A single chain Fv derived from a filamentous phage library has distinct tumour targeting advantages over one derived from a hybridoma

Abstract

Single-chain antibodies (scFvs) can be derived from a monoclonal antibody (MAb) or produced directly using filamentous phage technology, where antibodies with desired binding and purification characteristics can be readily selected from libraries. To test the hypothesis that the latter approach is more useful, we compared 2 anti-carcinoembryonic antigen (CEA) scFvs produced by these 2 different approaches. Our study showed that, both in the purification process and in the biodistribution pattern, MFE-23, produced by filamentous phage technology, gave favourable results compared to A5-SC, which is derived from the A5B7 MAb. This indicates the value of the filamentous phage approach for obtaining tumour-targeting scFvs.

Recombinant adenoviral delivery for in vivo expression of scFv antibody fusion proteins

“…5 Indeed, such fragments made from phage libraries 6 appear superior to those derived from pre-existing monoclonal antibodies in tumour targeting models. 7 Recently their activity in patient imaging studies has been established and this work also confirms the short half-life of such fragments in the human circulation. 8 Fusion proteins with such scFv fragments are attractive for therapeutic use but the short half-life means that continuous infusion for a period of time may be required to obtain sufficient target tissue concentrations and that large quantities will need to be administered.…”

Tumor‐targeting properties of antibody–vascular endothelial growth factor fusion proteins

“…injection, whereas tumor:tissue ratios ranged between 0.5 and 3 for blood, liver, kidney, lung and spleen. These results are significantly less impressive than the results obtained by the same group with an scFv fragment specific for carcinoembryonic antigen [scFv(MFE-23)], 55 an agent that has moved into clinical development. 56,57 Cutting-edge genomic research has devoted a great deal of attention to the search for markers specifically expressed in the luminal aspect of tumor endothelium, but not in normal endothelial cells, 58,59 for use as targets for biomolecular intervention.…”

Antigen specificity and tumour targeting efficiency of a human carcinoembryonic antigen-specific scFv and affinity-matured derivatives

“…In nude mice it produces moderately differentiated CEA-producing adenocarcinomas that secrete no measurable CEA into the circulation (Pedley et al, 1993). Tumour localization of both murine and chimaeric CEAspecific antibodies, antibody fragments and scFv has been demonstrated using this tumour xenograft model (Harwood et al, 1985;King et al, 1994;Verhaar et al, 1995;Hu et al, 1996). The biodistribution and tumour localization of ['251]scFv were examined in female MFI nulnu mice (weighing 20-25 g) bearing heterotransplanted LS 174T tumours (at a mean size of 650 mg; range 500-800 mg).…”

“…Control scFv were as follows: a human scFv FITC-E2, specific for the hapten fluorescein (Vaughan et al, 1996) was Table 1 Affinity-matured scFv derivatives of CEA6 scFv Origin included as a negative control, while a murine CEA-specific scFv, MFE23, kindly provided by Dr K Chester, Royal Free Hospital, London, UK, was used as a positive control. MFE23 has previously been shown to localize to CEA-expressing tumours in mice and to metastatic liver deposits of colorectal tumours in humans (Chester et al, 1994;Verhaar et al, 1995;Begent et al, 1996). lodination was carried out using a modification of the lodoGen method (Pimm and Gribben, 1993).…”

“…Poor tumour penetrance of whole immunoglobulin has been addressed through the use of smaller fragments derived both enzymatically and by recombinant methods (Yokota et al, 1992;Hu et al, 1996;Rowlinson-Busza et al, 1996). Further advantages of fragments are their rapid extravasation and pharmacokinetic clearance, which are clearly contributing factors in their improved performance as imaging agents (Colcher et al, 1990;Milenic et al, 1991;Verhaar et al, 1995). Moreover, the immunogenicity of rodent monoclonal antibodies (mAbs) has been reduced either by humanization strategies or by de novo isolation of antibody fragments from combinatorial libraries of human V genes (reviewed by Johnson and Chiswell, 1993).…”