Localization of monoclonal antibody G250 and bispecific monoclonal antibody CD3/G250 in human renal‐cell carcinoma xenografts: Relative effects of size and affinity

Abstract

A study was made of the relative effects of size and binding strength of various forms of the monoclonal antibody (MAb) G250, reacting with primary and metastatic human renal-cell carcinoma (RCC), on the localization in human RCC xenografts in nude mice. Preferential tumor localization was demonstrated after injection of 125I-labelled intact IgG, with increasing tumor/non-tumor ratios in time. Approximately 27.4% of the injected dose/gram (%ID/g) was localized in the xenograft 24 hr post-injection. A control MAb did not preferentially localize in xenografts. With F(ab')2 fragments, higher tumor/blood ratios were obtained, although a lower percentage of injected dose per gram was bound to the tumor, 24 and 48 hr post-injection. Using a bispecific MAb CD3/G250 F(ab')2 fragment, which reacts with CD3 on human T lymphocytes and binds monovalently to RCC, an enhanced accumulation in tumor tissue was also observed. The %ID/g tumor obtained with bispecific CD3/G250 F(ab')2 was comparable with %ID/g tumor found with G250 F(ab')2. The 10-fold lower binding affinity to RCC compared with intact IgG or F(ab')2 had only marginal effects on %ID/g tumor. These results show that MAb G250 preferentially localizes to RCC xenografts. Because injection of F(ab')2 fragments resulted in higher tumor/non-tumor ratios, G250 F(ab')2 may therefore be more suitable for diagnostic evaluation of RCC in patients. The tumor uptake is more dependent on size than on affinity. Furthermore, the data obtained with bispecific MAb CD3/G250 F(ab')2 support the hypothesis that this bispecific MAb may be able to target cytotoxic T lymphocytes to RCC in humans to mediate destruction of RCC.

Human monoclonal antibodies targeting carbonic anhydrase IX for the molecular imaging of hypoxic regions in solid tumours

“…Tumour pre-targeting strategies could also be considered, as they have yielded excellent tumour/organ ratios over a range of time points after injection (van Schaijk et al, 2005). By contrast, Fab and F(ab') 2 preparations of the same antibody did not exhibit improved selectivity compared with the IgG format (van Dijk et al, 1991).…”

“…Monoclonal antibodies have also been used to achieve a selective in vivo localisation on cells, which display a high constitutive expression of CA IX (van Dijk et al, 1991;Chrastina et al, 2003aChrastina et al, , 2003bBrouwers et al, 2004;van Schaijk et al, 2005), especially kidney cancer cells, in which mutations in the gene encoding the von Hippel-Lindau tumour suppressor (pVHL) lead to a constitutive HIF-1a activation and, as a consequence, to a strong upregulation of CA IX on all tumour cells (Wykoff et al, 2000;Mazure et al, 2004). This target was also detected as one of the most prominent accessible markers of renal cell carcinoma (RCC) in a chemical proteomic study, based on the ex vivo perfusion of surgically resected human kidneys with cancer using an active ester derivative of biotin, followed by capture of biotinylated proteins and mass spectrometric analysis (Castronovo et al, 2006).…”

Generation of chimeric bispecific G250/anti-CD3 monoclonal antibody, a tool to combat renal cell carcinoma

“…The G250 antigen is an attractive target for antibodymediated therapy, because of its nearly exclusive expression in renal carcinoma cells. Studies with the G250 MAb and the murine bispecific G250/OKT-3 (anti-CD3) MAb have shown preferential localisation of these antibodies to the tumour (Oosterwijk et al, 1993;van Dijk et al, 1991) and antitumour effects in RCC-xenografted nude mice (van Dijk et al, 1994). The G250/anti-CD3 MAb was chimerised to decrease immunogenicity of the bispecific antibody in patients, because studies in patients with murine anti-tumour antibodies and bispecific antibodies are limited by the development of HAMA responses.…”

“…Murine bispecific G250/anti-CD3 antibody has previously been generated and was shown to induce lysis of RCC cell lines by IL-2-activated human CTLs in vitro (Van Dijk et al, 1989). In nude mice F(ab)2 fragments of the murine bispecific G250/anti-CD3 MAb localised well in xenografted RCC (Van Dijk et al, 1991).…”

“…It has been shown that intravenously administered bispecific MOvl8/anti-CD3 (OC/ TR) MAb, recognising both the ovarian carcinomaassociated antigen MOv18 and the CD3 complex, can localise in tumours in patients (Tibben et al, 1993). Targeted T lymphocytes, bearing bispecific antibody bound to their CD3 complex, may accumulate in the tumour, whereas any bispecific MAb binding to tumour cells first (Van Dijk et al, 1991), may subsequently attract circulating T cells.…”