Isolation and characterization of an inhibitory human monoclonal antibody specific to the urokinase-type plasminogen activator, uPA

The serine protease urokinase (uPA, urokinase-type plasminogen activator) is over-expressed in certain tumors and is considered to be the strongest single indicator of poor prognosis in patients with metastatic breast cancer. In this article, we describe the isolation and affinity maturation of a fully human recombinant antibody (termed DS2), specific to the human uPA and capable of inhibiting its enzymatic activity with an IC50 value in the low nanomolar range. The novel antibody cross-reacts with murine uPA. It was expressed both as scFv fragment and in IgG format, allowing a systematic comparative immunofluorescence (IF) analysis of the uPA expression patterns in a large panel of human und murine tumors and of normal human tissues. Although uPA was strongly expressed in virtually all tumor specimens tested, it exhibited only a weak expression in certain normal tissues (mainly in the colon, lung, spleen and bone marrow). IgG(DS2) was not able to inhibit cancer growth in immunocompromised mice bearing subcutaneous human MDA-MB-231 or DoHH-2 tumors. However, an ex vivo IF analysis confirmed the ability of the DS2 antibody to preferentially localize at the tumor site compared with normal organs. Collectively, these data suggest that uPA blocking antibodies may not be indicated for cancer growth inhibition strategies, but may serve as valuable tools for the implementation of pharmacodelivery strategies against a variety of different tumor

Tumour-targeting properties of antibodies specific to MMP-1A, MMP-2 and MMP-3

Purpose: Matrix metalloproteinases (MMPs), a group of more than 20 zinc-containing endopeptidases, are upregulated in many diseases, but several attempts to use radiolabelled MMP inhibitors for imaging tumours have proved unsuccessful in mouse models, possibly due to the limited specificity of these agents or their unfavourable pharmacokinetic profiles. In principle, radiolabelled monoclonal antibodies could be considered for the selective targeting and imaging of individual MMPs. Methods: We cloned, produced and characterized high-affinity monoclonal antibodies specific to murine MMP-1A, MMP-2 and MMP-3 in SIP (small immunoprotein) miniantibody format using biochemical and immunochemical methods. We also performed comparative biodistribution analysis of their tumour-targeting properties at three time points (3h, 24h, 48h) in mice bearing subcutaneous F9 tumours using radioiodinated protein preparations. The clinical stage L19 antibody, specific to the alternatively spliced EDB domain of fibronectin, was used as reference tumour-targeting agent for in vivo studies. Results: All anti-MMP antibodies and SIP(L19) strongly stained sections of F9 tumours when assessed by immunofluorescence methods. In biodistribution experiments, SIP(SP3), specific to MMP-3, selectively accumulated at the tumour site 24 and 48h after intravenous injection, but was rapidly cleared from other organs. By contrast, SIP(SP1) and SIP(SP2), specific to MMP-1A and MMP-2, showed no preferential accumulation at the tumour site. Conclusion: Antibodies specific to MMP-3 may serve as vehicles for the efficient and selective delivery of imaging agents or therapeutic molecules to sites of diseas

Isolation and characterization of an inhibitory human monoclonal antibody specific to the urokinase-type plasminogen activator, uPA

ISSN:1741-0126ISSN:1741-0134ISSN:0269-2139ISSN:1460-213

Tumour-targeting properties of antibodies specific to MMP-1A, MMP-2 and MMP-3

ISSN:1619-7070ISSN:1619-708