Safety, immunogenicity, pharmacokinetics, and efficacy of the IgG‐degrading enzyme of Streptococcus pyogenes (IdeS imlifidase) were assessed in a single‐center, open‐label ascending‐dose study in ...highly sensitized patients with chronic kidney disease. Eight patients with cytotoxic PRAs (median cytotoxic PRAs of 64%) at enrollment received 1 or 2 intravenous infusions of IdeS on consecutive days (0.12 mg/kg body weight ×2 n = 3; 0.25 mg/kg ×1 n = 3, or 0.25 mg/kg ×2 n = 2). IgG degradation was observed in all subjects after IdeS treatment, with <1% plasma IgG remaining within 48 hours and remaining low up to 7 days. Mean fluorescence intensity values of HLA class I and II reactivity were substantially reduced in all patients, and C1q binding to anti‐HLA was abolished. IdeS also cleaved the IgG‐type B cell receptor on CD19+ memory B cells. Anti‐IdeS antibodies developed 1 week after treatment, peaking at 2 weeks. A few hours after the second IdeS infusion, 1 patient received a deceased donor kidney offer. At enrollment, the patient had a positive serum crossmatch (HLA‐B7), detected by complement‐dependent cytotoxicity, flow cytometry, and multiplex bead assays. After IdeS infusion (0.12 mg/kg ×2) and when the HLA‐incompatible donor (HLA‐B7+) kidney was offered, the HLA antibody profile was negative. The kidney was transplanted successfully.
In highly sensitized patients with chronic kidney disease, the immunoglobulin G–degrading enzyme of Streptococcus pyogenes (imlifidase) degrades plasma IgG efficiently, reduces HLA antibodies substantially, and abolishes C1q binding to anti‐HLA, thus enabling HLA‐incompatible kidney transplantation.
This multicenter, first-in-human study evaluated safety, tolerability, pharmacokinetics, and pharmacodynamics of BI-505, a human anti-ICAM-1 monoclonal antibody, in advanced relapsed/refractory ...multiple myeloma patients.
BI-505 was given intravenously, every 2 weeks, at escalating doses from 0.0004 to 20 mg/kg, with extension of therapy until disease progression for responding or stable patients receiving 0.09 mg/kg or higher doses.
A total of 35 patients were enrolled. The most common adverse events were fatigue, pyrexia, headache, and nausea. Adverse events were generally mild to moderate, and those attributed to study medication were mostly limited to the first dose and manageable with premedication and slower infusion. No maximum tolerated dose was identified. BI-505's half-life increased with dose while clearance decreased, suggesting target-mediated clearance. The ICAM-1 epitopes on patient bone marrow myeloma were completely saturated at 10 mg/kg doses. Using the International Myeloma Working Group criteria, 7 patients on extended therapy had stable disease for more than 2 months.
BI-505 can be safely administered at doses that saturate myeloma cell ICAM-1 receptors in patients. This study was registered at www.clinicaltrials.gov (NCT01025206).
Abstract Background TB-403 (RO5323441) is a humanized monoclonal antibody directed against placental growth factor (PlGF). Preclinical studies have demonstrated that targeting PlGF can result in ...significant inhibition of tumor growth and metastasis. Objectives The purpose of this study was to assess the safety profile, tolerability, and pharmacokinetics of TB-403, developed for the treatment of solid tumors. Methods Healthy male subjects were exposed to a single intravenous infusion of TB-403 or placebo. Blood samples for hematology, clinical chemistry, coagulation factors, and urinalysis were collected; vital signs and ECGs were recorded; and serial blood samples were drawn for pharmacokinetic and immunogenicity measurements and circulating levels of pharmacodynamics markers PlGF and (VEGF) vascular endothelial growth factor. Sixteen subjects received either placebo or TB-403 at doses ranging from 0.3 to 5.0 mg/kg. Results Mild (grade 1 or 2) nasopharyngitis, headache, neck pain, and joint pain were the most frequently reported adverse events (AEs). There were no serious AEs in the study, and none of the AEs led to withdrawal. None of the safety laboratory assessments was considered clinically significant, and none was reported as an AE. There were no apparent differences in terms of safety profiles among the 3 dose levels of active treatment compared with placebo. Clearance, volume of distribution, and terminal t½ (mean values) for TB-403 in all 3 cohorts were in the range of 4.2 to 4.9 (mL/d/kg), 56 to 79 (mL/kg), and 8 to 13 (days), respectively. Conclusion The highest dose of TB-403 (5.0 mg/kg) was well tolerated in this study of a single intravenous infusion to healthy males. This result allowed a higher starting dose level in a subsequent Phase I study in cancer patients, the patient population for which this antibody is developed.
Oxidized low-density lipoprotein (LDL) plays an essential role in the pathogenesis of atherosclerosis. The purpose of this study was to characterize the pharmacokinetics (PK) of a human recombinant ...IgG1 antibody to oxidized LDL (anti-oxLDL) in cynomolgus monkey. The tissue biodistribution of anti-oxLDL was also investigated using positron emission tomography (PET) imaging.
Anti-oxLDL was conjugated with the N-hydroxysuccinimide ester of DOTA (1,4,7,10-tetraazacyclododecane 1,4,7,10-tetraacetic acid) and radiolabeled by chelation of radioactive copper-64 ((64)Cu) for detection by PET. Anti-oxLDL was administered as a single intravenous (IV) dose of 10 mg/kg (as a mixture of radiolabeled and non-labeled material) to two male and two female cynomolgus monkeys. Serum samples were collected over 29 days. Two ELISA methods were used to measure serum concentrations of anti-oxLDL; Assay A was a ligand binding assay that measured free anti-oxLDL (unbound and partially bound forms) and Assay B measured total anti-oxLDL. The biodistribution was observed over a 48-hour period following dose administration using PET imaging.
Anti-oxLDL serum concentration-time profiles showed a biphasic elimination pattern that could be best described by a two-compartment elimination model. The serum concentrations obtained using the two ELISA methods were comparable. Clearance values ranged from 8 to 17 ml/day/kg, while beta half-life ranged from 8 to 12 days. The initial volume of distribution and volume of distribution at steady state were approximately 55 mL/kg and 150 mL/kg, respectively. PET imaging showed distribution predominantly to the blood pool, visible as the heart and great vessels in the trunk and limbs, plus diffuse signals in the liver, kidney, spleen, and bone marrow.
The clearance of anti-oxLDL is slightly higher than typical IgG1 antibodies in cynomolgus monkeys. The biodistribution pattern appears to be consistent with an antibody that has no large, rapid antigen sink outside the blood space.
Epidermal growth factor (EGF)-like modules are involved in protein-protein interactions and are found in numerous extracellular proteins and membrane proteins. Among these proteins are enzymes ...involved in blood coagulation, fibrinolysis and the complement system as well as matrix proteins and cell surface receptors such as the EGF precursor, the low density lipoprotein receptor and the developmentally important receptor, Notch. The coagulation enzymes, factors VII, IX and X and protein C, all have two EGF-like modules, whereas the cofactor of activated protein C, protein S, has four EGF-like modules in tandem. Certain of the cell surface receptors have numerous EGF modules in tandem. A subset of EGF modules bind one Ca
2+. The Ca
2+-binding sequence motif is coupled to a sequence motif that brings about β-hydroxylation of a particular Asp/Asn residue. Ca
2+-binding to an EGF module is important to orient neighboring modules relative to each other in a manner that is required for biological activity. The Ca
2+ affinity of an EGF module is often influenced by its N-terminal neighbor, be it another EGF module or a module of another type. This can result in an increase in Ca
2+ affinity of several orders of magnitude. Point mutations in EGF modules that involve amino acids which are Ca
2+ ligands result in the biosynthesis of biologically inactive proteins. Such mutations have been identified, for instance, in factor IX, causing hemophilia B, in fibrillin, causing Marfan syndrome, and in the low density lipoprotein receptor, causing hypercholesterolemia. In this review the emphasis will be on the coagulation factors.
Vitamin K-dependent protein S, a cofactor of the anticoagulant enzyme-activated protein C, has four epidermal growth factor (EGF)-like modules, all of which have one partially hydroxylated Asp (EGF ...1; β-hydroxyaspartic acid) or Asn (EGF 2, 3, and 4; β-hydroxyasparagine) residue. The three C-terminal modules have a typical Ca2+ binding sequence motif that is usually present in EGF modules with hydroxylated Asp/Asn residues. Using the chromophoric Ca2+ chelators Quin 2 and 5,5′-Br2BAPTA, we have now determined the Ca2+affinity of recombinant fragments containing EGF modules 1–3, 1–4, 2–3, and 2–4. EGF modules 1–4 and 2–4 each contains two very high affinity Ca2+-binding sites, i.e. with dissociation constants ranging from 10−10 to 10−8m in the absence of salt and from 10−8 to 10−6m in the presence of 0.15 m NaCl. In contrast, in EGF 1–3 and EGF 2–3, the Ca2+ affinity is 2–4 orders of magnitude lower. EGF 4 thus appears to have the highest Ca2+ affinity, and furthermore it seems to influence the Ca2+ affinity of its immediate N-terminal neighbor EGF 3 by a factor of approximately 230. In addition, EGF 4 seems to influence the Ca2+ affinity of EGF 2 by a factor of approximately 25. The Ca2+ affinity of the binding sites in EGF modules 3 and 4 in fragments EGF 1–4 and EGF 2–4 is 103–105-fold higher than in the corresponding isolated modules, implying important contributions to the Ca2+ affinity of each module from interactions with neighboring modules. This difference is much higher than the approximately 10-fold difference previously found in similar comparisons of EGF modules from fibrillin. However, the modules studied in protein S and fibrillin appear to have the similar Ca2+ligands. The structural basis for the difference in Ca2+affinity is not yet understood.
Protein S is an anticoagulant protein containing a Gla (enclosing gamma-carboxyglutamic acids) module, a TSR (thrombin sensitive region) module, four EGF (epidermal growth factor)-like modules, and a ...SHBG (sex hormone binding globulin)-like region. Protein S is a cofactor to activated protein C (APC) in the degradation of coagulation factors Va and VIIIa but also has APC-independent activities. The function of the fourth EGF module (EGF4) in protein S has so far not been clear. We have now investigated this module through studies of recombinant wild-type protein S and a naturally occurring mutant (Asn217Ser). The mutant has essentially normal APC anticoagulant activity and a previously reported secretion defect. In the wild-type protein, Asn217 is normally beta-hydroxylated. The binding of calcium to wild-type protein S is characterized by four high-affinity binding sites with K(D) values ranging from 10(-)(7) to 10(-)(9) M. Three of these binding sites are located in EGF modules. Using surface plasmon resonance, competition with a calcium chelator, and antibody-based methods, we found that one high-affinity binding site for calcium was lost in protein S Asn217Ser but that the mutation also affected the calcium-dependent conformation of EGF1. We conclude that binding of calcium to EGF4 of protein S, involving Asn217, is important for the maintenance of the structure of protein S. Also, the abolition of binding of calcium to EGF4, related to Asn217, impairs both the structure and function of EGF1.
Calcium-binding epidermal growth factor (EGF)-like modules are found in numerous extracellular and membrane proteins involved in such diverse processes as blood coagulation, lipoprotein metabolism, ...determination of cell fate, and cell adhesion. Vitamin K-dependent protein S, a cofactor of the anticoagulant enzyme activated protein C, has four EGF-like modules in tandem with the three C-terminal modules each harbouring a Ca(2+)-binding consensus sequence. Recombinant fragments containing EGF modules 1-4 and 2-4 have two Ca(2+)-binding sites with dissociation constants ranging from 10(-8) to 10(-5) M. Module-module interactions that greatly influence the Ca(2+) affinity of individual modules have been identified. As a step towards an analysis of the structural basis of the high Ca(2+) affinity, we expressed the Ca(2+)-binding EGF pair 3-4 from human protein S. Correct folding was shown by (1)H NMR spectroscopy. Calcium-binding properties of the C-terminal module were determined by titration with chromophoric chelators; binding to the low-affinity N-terminal site was monitored by (1)H-(15)N NMR spectroscopy. At physiological pH and ionic strength, the dissociation constants for Ca(2+) binding were 1.0x10(-6) M and 4. 8x10(-3) M for modules 4 and 3, respectively, i.e. the calcium affinity of the C-terminal site was about 5000-fold higher than that of the N-terminal site. Moreover, the Ca(2+) affinity of EGF 4, in the pair 3-4, was about 9000-fold higher than that of synthetic EGF 4. The EGF modules in protein S are known to mediate the interaction with factor Xa. We have now found modules 3-4 to be involved in this interaction. However, the individual modules 3 and 4 manifested no measurable activity.
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