu.
The goal of this study was to evaluate, in patients with prostate cancer, the toxicity profile and biologic activity of the bispecific antibody MDXH210, which has specificity for the non-ligand-binding site of the high-affinity immunoglobulin G receptor (Fc gamma RI) and the extracellular domain of the HER-2/neu proto-oncogene product. Patients with prostate cancer that expressed HER-2/neu were entered into a phase I dose-escalation trial of MDXH210. Patients received an intravenous infusion MDXH210 during a period of 2 h three times per week for 2 weeks and were monitored for toxicity. Pharmacokinetic and pharmacodynamic parameters were measured and included the biologic end points of monocyte-bound MDXH210, cytokine production, and clinical response. Seven patients were treated with MDXH210 doses ranging from 1 to 8 mg/m2. In general, MDXH210 was well tolerated, with only mild infusion-related malaise, fever, chills, and myalgias. No dose-limiting toxic effects were observed. Biologic effects included induction of low plasma concentrations of tumor necrosis factor-alpha and interleukin-6 observed immediately after MDXH210 infusion and 70% saturation of circulating monocyte-associated Fc gamma RI with MDXH210 at a dose level of 4 to 8 mg/m2. Five of six patients had stable prostate-specific antigen levels during the course of 40 days or more. Circulating plasma HER-2/neu levels decreased by 80% at days 12 and 29 (p = 0.03 and 0.06, respectively, by the Wilcoxon signed rank test). MDXH210 can be given safely to patients with HER-2/neu-positive prostate cancer in doses of at least 8 mg/m2. At the doses studied, biologic activity was demonstrated and characterized by binding of MDXH210 to circulating monocytes, release of monocyte-derived cytokines, a decrease in circulating HER-2/neu, and short-term stabilization of prostate-specific antigen levels.
Aged↗