Biomedical subjects

Claudia De Lorenzo

Publications and source records attributed to Claudia De Lorenzo.

6 recordsLinked to original sources

PubMed2007

Intracellular route and mechanism of action of ERB-hRNase, a human anti-ErbB2 anticancer immunoagent.

Human anti-ErbB2 immunoRNase with Erbicin fused to HP-RNase (ERB-hRNase) is a fully human immunoRNase made up of human pancreatic RNase fused to a human anti-ErbB2 scFv. It binds selectively with high affinity to ErbB2-positive cells, and specifically inhibits their proliferation, in vitro and in vivo. An investigation of its mechanism of action and its intracellular destination has revealed that ERB-hRNase depends on its RNase activity for cytotoxic action; it reaches the cytosol directly from the endosomal compartment; it is inhibited by the cytosolic RNase inhibitor (cRI), but the levels that ERB-hRNase reaches in the cytosol neutralize cRI, thus inducing cell death by apoptosis.

Antineoplastic Agents↗

PubMed2006

Fibrinogen concentrate reverses dilutional coagulopathy induced in vitro by saline but not by hydroxyethyl starch 6%.

Severe bleeding often induces coagulopathy via loss, consumption, and dilution of clotting factors and platelets. The aims of our in vitro study were to characterize the influence of progressive hemodilution with either NaCl 0.9% or hydroxyethyl starch (HES) 6% on blood clot formation and to analyze the effect of substitution of fibrinogen and platelets on dilutional coagulopathy. Whole blood samples drawn from 8 volunteers were diluted from 20% to 80% of the sample volume with both diluents separately. Clot formation was measured by thrombelastography. At a 60% dilution, either fibrinogen and/or platelets were added to the samples. Clot firmness became critical after 40% dilution with HES 6% but not until 60% dilution with NaCl 0.9%. When platelet function was blocked, fibrin polymerization was severely impaired after 20% dilution with HES 6%, whereas such an effect was only seen after 80% dilution with NaCl 0.9%. The addition of fibrinogen reconstituted the clot firmness in the presence of NaCl 0.9%, but this had only a minor effect after dilution with HES 6%. Platelets alone or in addition were not able to improve clot firmness to a clinically relevant extent. Dilutional coagulopathy induced by crystalloids can, in vitro, be effectively reversed by supplementation of fibrinogen. In contrast, HES molecules interfere with fibrin polymerization and, thus, administration of fibrinogen after dilution with HES 6% failed to significantly improve clot firmness.

Analysis of Variance↗

PubMed2005

Biological properties of a human compact anti-ErbB2 antibody.

ErbB2 is a prognostic factor and target of therapy for many carcinomas. In contrast with the other ErbB receptors, ErbB2 lacks a soluble direct ligand, but it is the preferred co-receptor for the ErbB family members, forming heterodimers with more potent and prolonged signalling activity than that of homodimers. We recently produced a new anti-ErbB2 antibody, Erb-hcAb, by fusion of Erbicin, a human, anti-ErbB2 scFv, selectively cytotoxic to ErbB2-positive cells, and a human Fc domain. This fully human antitumour antibody represents a compact version of an IgG1, with the cytotoxicity of the scFv moiety on target cells, combined with the ability of the Fc moiety to induce both antibody- and complement-dependent cytotoxicity. Here, we describe the main properties of Erb-hcAb, using as a reference Herceptin, an anti-ErbB2 humanized monoclonal currently employed in clinical immunotherapy. We found that both bivalent Erb-hcAb and Herceptin increase receptor phosphorylation and downregulation, whereas monovalent Erbicin does not. These results correlate with the finding that Erb-hcAb is capable of inducing apoptosis and inhibiting cell cycle progression in ErbB2-positive cells. Its powerful in vitro antitumour action matched that observed in vivo in experiments with human ErbB2-positive tumour xenografts established in athymic mice. Finally, Erb-hcAb displays a glycosylation profile virtually superimposable to that of a human IgG. These findings suggest that Erb-hcAb is a very promising new agent for the immunotherapy of carcinomas that overexpress the ErbB2 receptor.

Animals↗

PubMed2004

A fully human antitumor immunoRNase selective for ErbB-2-positive carcinomas.

We report the preparation and characterization of a novel, fully human antitumor immunoRNase (IR). The IR, a human RNase and fusion protein made up of a human single chain variable fragment (scFv), is directed to the ErbB-2 receptor and overexpressed in many carcinomas. The anti-ErbB-2 IR, named hERB-hRNase, retains the enzymatic activity of the wild-type enzyme (human pancreatic RNase) and specifically binds to ErbB-2-positive cells with the high affinity (K(d) = 4.5 nm) of the parental scFv. hERB-hRNase behaves as an immunoprotoxin and on internalization by target cells becomes selectively cytotoxic in a dose-dependent manner at nanomolar concentrations. Administered in five doses of 1.5 mg/kg to mice bearing an ErbB-2-positive tumor, hERB-hRNase induced a dramatic reduction in tumor volume. hERB-hRNase is the first fully human antitumor IR produced thus far, with a high potential as a poorly immunogenic human drug devoid of nonspecific toxicity, directed against ErbB-2-positive malignancies.

Amino Acid Sequence↗

PubMed2002

A new RNase-based immunoconjugate selectively cytotoxic for ErbB2-overexpressing cells.

We report a new tumor-directed immunoRNase, a chimeric protein made up of an antibody fragment (single-chain Fv fragment) directed to ErbB2, a cell surface receptor, and a non-toxic, human ribonuclease, which upon cell internalization becomes cytotoxic. The immunoRNase is active as a ribonuclease, specifically binds and selectively kills ErbB2-positive cells. ErbB2 is one of the most specific tumor-associated antigens identified so far, overexpressed on tumor cells of different origin. Its choice as target antigen and that of a non-toxic, human RNase as the killer moiety makes this immunoRNase a new, potentially attractive anticancer agent.

Antigens, Neoplasm↗

PubMed2002

A new human antitumor immunoreagent specific for ErbB2.

PURPOSE: Our aim was to isolate a novel human mini-antibody(scFv) that specifically targets ErbB2-positive cancer cells. ErbB2, a tyrosinekinase receptor, is overexpressed in clinically significant tumors, such as breast, ovary, and lung carcinomas. In normal tissues, it is expressed only in certain epithelial cell types. EXPERIMENTAL DESIGN: A large phagemid library (Griffin.1 library) of human scFv was used for the isolation of the ErbB2-specific scFv. A very effective strategy was developed for the isolation, consisting in a double subtractive selection, the use of two different combinations of "positive," i.e., ErbB2-bearing, and "negative" cell lines. RESULTS: Here we report the isolation of the first human anti-ErbB2 mini-antibody endowed with antitumor action. Both in its soluble and phage format, it binds specifically to ErbB2, inhibits its autophosphorylation, is internalized by target cells, and exerts a strong and specific antiproliferative action on ErbB2-positive target cells. A correlation was found between the extent of this antiproliferative effect and the expression levels of ErbB2 on target cells, with a strong cytotoxicity for hyper-expressing cells, such as SKBR3, in which apoptosis was evidenced. CONCLUSIONS: This scFv is a potentially effective immunoreagent for diagnostics and therapeutics of certain cancers, both as a readily diffused molecule in solid tumors and as an essential asset for the construction of fully human anticancer drugs.

Animals↗