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Biomedical subjects

M I Colnaghi

Publications and source records attributed to M I Colnaghi.

At least 73 records · Page 4Linked to original sources
PubMed1995

Unidirectional potentiation of binding between two anti-FBP MAbs: evaluation of the involved mechanisms.

The monoclonal antibody MOv19 directed to a folate binding protein shows temperature-dependent potentiation of binding of the noncompeting monoclonal antibody MOv18 to the relevant antigen, but the mechanism involved in this phenomenon had remained unclear. Use of chimeric versions of both monoclonal antibodies and the F(ab')2 and Fab fragments of MOv19 revealed an increment in MOv18 binding in all combinations irrespective of the origin of the Fc portion of the monoclonal antibody. The potentiating effect of bivalent MOv19 fragments on 125I-MOv18 binding was similar to that of the entire monoclonal antibody and occurred at saturating concentrations of both reagents at which monovalent binding prevails. Similarly, the monovalent fragment also induced a significant increase in MOv18 binding. However, the potentiation occurred only at very high concentrations of antibody fragment. Homologous inhibition was drastically reduced using MOv19 Fab fragment, suggesting a low binding stability of the monovalent reagent. Immunoblotting analysis and binding in the presence of exogenous purified folate binding protein indicated a cross-linking between soluble and cell surface molecules mediated by the bivalent monoclonal antibodies. The extent of the increase in MOv18 binding at 0 degrees C with high amounts of exogenous folate binding protein was lower than that obtained at 37 degrees C in the absence of added molecule. Release of 125I-MOv18 from the cell surface was significantly higher in the absence of MOv19 than in its presence.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1995

Prognostic significance of laminin production in relation with its receptor expression in human breast carcinomas.

Laminin is a basement membrane glycoprotein whose expression has been widely related to cancer progression. Laminin production by primary breast carcinomas was investigated using immunohistochemistry on archival specimens from a retrospective series with long term follow-up. Laminin production was found to be independent of the clinical and pathological variables analyzed, whereas a statistically significant direct association with the expression of the laminin receptor and a negative association with the differentiation-related antigen Ca-MBr8 were observed. Survival analysis indicated that laminin positivity by itself has no prognostic significance. However, when analyzed together with the laminin receptor expression, laminin was associated with a good prognosis in receptor-negative tumors and with the worst prognosis in receptor-positive tumors.

Breast Neoplasms↗
PubMed1995

Preclinical evaluation of the ribosome-inactivating proteins PAP-1, PAP-S and RTA in mice.

In a preclinical mouse model the plant ribosome-inactivating proteins (RIPs) pokeweed antiviral proteins PAP-1, and PAP-S and ricin A-chain (RTA) induced a pathological elevation of serum concentrations of glutamate pyruvate transaminase (GPT) and blood urea nitrogen (BUN) and had a significant immunosuppressive effect on B- and T-lymphocytes. The present analysis and comparison of the biodistribution and systemic/organ toxicity associated with RIP injection suggest a possible in vivo mechanism of action of PAP-1 and PAP-S and identify several limitations in the clinical use of these two toxins and RTA. When administered intravenously, PAP-1 and PAP-S consistently accumulated in kidneys and induced histologically documented damage to kidney and liver, with a LD50 of 3.3 mg/kg and 1.6 mg/kg for PAP-1 and PAP-S, respectively. In mice injected with PAP-S after chlorpromazine (CPZ) administration, GPT levels returned to normal between 24 and 72 h after toxin injection, while the BUN levels remained elevated. Mortality of the animals was delayed but all mice eventually succumbed. All the three toxins inhibited the expansion of anti-sheep red blood cells (SRBC) antibody-forming cells and the production of anti-SRBC antibody levels, although PAP-S showed the most potent activity. Despite the immunosuppressive activity, all toxins were highly immunogenic.

Alanine Transaminase↗
PubMed1995

In vitro and in vivo stability and anti-tumour efficacy of an anti-EGFR/anti-CD3 F(ab')2 bispecific monoclonal antibody.

The in vitro and in vivo stability and anti-tumour efficacy of the anti-EGFR/anti-CD3 bispecific monoclonal antibody (biMAb), M26.1, were analysed. The interaction of the intact biMAb with Fc receptor I (Fc gamma RI) present on human leucocytes was not observed when the antibody was used as an F(ab')2 fragment. A CD8+ T-cell clone coated with M26.1 F(ab')2 was as effective as the intact biMAb in inducing IGROV1 target cell lysis when tested in a 51Cr-release assay. Variable levels of reduction of F(ab')2 to monovalent F(ab') were observed upon incubation with human ovarian cancer ascitic fluid (OCAF) or with human glioblastoma cavity fluid (GCF), but not with mouse or human sera. Activated lymphocytes coated with F(ab')2 and incubated in vitro with GCF or OCAF for 24 and 48 h respectively maintained their targeting. Thus, the F(ab')2, when present as a soluble molecule, but not when bound to T cells, might lose some functional activity as a consequence of partial reduction to F(ab'). In normal mice, M26.1 F(ab')2 retained full cytotoxic activity in the circulation, and clearance values were similar to those obtained with parental and other MAb F(ab')2. Treatment of IGROV1 tumour-bearing mice with activated human lymphocytes coated with the M26.1 F(ab')2 significantly prolonged survival of the animals compared with tumour-bearing untreated and control mice treated with lymphocytes or F(ab')2 alone. Together, these results suggest the clinical usefulness of bispecific M26.1 F(ab')2 as a targeting agent for local treatment of tumours such as glioma and ovarian cancers that express variable levels of epidermal growth factor receptor (EGFR).

Animals↗
PubMed1995

Bispecific antibody targeted T cell therapy of ovarian cancer: clinical results and future directions.

The high frequency of relapse after induction chemotherapy in advanced ovarian carcinoma patients calls for new therapeutic modalities. Retargeted T cell-mediated lysis can be achieved using the bispecific antibody (BsmAb) OCTR, directed to CD3 on T cells and to the folate receptor on ovarian carcinoma cells. Twenty-eight patients with limited intraperitoneal disease after first-line therapy entered a phase II study. They received two i.p. 5 day cycles of activated PBMC retargeted with OCTR. Despite unfavorable tumor characteristics, 7 of 26 patients (27%) showed complete or partial intraperitoneal responses with strict surgicopathologic evaluation. In most cases, the disease relapsed outside the peritoneal cavity, and in 1 case complete intraperitoneal response was accompanied by progression in retroperitoneal lymph nodes. The morbidity was mild to moderate and transient. Combination of i.v. and i.p. administration of OCTR-retargeted lymphocytes will possibly lead to extraperitoneal cure. Ongoing clinical studies indicate that the i.v. infusion of up to 8 x 10(8) OCTR-retargeted T lymphocytes does not induce a higher toxicity than the i.p. treatment. To avoid PBMC preactivation, new approaches for delivering accessory signals are under investigation. Preliminary results indicate that nonactivated PBMC retargeted by OCTR in the presence of an anti-CD28 monoclonal antibody (mAb) are able to significantly inhibit tumor growth.

Antibodies, Bispecific↗
PubMed1994

Chimeric murine-human antibodies directed against folate binding receptor are efficient mediators of ovarian carcinoma cell killing.

The MOv18 (gamma 1, kappa) and MOv19 (gamma 2a, kappa) murine monoclonal antibodies (MAbs) recognize different epitopes on the human folate binding receptor which is overexpressed on 90% of nonmucinous epithelial ovarian tumors. A chimeric murine-human (human gamma 1, kappa) version of both antibodies was constructed and expressed. The genes encoding the murine heavy and light chain variable regions of the MOv18 and MOv19 MAbs were cloned from the parental hybridomas, fused with genes encoding the human heavy (gamma 1) and light (kappa) chain constant regions, respectively, and expressed in the SP2/0 murine myeloma cell line. Using human peripheral blood mononuclear cells as effector cells and conditions that provide for maximum lysis (effector target = 50:1, saturating antibody concentration), the murine MOv18 MAb (IgG1) mediated variable levels of specific cytolysis of the target ovarian cancer cell line IGROV1. In contrast, the chimeric MOv18 MAb mediated higher and more consistent lysis even at a 10-100-fold lower antibody concentration. The murine MOv19 MAb (IgG2a) mediated specific lysis of IGROV1 cells, and the chimeric version of this antibody mediated an amount of lysis at least equal to that mediated by its murine counterpart. A comparison of the ED50 values obtained for the murine MOv19 and chimeric MOv19 antibodies indicates that the chimeric MOv19 MAb was 3 to 10 times more potent than the murine MOv19 antibody. In addition, the ED50 values obtained for the chimeric MOv18 and chimeric MOv19 MAbs were similar, indicating that these MAbs are equally potent. The level of maximal lysis obtained was dependent on the number of target molecules/cell; the same high level of lysis mediated by cMOv18, MOv19, and cMOv19 was observed with both IGROV1 and OvCA432 target cells. However, only low levels of lysis were obtained when the SW626 cell line, which expresses 1 x 10(4) folate binding protein sites/cell, was used as a target. An equimolar mixture of the chimeric MOv18 and MOv19 MAbs was no more effective in the mediation of lysis than an equivalent amount of either chimeric MAb alone. These data suggest that the folate binding receptor is expressed on IGROV1 cells at a density sufficient to provide for optimal levels of antibody-mediated lysis using a single chimeric antibody directed at the folate binding receptor.

Animals↗
PubMed1994

The LFA-1/ICAM cell adhesion pathway is involved in tumor-cell lysis mediated by bispecific monoclonal-antibody-targeted T lymphocytes.

We investigated the role of the LFA-1/ICAM, VLA-4/VCAM-1 and CD2/LFA-3 adhesion pathways in the cytolysis of tumor cells mediated by an anti-EGF-R/anti-CD3 bispecific monoclonal antibody (biMAb). The biMAb induced efficient lysis of EGF-R+ tumor cells (A431, HT-29, IGROV-1 and MDA-MB468) by cytotoxic T lymphocytes (CTL) cultured in IL-2. Pretreatment of effector cells by anti-LFA-1 alpha (CD11a) and anti-LFA-1 beta (CD18) MAbs significantly inhibited cytolysis of all types of EGF-R+ tumor cells, while anti-CD2 and anti-VLA-4 MAbs were virtually ineffective. We investigated the expression of adhesion-molecule counter-receptors on tumor target cells by indirect immunofluorescence. HT-29, A431 and MDA-MB 468 tumor cells expressed an ICAM-1+2-3- VCAM-1- LFA-3+ phenotype, while IGROV-1 was ICAM-1-2+3- VCAM-1- LFA-3+. Pre-treatment of A431, HT-29 and MDA-MB468 with anti-ICAM-1 MAb inhibited cytolysis, further supporting the functional involvement of the LFA-1/ICAM adhesion pathway in biMAb-targeted tumor-cell lysis. In addition, treatment of target cells with TNF alpha or IFN gamma for 24 hr increased the expression of ICAM-1 in HT-29, A431 and MDA-MB468 (ICAM-2 was induced on IGROV-1) and also enhanced the sensitivity of these target cells to biMAb-targeted cytotoxicity. These data suggest that up-regulation of ICAM-molecule expression by inflammatory cytokines may increase susceptibility of tumor cells to biMAb-targeted lysis. Anti-LFA-1 MAbs did not significantly inhibit the formation of conjugates between biMAb-coated T lymphocytes and tumor cells. Co-aggregation of LFA-1 molecules with biMAb-bound CD3 molecules resulted in a more sustained and prolonged increase in the intracellular concentration of free Ca++ in CD8+ cultured CTL lines. These findings indicate that in T cells targeted by anti-CD3/anti-TAA biMAb LFA-1 may act as a co-receptor molecule which enhances signal transduction through the CD3/TCR complex.

Antibodies, Bispecific↗
PubMed1994

Antigenic and immunogenic mimicry of the HER2/neu oncoprotein by phage-displayed peptides.

To recover peptides that antigenically and immunogenically mimic the p185HER2 oncoprotein, we selected the phage-peptide libraries pVIII-9aa and pVIII-9aa. Cys using murine monoclonal antibodies (mAb) MGr2 and MGr6, directed against two distinct epitopes of the p185HER2 extracellular domain. Phage-displayed peptides containing consensus amino acid motifs were recovered and shown to compete specifically for mAb binding on tumor cells that overexpress p185HER2. The deduced amino acid sequence of the peptides suggests that both epitopes defined by the mAb on p185HER2 are discontinuous and that hydrophobic interactions are involved in binding with the mAb. A phage clone displaying the GPLDSLFAQ peptide elicited a specific immune response against the p185HER2 in BALB/c mice, demonstrating that this phage-displayed peptide represents an immunological equivalent of the MGr2 epitope on p185HER2 and might be used as a substitute for this oncoprotein in in vitro and in vivo immunological studies.

3T3 Cells↗
PubMed1994

Laminin receptor expression and function in small-cell lung carcinoma.

Interactions between tumor cells and laminin or other components of the extracellular matrix are thought to play a role in tumor invasion and metastasis. To analyze these interactions, we examined the expression of 5 types of laminin receptors on 11 cell lines derived from the highly malignant and metastatic tumor small-cell lung cancer (SCLC). The integrins VLA-1, VLA-3, VLA-6 and the 67 KDa monomeric receptor were expressed at various levels, whereas the VLA-2 receptor was absent on the cell lines. Only one cell line expressed none of these laminin receptors. All cell lines co-expressed alpha 6 beta 1 (VLA-6) and the 67-kDa molecule, the only receptors specific for laminin. Analysis of the ability of SCLC cells to bind radiolabeled laminin and to adhere to laminin substrata revealed a correlation between these 2 parameters and the expression of VLA-6 and the 67-kDa monomeric receptor. Cell adhesion was mediated by alpha 6 beta 1, as indicated by inhibition of adhesion using an anti-VLA-6 monoclonal antibody (MAb). Both VLA-6 and the monomeric receptor were up-regulated in vitro by laminin.

Antibodies↗
PubMed1994

Colocalization of the p185HER2 oncoprotein and integrin alpha 6 beta 4 in Calu-3 lung carcinoma cells.

Anti-p185HER2 monoclonal antibodies often show intense reactivity with the basement membrane of tumor cells that overexpress the HER2/neu gene product (p185HER2). To evaluate a possible interaction between p185HER2 and adhesion molecules or their receptors, the polarity of p185HER2 was tested in lung carcinoma cell line Calu-3, which overexpresses this protein, in cultures grown as confluent monolayers or as aggregates. MAb immunostaining patterns indicated that p185HER2 is concentrated on the baso-lateral membrane of cells and that it colocalizes with the integrin alpha 6 beta 4 at the cell-cell junctions where laminin is also found. The same membrane region showed intense reactivity with antiphosphotyrosine antibodies. Furthermore, integrin clustering induced by the specific antibody was accompanied by the clustering of p185HER2, as indicated by immunoelectron microscopy, and by a subsequent increase in p185HER2 tyrosine phosphorylation. Treatment with exogenous laminin also resulted in increased basal levels of p185HER2 phosphorylation. These data suggest a physical interaction between the integrin and the oncoprotein that might be functionally relevant in directly controlling the tyrosine phosphorylation of the catalytic domain of p185HER2.

Antibodies, Monoclonal↗
PubMed1994

Modulation of drug-induced cytotoxicity by a bispecific monoclonal antibody that recognizes the epidermal growth factor receptor and doxorubicin.

A hybrid hybridoma secreting a bispecific hybrid mAb (bsmAb), which recognizes both the epidermal growth factor receptor (EGF-R) and the drug doxorubicin, was produced by somatic hybridization of two hybridomas. The bsmAb obtained was able to retarget doxorubicin cytotoxicity in vitro specifically on EGF-R-positive cells exerting at the same time an antidotal effect on cells that did not overexpress the EGF-R. Distribution studies in mice indicate that the bsmAb selectively delivers the drug to tumour cells and modifies doxorubicin biodistribution with a statistically significant decrease of drug concentration in the intestine, which is the main target of early anthracycline toxicity. In keeping with this finding is the remarkable antidotal activity exerted by bsmAb in mice treated with doxorubicin, which is proved by retardation in loss of body weight and mortality. The effectiveness on tumour growth of the mAb followed by the administration of doxorubicin appears to be equal to that of the drug alone; however, the bsmAb exerts a remarkable antidotal activity.

Animals↗
PubMed1994

Effect of a bifunctional monoclonal antibody directed against a tumor marker and doxorubicin on the growth of epidermoid vulvar carcinoma grafted in athymic mice.

Even though the first monoclonal antibodies (MAbs) directed against tumor cells were produced 15 yr ago, the therapeutic application of immunoconjugates is still at the beginning. This is principally because of the enormous work that is required for the development of completely new therapeutic tools. An alternative could be to only use MAbs to improve conventional treatment such as chemotherapy. To this aim, a MAb directed against doxorubicin (DXR) was produced. DXR is an anthracycline antibiotic of which the clinical usefulness in cancer chemotherapy is limited by serious side effects, such as cardiomyopathy, bone marrow depression, and gastrointestinal tract mucositis. This toxicity was found to be reduced by treatment with the antidrug MAb, as shown by reduction in body weight loss and mortality of experimental mice. To improve the DXR therapeutic index, a bifunctional hybrid MAb (DOXER2), capable of simultaneously recognizing DXR and the epidermal growth factor (EGF) receptor, was produced. This reagent was found in vitro to increase the drug toxicity on the epidermoid carcinoma cell line A431, which overexpresses the EGF-R and, at the same time, to reduce DXR cytotoxicity on EGF-R negative cells. The effect of DOXER2 on the DXR biodistribution in vivo was also investigated. In mice previously injected ip with the DOXER2, the uptake of the drug, in comparison to the control group, was found to be reduced in the intestine and in myocardial tissue, and significantly increased in the tumor.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Folate binding protein distribution in normal tissues and biological fluids from ovarian carcinoma patients as detected by the monoclonal antibodies MOv18 and MOv19.

Folate-binding proteins (FBP), which are molecules relevant in folate metabolism, are overexpressed in ovarian carcinomas, as detected by the monoclonal antibodies (MAb) MOv18 and MOv19, which recognise two different epitopes of the gp38/FBP. In this paper, features of the FBP such as the distribution on normal tissues and the release in biological fluids of normal and tumour origin have been investigated. Immunohistochemical analyses on frozen sections of normal tissues showed the presence of the gp38/FBP on some epithelia. The reactivity of both the MAb on Fallopian tubes was intense and comparable to that observed on ovary carcinoma sections. The kidney, bronchial glands, alveolar epithelium of the lung, oesophagus, stomach, pancreas, breast and thyroid showed different levels of staining. By MOv18/MOv19 double-determinant immunoradiometric assay (DDIRMA), the gp38/FBP was found in soluble form in ascitic fluid, serum and urine of nude mice in which the human ovary carcinoma cell line IGROV1 grew as ascitic carcinomatosis. In human biological fluids, the gp38/FBP was detected in ascites of 60% of ovarian carcinoma patients, and in 29% of those with other carcinomas, but not in patients with non-epithelial tumours or with other non-tumoral pathologies. The mean serum arbitrary units (a.u.)/ml values of ovary carcinoma patients were significantly different to those of healthy donors or patients with endometriosis (P < 0.005 and P < 0.01, respectively), but not when compared to the sera of lung carcinoma patients. In addition, the sensitivity of DDIRMA was poor, since only 24% of the ovary carcinoma patients were positive with this assay. When a restricted number of cases selected for the presence of tumour cells in the ascites was examined, the percentage of DDIRMA-positive sera and ascites rose to 41 and 94%, respectively. In the urine, a strong reactivity was observed in the samples of both normal and tumour origin.

Animals↗
PubMed1994

Immunodetection of bone marrow micrometastases in breast carcinoma patients and its correlation with primary tumour prognostic features.

Methods such as immunohistochemistry that have enhanced the detection of carcinoma cells in bone marrow aspirates appear to be useful in identifying patients with aggressive tumours. To detect epithelial cells in bone marrow aspirates from breast carcinoma patients, we used a pool of five different monoclonal antibodies (MAbs), which recognise 100% of breast carcinomas, together with the alkaline phosphatase method on cytospun cells obtained from sternum and iliac crest. Primary tumours were also analysed for the expression of the c-erbB-1 and c-erbB-2 oncogene products, and of two differentiation-related markers and laminin receptors. Immunoreactive cells were detected in the bone marrow of 62 of the 197 patients tested (31%) without any correlation with clinical parameters such as tumour size or lymph node metastasis, whereas a significant (P < 0.01) correlation was found with enhanced monomeric laminin receptor expression in the primary tumour. In fact, this receptor was expressed in respectively 63% and 38% of primary tumours from patients with and without immunoreactive cells in the bone marrow aspirates. Thus, the presence of immunoreactive cells in bone marrow correlates with the expression in the primary tumour of a marker of the metastatic potential of the tumour, the 67 kDa laminin receptor.

Age Factors↗
PubMed1994

Prognosis based on primary breast carcinoma instead of pathological nodal status.

In breast cancer patients, prognostic information required to plan post-surgical therapy is obtained mainly through axillary dissection. This study was designed to establish a new prognostic score based solely on parameters of the primary tumour as an alternative to axillary surgery in assessing prognosis. Eight different prognostic factors, including menopausal status, tumour size, grading, lymphatic invasion, desmoplasia, necrosis, c-erbB-2 and laminin receptor expression, were evaluated retrospectively on a large series of primary breast carcinoma patients. From multivariate analysis, four independent parameters were selected and examined, alone and in combination, for their prognostic potential. These parameters were used to generate a prognostic score that was analysed retrospectively in 467 N0-N1a patients to determine its predictive value for survival. The score, which includes variables such as tumour size, grading, laminin receptor and c-erbB-2 overexpression, was established based on the number of negative prognostic factors: score 1 refers to cases in which all four parameters reflect a good prognosis, scores 2 and 3 refer to tumours in which, respectively, one or two of the four parameters reflect a poor prognosis, whereas score 4 refers to tumours with three or four poor prognosis factors. Analysis of the overall survival of the four score groups shows that patients with score 1 tumours (22% of the total) had the best prognosis with a 15 year survival of 82%, patients with score 2 and 3 had an intermediate prognosis, whereas score 4 patients had the poorest prognosis with a 15 year survival of only 38%. Moreover, survival in the N+ score 1 cases was found to be longer than that in the total N- patients. Our data suggest that the primary tumour score provides more reliable prognostic information than pathological nodal status, and that axillary dissection can be avoided in a large number of patients.

Breast Neoplasms↗
PubMed1994

Immunoconjugates: lessons from animal models.

Monoclonal antibody-mediated cancer therapy has evolved through a challenging chain of problems and solutions. The very limited therapeutic success obtained with unarmed monoclonal antibodies has increased the interest in different antibody-based targeting strategies, and numerous preclinical and even clinical studies with immunoconjugates have now been conducted. We comment here on the messages implicit in a recent report on a doxorubicin-anti-carcinoma antibody conjugate and from several other studies.

Animals↗
PubMed1994

Protection against doxorubicin-induced alopecia in rats by liposome-entrapped monoclonal antibodies.

Alopecia is a common side effect of several anti-cancer drugs, including doxorubicin. Based on our recent observation that a monoclonal antibody (MAD11) directed against this anthracycline inhibits the systemic toxic effect of the drug in mice, we investigated the possibility that MAD11 administered topically might protect against doxorubicin-induced alopecia. In 31 of 45 young rats treated intraperitoneally with doxorubicin, alopecia was completely prevented by topical treatment of the skin with liposome-incorporated anti-doxorubicin monoclonal antibody. This type of treatment might find relevance in preventing anthracycline-induced alopecia in cancer patients. Our findings also provide the first demonstration that liposome-entrapped monoclonal antibodies are capable of penetrating the stratum corneum of the skin without losing their function.

Alopecia↗