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Query: UNIPROT:P04626 (erbB-2)
 5,251 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bispecific murine monoclonal antibody 2B1, possessing dual specificity for the human c-erbB-2 protooncogene product and human Fc gamma receptor III (CD16) was evaluated for the ability to promote specific lysis of c-erbB-2-positive tumor cells in vitro. In short-term 51Cr release assays with human mononuclear cells as effectors and SK-Br-3 human breast cancer cells as targets, neither parental antibody of 2B1 mediated significant specific lysis, but bispecific antibody was as active as a chemical heteroconjugate, with 5 ng/ml of 2B1 causing half-maximal lysis at an effector/target ratio of 20:1 and 2 ng/ml 2B1 causing half-maximal lysis at an E/T ratio of 40:1. The cytotoxic targeting activity of 2B1 F(ab')2 fragment was the same as that of whole bispecific antibody, and the activity of whole 2B1 was not reduced when assays were performed in 100% autologous human serum, indicating that 2B1 binds effector cells through the CD16-binding site derived from parental antibody 3G8 rather than through its Fc portion. Variable inhibition of 2B1-mediated lysis was observed when autologous polymorphonuclear leukocytes from different donors were added to mononuclear effector cells at a 2:1 ratio; this inhibition was overcome at higher antibody concentration. 2B1 bispecific monoclonal antibody was also able to mediate targeted cytolysis using whole human blood as a source of effector cells or using effector or target cells derived from ovarian cancer patients.
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PMID:In vitro cytotoxic targeting by human mononuclear cells and bispecific antibody 2B1, recognizing c-erbB-2 protooncogene product and Fc gamma receptor III. 136 Aug 72

New strategies are required to clinically exploit the ability of monoclonal antibodies to target tumor for lysis by cellular effector mechanisms. In this report we examine the therapeutic effects of 2B1, a bispecific monoclonal antibody with specificity for the extracellular domain of the c-erbB-2 oncogene product and the human Fc gamma receptor, Fc gamma RIII (CD16), describe the characteristics and limitations of this model, and examine the mechanisms underlying the observed responses. The model uses SK-OV-3 human ovarian carcinoma xenografts in scid mice. These cells are susceptible to 2B1-directed lysis by human peripheral blood lymphocytes or lymphokine-activated killer cells, and maintain c-erbB-2 expression in vivo. 125I-labeled 2B1 selectively accumulates in tumor, with a peak of 10.5% injected dose/g of tumor 24 h following its i.v. injection. However, the selectivity of this binding is lessened by 2B1 accumulation in the lungs and other normal organs and persistence in the blood. This is caused by antibody binding to murine lung, colon, stomach, and skin expressing the epitope recognized by the anti-c-erbB-2 component of 2B1 in tumor-bearing, but not normal mice. In treatment studies using various permutations of antibody, human peripheral blood lymphocytes or lymphokine-activated killer cells and interleukin 2, cellular therapy alone had minimal effects on SK-OV-3 xenograft growth, but significantly improved when 2B1 treatment was incorporated. Median survivals increased from 80 +/- 3.5 days with no therapy to 131 +/- 7.3 days following therapy with 100 micrograms 2B1, interleukin 2, and human peripheral blood lymphocytes, with 70% of animals exhibiting no evidence of tumor at day 150. These effects were preserved when the cells were administered in human serum. In contrast, human serum abolished the antitumor effects of 520C9, which is the parent anti-c-erbB-2 antibody of 2B1. Thus 2B1-based therapy has therapeutic effects, without obvious toxicity, despite the targeting of this antibody to normal murine tissues. Since combinations of 2B1 and interleukin 2 may have antitumor properties, mechanisms other than bispecific monoclonal antibody-promoted conjugation of c-erbB-2 antigen-expressing tumor to CD16-expressing effector cells may be involved.
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PMID:A human tumor xenograft model of therapy with a bispecific monoclonal antibody targeting c-erbB-2 and CD16. 809 31

Bispecific monoclonal antibodies (BsmAb) with specificity for tumor Ag and effector cell trigger molecules have been shown to redirect the cytotoxicity of several peripheral blood mononuclear cell populations against relevant tumor. The BsmAb, 2B1, binds to the extracellular domain of the c-erbB-2 gene product of the HER2/neu proto-oncogene and to CD16. In this report, the binding and cytotoxic characteristics of 2B1 are presented. Maximal saturation binding of 2B1 to PBL and c-erbB-2 expressing SK-OV-3 cells occurred in the 1 microgram/ml concentration range. However, substantial lysis potentiation was observed at 1000-fold lower BsmAb concentrations. Optimal tumor lysis was obtained when the BsmAb, PBL, and target cells were continuously coincubated. When PBL were franked with 2B1, washed, and added to labeled targets, substantially less lysis was observed. These results suggest that the best way to therapeutically exploit the cytotoxic attributes of 2B1 may be to obtain continuous BsmAb exposure to tumor. Approaches based on franking of this BsmAb to PBL may not be warranted.
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PMID:Binding and cytotoxicity characteristics of the bispecific murine monoclonal antibody 2B1. 810 70

2B1 is a bispecific murine monoclonal antibody (bsmAb) targeting the c-erbB-2 and CD16 (Fc gamma RIII) antigens. c-erbB-2 is over-expressed by a variety of adenocarcinomas, and CD16, the low-affinity Fc gamma receptor for aggregated immunoglobulins, is expressed by polymorphonuclear leukocytes (PMN), natural killer (NK) cells and differentiated mononuclear phagocytes. 2B1 potentiates the in vitro lysis of c-erb-2 over-expressing tumors by NK cells and macrophages. In this report, the interactions between 2B1 and PMN were investigated to assess the impact of these associations on in vitro 2B1-promoted tumor cytotoxicity by human NK cells. The peak binding of 2B1 to PMN was observed at a concentration of 10 microgram/ml 2B1. However, 2B1 rapidly dissociated from PMN in vitro at 37 degrees C in non-equilibrium conditions. This dissociation was not caused by CD16 shedding. When PMN were labeled witn 125I-2B1 and incubated at 37 degrees C and the supernatants examined by HPLC analysis, the Fab regions of dissociated 2B1 were not complexed with shed CD16 extracellular domain. While most of the binding of 2B1 PMN was solely attributable to Fab-directed binding to Fc gamma RIII, PMN-associated 2B1 also bound through Fc gamma-domain/Fc gamma RII interactions. 2B1 did not promote in vitro PMN cytotoxicity against c-erbB-2-expressing SK-OV-3 tumor cells. When PMN were coincubated with peripheral blood lymphocytes, SK-OV-3 tumor and 2B1, the concentration of 2B1 required for maximal tumor lysis was lowered. Although PMN may serve as a significant competitive binding pool of systemically administered 2B1 in vivo, the therapeutic potential of the targeted cytotoxicity properties of this bsmAb should not be compromised.
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PMID:Human neutrophil interactions of a bispecific monoclonal antibody targeting tumor and human Fc gamma RIII. 864 Aug 42

Twenty percent of breast cancer adenocarcinomas overexpress the oncogene c-erb-2 that is recognized by the humanized anti-Her2/neu monoclonal antibody Herceptin. Results from clinical studies suggest that antibody-dependent cellular cytotoxicity (ADCC) is involved in the clinical response of Herceptin-treated patients. The purpose of the current study was to evaluate the possibility of amplifying in vitro the CD3-/CD16+ natural killer (NK) cell subset that mediates ADCC from breast cancer patients after chemotherapy. Peripheral blood mononuclear cells from six breast cancer patients taken 2 months after chemotherapy completion were co-cultured with an autologous irradiated Epstein-Barr virus-transformed B-lymphoblastoid cell line (LCL) in the presence of interleukin-2 (IL-2) for 4-6 weeks. These LCL + IL2 activated cultures (ACs) were tested for ADCC potential, and their CD3/CD16 NK proportion was quantified. Among the ACs, the proportion of CD3-/CD16+ NK cells increased up to 64% over the first 2 weeks of culture and the ACs continued to expand for 1 month thereafter. Control and patient ACs displayed ADCC activity (tested in the presence of Rituximab against the autologous LCL to take into account any possible effect of inhibitory NK receptors) as well as against the MCF-7(Her2/neu) breast cancer cell line in the presence of Herceptin. This ADCC activity was maintained during the entire culture period. In conclusion, chemotherapy in breast cancer patients does not obviate the possibility of amplifying in vitro the NK cell subset that mediates ADCC. Consequently, adoptive transfer of lymphocytes mediating ADCC can be considered using this protocol to test its benefit in patients under Herceptin treatment.
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PMID:Long-term preservation of antibody-dependent cellular cytotoxicity (ADCC) of natural killer cells amplified in vitro from the peripheral blood of breast cancer patients after chemotherapy. 1636