Tumour targeting of humanised cross-linked divalent-Fab' antibody fragments: a clinical phase I/II study.
Bottom Line: A humanised divalent-Fab' cross-linked with a bis-maleimide linker referred to as humanised divalent-Fab' maleimide was produced as a result of this design process.It is a humanised divalent antibody with no Fc, which can be produced in bacteria and has enhanced stability compared with F(ab')(2).However the reduction in immunogenicity was also a major advantage for A5B7 humanised divalent-Fab' maleimide over murine versions of this antibody suggesting that humanised divalent-Fab' maleimide should be a useful vehicle for repeated therapies.
Affiliation: Cancer Research UK Targeting and Imaging Group, Department of Oncology, Royal Free and University College Medical School, University College London, Royal Free Campus, Rowland Hill Street, London NW3 2PF, UK.Show MeSH
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Mentions: An aliquot of hDFM was test labelled with 185 MBq131I, with >90% incorporation. TLC analysis after desalting confirmed that 98.8% of radiolabel was attached to hDFM. Antigen binding post labelling, measured by applying a sample to a 1 ml CEA column, produced 98% retention of antigen binding post labelling. This was confirmed by performing an ELISA with samples pre and post labelling. Gel filtration analysis after radiolabelling showed the presence of a single peak of molecular weight 100 kDa, with no evidence of aggregation or breakdown. A sample of 131I-hDFM was incubated in normal human serum for 24 h (approximately) and analysed by gel filtration. The trace showed a single peak consistent with hDFM. Radiolabelled hDFM in nude mice bearing human colorectal tumour xenografts showed good tumour uptake and retention, with no uncharacteristic binding to other normal organs (Figure 1Figure 1
Affiliation: Cancer Research UK Targeting and Imaging Group, Department of Oncology, Royal Free and University College Medical School, University College London, Royal Free Campus, Rowland Hill Street, London NW3 2PF, UK.