Pharmacodynamics of DT-IgG, a dual-targeting antibody against VEGF-EGFR, in tumor xenografted mice.

PURPOSE: DT-IgG is a fully humanized dual-target therapeutic antibody being developed to simultaneously target epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF), important signaling molecules for tumor growth. The antitumor pharmacodynamics (PD) of DT-IgG was studied in nude mice bearing human tumor xenografts with different EGFR and VEGF expressions and K-ras oncogene status and compared with bevacizumab, cetuximab and bevacizumab + cetuximab. METHODS: Mice bearing human oral squamous cell carcinoma (Tu212), lung adenocarcinoma (A549), or colon cancer (GEO) subcutaneous xenografts were administered with the antibodies intraperitoneally (i.p.), and tumor volumes were measured versus time. Nonlinear mixed effects modeling (NONMEM) was used to study drug potencies (IC(50)) and variations in tumor growth. RESULTS: The PD models adequately described tumor responses for the antibody dose regimens. In vivo IC(50) values varied with EGFR and K-ras status. DT-IgG had a similar serum t (1/2) as cetuximab (~1.7 vs. 1.5 day), was more rapid than bevacizumab (~6 day), and had the largest apparent distribution volume (DT-IgG > cetuximab > bevacizumab). The efficacy of DT-IgG was comparable to bevacizumab despite lower serum concentrations, but was less than bevacizumab + cetuximab. CONCLUSIONS: A lower IC(50) of DT-IgG partially compensated for lower serum concentrations than bevacizumab and cetuximab, but may require higher doses for comparable efficacy as the combination. The model adequately predicted variations of tumor response at the DT-IgG doses tested and could be used for targeting specific tumor efficacies for future testing.

A dual-targeting antibody against EGFR-VEGF for lung and head and neck cancer treatment.

An antibody simultaneously targeting epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF), two major tumor growth-driving machineries, may provide a novel effective strategy for optimizing tumor targeting and maximizing potential clinical benefits. Human domain antibodies selected against VEGF and EGFR were formatted into a fully human dual-targeting IgG (DT-IgG) to directly target both antigens in a single molecule. We evaluated the efficacy of DT-IgG in comparison with bevacizumab and cetuximab alone and in combination in the lung cancer cell line A549 (low EGFR expression and KRAS mutant) and the head and neck squamous cell carcinoma (HNSCC) cell line Tu212 (high EGFR expression and KRAS wild type) in vitro and in vivo. DT-IgG suppressed Tu212 and A549 cell growth, inhibited EGFR activation and induced apoptosis as effectively as cetuximab, and neutralized VEGF as effectively as bevacizumab. DT-IgG induced EGFR-dependent VEGF internalization, constituting a novel antiangiogenesis mechanism. In xenograft models with lung and head and neck cancer cell lines, DT-IgG displayed efficacy equivalent to bevacizumab in diminishing tumor growth despite its short serum half-life (36 hr in rats) and both agents may constitute preferable alternatives to cetuximab in KRAS-mutant tumors. Immunofluorescence staining revealed that localization of DT-IgG was similar to that of cetuximab, largely associated with EGFR+tumor cells. Our proof of principle study suggests a DT-IgG against EGFR and VEGF as an alternative therapeutic strategy with potentially enhanced clinical benefit.