Efficacy and Concentration-Response of Murine Anti-VEGF Monoclonal Antibody in Tumor-Bearing Mice and Extrapolation to Humans

Abstract

The development of a neovascular supply (angiogenesis) is a major aspect of tumorigenesis. Recent work has indicated that vascular endothelial growth factor (VEGF) is a major regulator of angiogenesis. In vitro and in vivo studies have demonstrated that an anti-VEGF antibody is capable of suppressing the growth of human tumor cell lines. The following study was conducted in tumor-bearing nude mice to evaluate the concentration-response relationship of murine anti-VEGF monoclonal antibody (muMAb VEGF) so that an efficacious plasma concentration of the recombinant humanized form (rhuMAb VEGF) in cancer patients could be estimated. (This study was included in our Investigational New Drug application to support the clinical dosing regimen and projected human safety factors for the toxicology program.) Additionally, the growth dynamics of the tumors were evaluated as a function of dose to explore whether a mechanismic interpretation of tumor growth inhibition by muMAb VEGF is possible. On day 1, A673 human rhabdomyosarcoma cells (2 x 10(6) cells/mouse) were injected subcutaneously in 188 beige nude mice (16-24 g). Treatment with muMAb VEGF (0.05-5.0 mg/kg; n = 24/group), phosphate-buffered saline (n = 10), or anti-gp120 isotype-matched control antibody (5.0 mg/kg; n = 10) began 24 hr later. Each animal received intraperitoneal injections of test material twice weekly for 4 wk. Immediately prior to each dose, 2 mice from each muMAb VEGF group were selected randomly, and plasma was collected for pharmacokinetic evaluation; at the end of the study, samples were collected from all animals for pharmacokinetic evaluation. Tumor dimensions were recorded weekly, and at the end of the study, tumor weight and dimensions were recorded. Satisfactory tumor suppression in nude mice was achieved at muMAb VEGF doses of > or =2.5 mg/kg, where the average trough muMAb VEGF plasma concentration was 30 microg/ml (concentrations in individual animals >10 microg/ml). Assuming the pharmacokinetics of rhuMAb VEGF in patients will resemble the pharmacokinetics of a similar humanized anticancer monoclonal antibodies, a clinical dosing regimen was designed to maintain the rhuMAb VEGF plasma concentration in this efficacious range. This study shows an approach that can be used to estimate a human dosing regimen from preclinical pharmacokinetic/pharmacodynamic data. Because we have just initiated clinical trials with rhuMAb VEGF we cannot judge clinical outcome in relation to these preclinical predictions; nonetheless, it is hoped that by sharing our approach and thought processes with other investigators we can assist the discovery and development of anticancer therapeutics.

Inhibition of K562 leukemia angiogenesis and growth by expression of antisense vascular endothelial growth factor (VEGF) sequence

“…Recognition of the important role of VEGF resulting from autocrine and/or paracrine regulation in hematologic malignancies has raised expectations for VEGF as an emerging target for antileukemia intervention. The corresponding strategies include decreasing the production of VEGF (antisense strategy), 22 blocking the binding of VEGF to its receptors (monoclonal anti-VEGF or soluble receptor), 23,24 and inhibiting VEGF receptor tyrosine kinases. 25,26 Several investigators have suggested the use of vectormediated gene therapy of antisense sequence in tumor models.…”

Inhibition of renal cell carcinoma angiogenesis and growth by antisense oligonucleotides targeting vascular endothelial growth factor

“…Its expression level has been associated with a variety of tumours and correlated to treatment outcome (Maeda et al, 1996;Gasparini et al, 1997). To date, attempts to abrogate the angiogenic activity of VEGF have focused on inactivating VEGF through the use of antibodies (Kim et al, 1993;Mordenti et al, 1999) and soluble receptors (Lin et al, 1998), inhibiting VEGF receptor tyrosine kinases (Hennequin et al, 1999) or suppressing VEGF message (Ellis et al, 1996;Smyth et al, 1997;Nguyen et al, 1998). The latter relied on antisense oligonucleotides or antisense RNA (Eguchi et al, 1991;Mercola and Cohen, 1995;Phillips and Zhang, 2000) to modulate gene expression by disrupting RNA expression.…”

Cationic lipid-based delivery system for systemic cancer gene therapy

“…25 There are several alternative types of genes that can be expressed with increased potency. These can be other antiangiogenic factors, such as angiostatin, 26 endostatin, 27 proteolyzed antithrombin 3, 28 pigment epithelium-derived factor, 29 soluble Flk1, 30 or humanized Abs raised against growth factor receptors, such as epidermal growth factor receptor, 31 vascular endothelial growth factor, 32 or vascular endothelial growth factor receptor. 33 These genes can be administered by themselves or in combination and can be expressed on the same plasmid.…”