Figure 5

Dual Targeting of EGFR and ErbB3: (a) Mechanistic model to predict the response of seribantumab and erlotinib combination in A549, ACHN, DU145 and H322M cells. The initial conditions for the four cell lines (e.g., receptor levels) were set to those measured by qFACS under basal conditions (Supplementary Table S3).For each cell line the simulation was run for 30 min to allow the receptors to equilibrate. The inhibitors were then introduced for an additional 30 min, followed by virtual stimulation with HRG (1 nmol/l) and BTC (1 nmol/l) for 10 min to assess the effect of the inhibitors on Akt phosphorylation. Values are normalized to cells treated with HRG and BTC alone. (b) In vitro signal inhibition with the combination of seribantumab and erlotinib in H322M cells. Serum-starved H322M cells were pre-treated with either seribantumab (1 μmol/l), erlotinib (1μmol/l) or the combination for 30 min, followed by treatment with different ligands; HRG (10 nmol/l) alone, EGF (10 nmol/l) alone or both ligands for 1 h. Cell lysates were used for western blot analysis. In vivo activity of seribantumab in A549 (c) and H322M (d) xenografts. Subcutaneous tumors were established in nu/nu mice. Following randomization, animals were treated with vehicle control (PBS), seribantumab (300 μg/dose, q3d, intraperitoneal (i.p.)), erlotinib (25 mg/kg, q3d, oral gavage) or combination of both drugs (n=8/group). Tumor growth was measured twice per week by calipers and plotted as mean±s.e.m. and plotted on a log scale to assess the tumor growth kinetics for each treatment arm. (e) Tumor growth rate inhibition for A549 and the H322M xenograft model for the individual treatment arms and the combination compared with Bliss independence.