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Biomedical subjects

M I Colnaghi

Publications and source records attributed to M I Colnaghi.

At least 127 records · Page 7Linked to original sources
PubMed1991

Anti-drug monoclonal antibodies antagonize toxic effect more than anti-tumor activity of doxorubicin.

Monoclonal antibodies (MAbs) able to bind epitope(s) of drug molecule can interfere with the biologic action of the drug. This is known and already exploited in some instances of practical relevance, as in the reversal of the digoxin effect. Similar antidotal action is exhibited by MAbs reacting with a cytotoxic antibiotic, doxorubicin (DXR), and in such a way as to induce differential neutralization of drug action. Indeed, within certain limits, the cytotoxic action of DXR in vitro as well as in vivo is more effectively neutralized on normal than on tumor cells, with consequent increase in therapeutic index.

Animals↗
PubMed1991

Selection of monoclonal antibodies which induce internalization and phosphorylation of p185HER2 and growth inhibition of cells with HER2/NEU gene amplification.

In order to obtain further information on the biological role of the HER2/neu oncoprotein monoclonal antibodies (MAbs) were produced against the p185 extracellular domain. To immunize the mice and screen the hybridoma supernatants we selected a lung adenocarcinoma cell line (Calu-3), which demonstrated an over-expression of p185HER2 measured as the reactivity with polyclonal rabbit serum to the 14-amino-acid carboxy-terminal-HER2/neu. Two MAbs, designated MGR2 (IgG1) and MGR3 (IgG2), selected for reactivity on Calu-3 and negativity on A43I live cells, the reference target cell for EGF receptor expression, were found to immunoprecipitate a 185-kDa molecule. Immunodepletion experiments with the polyclonal antiserum and cross-competition experiments indicated that the 2 reagents recognized 2 different epitopes located on the p185HER2 molecule. One of the 2 MAbs, MGR3, was found to internalize, induce p185HER2 phosphorylation and inhibit tumor cell growth in vitro. These results indicate that MGR3 is directed against a determinant located in the p185HER2 ligand binding site and may compete with the p185HER2 ligand, but is incapable of inducing a complete mitotic signal.

Animals↗
PubMed1991

Characterization of a monoclonal antibody directed against the epidermal growth factor receptor binding site.

In this work a new monoclonal antibody (mAb), designated MGR1, which recognizes the epidermal growth factor receptor (EGF-R) binding site, is described. The main characteristic of this mAb is its ability to discriminate between cells that express normal levels of EGF-R from cells with overexpression, the detectability threshold by immunocytochemical tests being 5 x 10(4) receptors/cell of 10 microns diameter. MGR1 was found to inhibit EGF binding on the relevant target cells, and vice versa its binding was inhibited by EGF, which indicated that MGR1 recognizes the EGF receptor binding site. MGR1 exerted an inhibitory effect on both the in vitro and in vivo growth of cells with EGF-R overexpression, but had no effect on cells with a normal expression of the receptor. Tumour growth inhibition in athymic mice was also obtained on already implanted tumours. MGR1 therefore seems to be an adequate reagent for the development of immunotherapeutical approaches suitable for the treatment of tumours with EGF-R overexpression.

Animals↗
PubMed1991

Retargeting of human lymphocytes against human ovarian carcinoma cells by bispecific antibodies: from laboratory to clinic.

We have selected a monoclonal antibody (MOv18) reactive with ovarian carcinoma, which exhibits a restricted tumor specificity, a high affinity constant and which recognizes a 38-kDa glycoprotein homogeneously expressed on the cell surface of 90% of human ovarian carcinomas. Localization studies with radiolabelled MOv18 showed that MOv18 could specifically reach ovarian carcinoma cells growing in the peritoneal cavity of nu/nu mice. MOv18 did not mediate antibody-dependent cellular cytotoxicity via Fc and could not be used as a carrier for toxins due to poor internalization of the antigen-antibody complex. Bispecific F(ab')2 antibodies made with MOv18 and an antibody reactive with CD3 were able to redirect the cytotoxicity of peripheral blood lymphocytes (PBL) against ovarian carcinoma cells both in vitro and in vivo in an animal model. The treatment of athymic mice bearing a human ovarian carcinoma intraperitoneally, with human PBL coated with the bispecific F(ab')2, significantly prolonged survival of the animals compared with tumour-bearing untreated and control mice treated with PBL alone. Four ovarian cancer patients have been treated with autologous lymphocytes coated with this bispecific F(ab')2 in a phase I clinical trial. No serious side-effects were observed but patients developed human anti-murine antibodies mainly directed against the idiotype of MOv18. We have now begun phase II clinical trials in ovarian cancer patients.

Animals↗
PubMed1991

Preclinical pharmacokinetics and localization studies of the radioiodinated anti-ovarian carcinoma MAb MOv18.

The in vivo behavior of the monoclonal antibody (MAb) MOv18, with a restricted specificity for human ovarian carcinoma was analyzed on normal and tumor-bearing animals. The pharmacokinetics of the iodine-labeled MAb carried out in BALB/c mice fits an open two-compartment model. The t1/2 alpha was found not to be influenced by the different iodine isotopes used (125I vs 131I) and by the time between labeling procedures and administration. The t1/2 beta were found to be longer after i.p. than i.v. administration and influenced by the time lapse between preparation and administration. A radiolocalization study was carried out in CD1 nu/nu mice bearing i.p. xenotransplant of the human ovarian carcinoma cell line IGROV1. Tumor/non tumor ratios were higher when the time between administration and sacrifice was short and, for 131I-MOv18, with a short interval between labeling and injection. Even if longer half lives were obtained using 125I-MOv18 and i.p. administration a fairly rapid decrease in the values of the percentage of the injected dose per gram of tumor during the time was noted. These data indicate that this MAb could be considered a good candidate for radiotherapeutic approaches.

Animals↗
PubMed1991

Laminin receptors on SCLC cells.

Several studies have suggested a correlation between the metastatic potential and the expression of adhesion molecules and/or their receptors on tumour cell surface membranes. In this study we investigated the expression of functional laminin receptors on small cell lung cancer (SCLC) cells. To this aim we set up an adherence assay to determine the in vitro binding capability of tumour cell lines to laminin. All of the three SCLC lines tested and cells from a short-term SCLC line adhered to laminin in cell culture plates, and the affinity of cell-matrix adhesion proved to be higher than the cell-cell adhesion. This effect was always laminin dose-dependent. On a laminin affinity chromatography column three major proteins could be eluted with EDTA from soluble extracts of SCLC lines. Their molecular weights of 120, 90 and 30 kDa suggested a possible relationship with the integrin family. This putative integrin laminin receptor expressed on SCLC does not react with fibronectin, vitronectin or collagen.

Carcinoma, Small Cell↗
PubMed1991

New developments in breast cancer research.

The last few years have shown an extraordinary development of laboratory and clinical research in breast cancer. The areas which appear particularly important for possible clinical application are many and diversified. In this review we will update the present knowledge regarding four major issues: 1) biologic and molecular tests of prognostic significance in operable breast cancer patients; 2) detection of breast cancer cells in the bone marrow; 3) the endocrine aspects of breast cancer treatment; and 4) the indication of conservative treatments.

Breast Neoplasms↗
PubMed1991

Monoclonal antibodies as carriers for delivering cytotoxic agents.

Because of their high level of specificity monoclonal antibodies can be used as carriers for delivering cytotoxic agents. However they need to have some other features to be usefully used for this purpose. First of all monoclonal antibodies need to be specific for those membrane antigens which are strongly expressed on target cells but absent from normal cells. Secondly it is important to obtain monoclonal antibodies with as a high affinity as possible, and the biodistribution of the molecule recognized by the monoclonal antibody must be considered with the best attention. Chemical treatment of monoclonal antibodies needs to be performed in such a way that neither the antibody nor the toxic agent will result denaturated. Finally, as an alternative to chemically linked immunoconjugates, bispecific antibodies have successfully been used for delivering cytotoxic agents.

Animals↗
PubMed1990

Expression of two antigens defined by monoclonal antibodies in normal, benign and malignant human mammary tissues.

We examined the reactivity of two monoclonal antibodies (MAbs), MBrI and MBr8, on sections from normal breast tissues, benign lesions, primary infiltrating carcinomas and distant breast cancer metastases and compared the expression of the recognized antigens (CaMBr1 and CaMBr8 respectively) in these different normal and pathologic conditions. The expression of both antigens was found to significantly decrease in the neoplastic tissues, in comparison to normal breast tissue (34% vs 61% for MBr1 and 52% vs 86% for MBr8; p less than 0.001 for both). Atypical epithelial hyperplasia was found to be reactive on the same level (31%) of the tumors when tested with MBr1, whereas its reactivity was similar to that of normal tissues (78%) when MBr8 was used. Nonatypical epithelial hyperplasia showed the same reactivity with both MAbs (positive staining on about 50% of the cells). 65% of the "in situ" ductal carcinoma cases was MBr1-positive, whereas 50% was MBr8-positive; these values, when compared with the reactivity on normal glands, were significantly lower for MBr8, but not for MBr1. When testing sections from premenopausal women who had biopsies performed on different days during their menstrual cycle a correlation was found between the expression of CaMBr1 in normal breast epithelial cells and the stimulatory phase of the cycle. These findings suggest that both antigens are typical of normal breast and their expression could possibly decrease in pathologic tissues.

Antibodies, Monoclonal↗
PubMed1990

Fractionation of the ribosome inactivating protein preparations with triazine dyes.

Aspergillins are ribosome-inactivating proteins (RIPs), isolated from several strains of Aspergillus. The interaction between Cibacron Blue F3GA and two members of this family, alpha sarcin and mitogillin, and other RIPs of type I, was studied. Alpha sarcin retention depended on pH and ionic strength. By chromatography on Affi-Gel Blue in mild experimental conditions, mitogillin and PAP-I did not interact with the dye, whereas 40% of alpha sarcin and 70-90% of briodin, RTA and gelonin were recovered in the bound fraction. In all cases, the major fraction showed a higher toxicity level in protein synthesis inhibition assays. The unbound alpha sarcin, conjugated with the anti-ovarian carcinoma monoclonal antibody MOv17, showed on OVCA 432 a cytotoxicity which was 900 times higher than that exerted by the alpha sarcin alone.

Antibodies, Monoclonal↗
PubMed1990

The Ca-MOv18 molecule, a cell-surface marker of human ovarian carcinomas, is anchored to the cell membrane by phosphatidylinositol.

The structure of the 38 kD cell surface glycoprotein identified by the monoclonal antibody MOv18 and specifically expressed by human ovarian carcinomas has been investigated at a molecular level. The ovarian carcinoma cell line IGROV-1, which expresses high levels of Ca-MOv18, was treated with the phosphatidylinositol-specific phospholipase C from B. thuringiensis. The phospholipase C specifically released most of the Ca-MOv18 molecules as shown by flow cytometric analysis of the treated cells and by radioimmunometric assays of the corresponding supernatants. Consistent with the known structure of other phosphatidylinositol-linked molecules, Ca-MOv18 was biosynthetically labeled by [3H]ethanolamine and the labeled molecules were immunoprecipitated from the supernatant fo the phospholipase C treated cells. Evidence that Ca-MOv18 is anchored to the cell membrane via phosphatidylinositol may prove to be relevant in current investigations regarding the biological and clinical significance of this tumor marker.

Antibodies, Monoclonal↗
PubMed1990

MOv18 monoclonal antibody in diagnostic applications: capability to recognize the histotype of the original tumor.

Cells from 52 ascitic fluids and 28 abdominopelvic cavity washings, obtained from 46 ovarian cancer patients, 17 patients bearing malignancies of non ovarian sites and 17 patients with non-malignant ovarian diseases, were tested using 2 methods: traditional cytology and monoclonal antibody immunofluorescence. The immunologic test using the MOv18 MAb, raised against ovarian carcinoma, revealed immunoreactive cells in 83% of the 36 cytologically positive fluids and in one of the 8 negative fluids from ovarian carcinoma patients and in 18% of the 17 fluids from patients with non-malignant ovarian disease. Forty six cytologically positive ascitic fluids from malignant patients were analyzed in order to evaluate the ability of this MAb to identify the histotype of metastatic cells. Ninety-three percent (26/28) of the effusions from nonmucinous ovarian carcinomas contained MOv18-positive cells, whereas no reactive cells were found in cytologically malignant fluids from patients with ovarian tumors of other oncotypes or with carcinomas of non-ovarian origin. The MOv18 reagent, used as an adjuvant in cytological analysis, can help in the identification of the histotype of metastatic cells of unknown origin.

Adenocarcinoma↗
PubMed1990

Use of monoclonal antibody MBr1 to detect micrometastases in bone marrow specimens of breast cancer patients.

Bone marrow specimens obtained from 121 breast cancer patients immediately after surgery were examined by an immunofluorescence method with monoclonal antibody MBr1 to detect tumour cells undetectable by other diagnostic procedures. 80 women were node-negative and 41 node-positive. In no case could conventional histology demonstrate tumour cells, whereas MBr1 was positive in 20 (16.5%) of the 121 cases. No difference was observed in MBr1 positivity between node-negative and node-positive cases (17% vs. 15%). With regard to clinical outcome (median follow-up 48 months) 27 women relapsed, including 6 of 20 MBr1-positive and 24 of 101 MBr1-negative patients. First distant metastases or death from progression of disease were taken as end-points. Multivariate analysis showed that the additional contribution of MBr1 positivity, after making allowance for other prognostic factors, was negligible.

Adult↗
PubMed1990

Evaluation of the immunoreactive fraction of an anti-tumour monoclonal antibody.

Over a period of approximately 1 year, the immunoreactivity of the anti-ovary carcinoma MAb MOv18 was evaluated after radiolabelling with 125I on two different ovarian carcinoma cell lines, OvCa432 and IGROV1. A high variability of the immunoreactive values was observed by analysing different preparations of radiolabelled MOv18 (from 12 to 21% on OvCa432 and from 22 to 56% on IGROV1) and by using the same radiolabelled preparation (12% on OvCa432 and 51% on IGROV1). Since the variability could be due to the target cells, we set up an alternative binding assay using the anti-idiotypic MAb anti-Id18.1 directed against a private idiotype closely associated with the MOv18 paratope. Three different experiments carried out with the anti-idiotypic MAb gave reproducible results with an immunoreactive range from 71 to 83%. A direct comparison between the reactivity of the same 125I-MOv18 preparation on anti-Id18.1 and on IGROV1 confirmed the higher value of the immunoreactive fraction estimated on the more homogeneous anti-idiotypic reagent (71%), rather than on the tumour cells (56%). These data suggest that anti-idiotypic MAbs could represent suitable reagents for the evaluation of the immunoreactivity of an antibody preparation after radiolabelling and before in vivo administration.

Antibodies, Anti-Idiotypic↗
PubMed1989

In vivo and in vitro growth of SCLC cells derived from biopsies.

In order to increase the availability of SCLC cells derived from biopsies, in vivo and in vitro growth methods were investigated. The cells grown in both conditions were periodically monitored for reactivity with 2 monoclonal antibodies (MAbs): MLuC1 directed against SCLC cells and IM1 which recognizes the class II antigen on activated lymphocytes and macrophages. About 50% of the 28 analyzed SCLC specimens were found to proliferate in one or both systems. The in vitro-grown cells exhibited the same heterogeneity found in the original cell suspensions and moreover, in some cases only normal cells were recovered after several in vitro passages. From the subcutaneous transplanted tumors a large number of MLuC1-positive tumor cells could easily be recovered, thus indicating the validity of the in vivo methodology. The MBr1 MAb, directed against an epithelial antigen, was found to react with about 50% of the 26 tested tumors, mainly those which demonstrated in vivo and/or in vitro growth capacity. These data suggest that only some tumors, presumably with peculiar biological characteristics, can efficiently grow in these artificial systems.

Adult↗
PubMed1989

Immunohistochemical reactivity of a monoclonal antibody prepared against human ovarian carcinoma on normal and pathological female genital tissues.

The reactivity profile of the monoclonal antibody (MAb) MOv18, raised against a poorly differentiated ovarian carcinoma specimen, was studied on normal tissues and tumors from the female reproductive system and on the kidney, which like the oviducts, vagina and uterus, also derives from the intermediate mesoderm. The obtained results indicate that MOv18 recognizes an epitope present on the normal epithelium of the oviducts, on 14-week old fetal kidney and, focally, on proximal and distal tubules of normal adult kidney. A strong reactivity was found on ovarian carcinomas, on invasive squamous carcinomas of the cervix and on endometrial carcinomas and hyperplasias. The antigen recognized by MOv18 (CaMOv18) therefore seems to be an epithelial cell marker associated with intermediate mesoderm differentiation, which can be derepressed during the neoplastic transformation of the ovary and the uterus.

Adult↗
PubMed1989

Relationship between CaMBr1 expression and tumor progression in small cell lung carcinomas.

In order to study the possible relationship between antigenic phenotype and tumor progression, 63 small cell lung carcinomas (SCLC) biopsies derived from primary or metastatic tumors were tested by immunofluorescence and immunoperoxidase techniques with an anti-carcinoma monoclonal antibody designated MBr1. Primary tumors were found to be less reactive with MBr1 than the local and distant metastatic lesions (57% versus 75% and 89% positivity respectively). A life table analysis on the tested cases indicated an inverse association between the expression of the marker recognized by the MBr1 MAb (CaMBr1) and overall survival (p less than 0.01): patients with MBr1-positive tumors showed a shorter survival time in comparison to patients whose tumors did not express the marker. The same correlation between survival and CaMBr1 expression was found even when only the 31 cases of early stage disease patients were considered (p less than 0.05). Different tumor aggressiveness or resistance to therapy of MBr1-positive tumors could be responsible for the shorter survival time of the patients.

Antibodies, Monoclonal↗