The effect of glycoengineering a membrane specific anti-carcinoembryonic antigen (CEA) (this paper uses the original term CEA for the formally designated CEACAM5) antibody (PR1A3) on its ability to enhance killing of colorectal cancer (CRC) cell lines by human immune effector cells was assessed. In vivo efficacy of the antibody was also tested.

METHODS:

The antibody was modified using EBNA cells cotransfected with beta-1,4-N-acetylglucosaminyltransferase III and the humanised hPR1A3 antibody genes.

RESULTS:

The resulting alteration of the Fc segment glycosylation pattern enhances the antibody's binding affinity to the FcgammaRIIIa receptor on human immune effector cells but does not alter the antibody's binding capacity. Antibody-dependent cellular cytotoxicity (ADCC) is inhibited in the presence of anti-FcgammaRIII blocking antibodies. This glycovariant of hPR1A3 enhances ADCC 10-fold relative to the parent unmodified antibody using either unfractionated peripheral blood mononuclear or natural killer (NK) cells and CEA-positive CRC cells as targets. NK cells are far more potent in eliciting ADCC than either freshly isolated monocytes or granulocytes. Flow cytometry and automated fluorescent microscopy have been used to show that both versions of hPR1A3 can induce antibody-dependent cellular phagocytosis (ADCP) by monocyte-derived macrophages. However, the glycovariant antibody did not mediate enhanced ADCP. This may be explained by the relatively low expression of FcgammaRIIIa on cultured macrophages. In vivo studies show the efficacy of glycoengineered humanised IgG1 PR1A3 in significantly improving survival in a CRC metastatic murine model.

CONCLUSION:

The greatly enhanced in vitro ADCC activity of the glycoengineered version of hPR1A3 is likely to be clinically beneficial.

2008-09-01·British journal of cancer1区 · 医学

In vitro and in vivo anticancer efficacy of unconjugated humanised anti-CEA monoclonal antibodies

1区 · 医学

Letter

作者: H J Hansen ; R D Blumenthal ; D M Goldenberg

A review.A polemic in response to Conaghan et al. (Br. J. Cancer 2008, 98, 1217-1225) is given.In their study, Conaghan et al. presented a statement that 'there are so far no unconjugated, or 'naked' antibodies to carcinoembryonic antigen (CEA) being used for treatment of colorectal cancer'.They also demonstrated some promising in vitro activity of a humanized anti-CEA antibody, PR1A3.The authors believed that Conaghan et al.'s statement is incorrect and hence, provided explanation for this.They also offered evidence for the superiority of the combined modality naked anti-CEA monoclonal antibody (MAb) immunotherapy and chemotherapy treatments.

2008-04-01·British journal of cancer1区 · 医学

Targeted killing of colorectal cancer cell lines by a humanised IgG1 monoclonal antibody that binds to membrane-bound carcinoembryonic antigen

1区 · 医学

Article

作者: S Ashraf ; E Tchilian ; P Conaghan ; J Wilding ; W Bodmer ; M Tytherleigh ; N J Mortensen ; D Bicknell

The distribution of carcinoembryonic antigen (CEA) in colorectal cancer (CRC) differs from that in normal colorectal tissue, being found on all borders of the cell membrane and hence enabling access to intravenous antibody, making CEA a good target for antibody-based therapy. The distinctive anti-CEA antibody, PR1A3, binds only membrane-bound CEA. Humanised PR1A3 (hPR1A3) was assessed both in vitro cytotoxicity and binding assays with colorectal cancer cell lines expressing varying levels of CEA. Human peripheral blood mononuclear cells (PBMCs) and purified natural killer (NK) cells were used as effectors. The in vitro assays demonstrated hPR1A3 CEA-specific binding and antibody-dependent and CEA-specific killing of human colorectal cancer cell lines by human PBMCs. The effect increased with increasing concentration of antibody and surface CEA, and was lost by using the parent murine IgG1 PR1A3. Killing was also blocked by antibody to the Fc-gammaIIIA receptor. Purified human NK cells were effective at much lower effector:target ratios than unfractionated PBMCs, indicating that NK cells were the main mediators of hPR1A3-based CEA-specific killing. The results support the development of hPR1A3 for therapy of colorectal cancer.

100 项与 PR1A3 相关的药物交易

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