Comparative analysis of binding affinities to epidermal growth factor receptor of monoclonal antibodies nimotuzumab and cetuximab using different experimental animal models.

Although pharmaco/toxicological studies have always been conducted in pharmacologically relevant species in which the test material is pharmacologically active, the very specificity of many biopharmaceuticals could present challenges in the identification of a relevant species for pharmaco/toxicological studies. Alternative approaches may improve the predictive value of preclinical assessments of species-specific biopharmaceuticals. This could lead to improved decision-making, reduce the number of experimental animals by eliminating non-relevant studies, and decrease the time and cost involved in the drug development process. As an alternative to utilizing traditional animal models, this study investigated the activity of human EGF and the anti-EGF receptor monoclonal antibodies nimotuzumab and cetuximab using the placenta microsomal fraction of different experimental animals. Ligand-receptor binding curves were obtained from the different experimental animal models, and binding constants were calculated based on the Scatchard plots. The constants for human and monkey EGF receptor expressed on the placental extract showed a K(a)<10(-8)M, while rabbits, mice and rats showed a K(a)>10(-8)M. The K(a) values obtained from animal placentas show that Macaca fascicularis and Cercopitecus aethiops monkeys are relevant species for studying the pharmaco/toxicological properties of nimotuzumab and cetuximab.

Kinetics of monoclonal anti-epidermal growth factor receptor antibody (IOR EGF/r3)-induced apoptosis in human carcinoma bearing nude mice

Apoptosis seems to play an important role in cancer immunotherapy outcome. We have studied the kinetic pattern of apoptosis induction in H125 human lung carcinoma xenografts after treatment with the monoclonal antibody (MAb) anti-epidermal growth factor receptor (EGFr) IOR EGF/r3. Tumor-bearing nude mice were injected intravenously with a single 8 mg/kg dose of IOR EGF/r3 and tumor specimens were taken up to 30 days post treatment. Apoptosis was measured by morphometric analysis of the histological sections at each tumor specimen over time points. The results showed a significant apoptotic response in tumors within six days after injection of this MAb reaching a peak at 20 days post treatment. The kinetics were very broad, with apoptotic cells present over the entire time-frame. However, the time course of the apoptotic index showed a significant difference to the mitotic index. Finally, the MAb-induced apoptosis was related to tumor growth delay indicating a probable arrest of cell cycle and a corresponding inhibition of tumor progression, which was corroborated by the Ki67 and proliferating cell nuclear antigen (PCNA) biomarkers.

Monoclonal anti-EGFreceptor antibody (ior-R3) pharmacokinetic study in tumor bearing nude mice: role of the receptor-mediated endocytosis on drug clearance.

With the purpose of describing the MAb ior-R3's kinetic behavior in disease state, this paper is focused on the study of this response using a human cancer (lung carcinoma cell line, H125) bearing nude mice animal model. This MAb was administered by a single 16 mg/Kg intravenous bolus dose and the blood samples were collected at several times ranging from 0 to 72 hours for serum drug quantification. The experimental data set was best fitted using a classical two-compartment mammilary pharmacokinetic (PK) model and the corresponding PK parameters were determined. Comparatively, the analysis of the more relevant physiologically-based PK parameters showed a significant enhancing of clearance as compound with the earlier reported study on healthy mice, increasing from 0.09 to 0.19 mL/h (p<0.01). However, the corresponding distribution volumes don't seem to be altered by the tumor xenograft. We conclude that all of these evidences suggest a possible mechanism of receptor-mediated endocytosis (RME) as a major cause of this increased drug clearance which also contributed to the faster decrease of the drug disposition.

Monoclonal anti-epidermal growth factor receptor (ior EGF/r3) antibody pharmacokinetic studies on nude mice I: a radio-receptor analysis applied to drug serum quantification.

Due to its antagonistic properties upon ligand-epidermal growth factor receptor (EGFr) interaction, the monoclonal antibody anti-EGFr ior EGF/r3 is considered a potential therapeutic agent against several epithelium-derived tumours. This paper affords further analysis of the relevant corporal interaction of this monoclonal antibody in terms of its pharmacodynamic properties, using nude mice, following a single bolus intravenous dose administration. The radio-receptor assay allows quantification of the serum ior EGF/r3 level. The dose selection procedure, according to the Kolmogorov-Smirnov test, suggested using doses of 12.5-16 mg kg(-1) for pharmacokinetic assessments. The experimental data were best fitted to a bi-exponential function (r2 = 0.985), through the classical two-compartment open modelling approach. The model selection was corroborated by the AKAIKE information criteria, and also the SCHWARTZ and ESTRIP test were used. The estimated pharmacokinetic parameters (e.g. t 1/2 beta = 34.65 h, Vc = 2.84 mL, Vss = 4.21 mL and CL = 0.09 mL h(-1)) bear out the strategies for the evaluation of the therapeutic application of this drug. Finally, the radio-receptor analysis has provided a rationale for the proposed serum monoclonal antibody ior EGF/r3 quantification to characterize its concentration-time course.

Antitumor properties of an anti-idiotypic monoclonal antibody in relation to N-glycolyl-containing gangliosides.

We examined the antitumor effects of 1E10 monoclonal antibody, an anti-idiotypic IgG to an IgM monoclonal antibody, named P3, that reacts specifically with N-glycolyl-containing gangliosides and also recognizes antigens in human breast and melanoma tumors. Two murine tumor cell lines positive for the P3 antibody, F3II mammary carcinoma (BALB/c) and B16 melanoma (C57BL/6), were employed. In BALB/c mice, vaccination with several i.p. doses at 14-day intervals of 50 microgram of 1E10 coupled to keyhole limpet hemocyanin in Freund's adjuvant, significantly reduced s.c. tumor growth of F3II carcinoma cells and the number of spontaneous lung metastases. Also, the effect of 1E10 as a biological response modifier on tumor lung colonization was evaluated in C57BL/6 mice injected i.v. with B16 melanoma cells. Interestingly, i.v. administration of 10 microgram of uncoupled 1E10 antibody, 10-14 days after inoculation of B16 cells, dramatically reduced the number of experimental metastases in comparison with lungs from mice treated with an irrelevant IgG. The present data suggest that this 'non-internal image' anti-idiotypic monoclonal antibody may activate more than one mechanism of antitumor response against melanoma and mammary tumor cells.