Figure 4

(a) The ovarian cancer cell line ADRr was treated with paclitaxel at increasing doses either alone (gray line), in the presence of 5 nmol/l HRG (red line) or in the presence of 5 nmol/l HRG and 1 μmol/l seribantumab (blue line). The graph illustrates the relative cell viability (normalized to media control) in a 96 h spheroid formation assay with CellTiter Glo as readout of viability. The arrows highlight the effect of HRG or HRG in combination with seribantumab on the response to paclitaxel. (b) A panel of ovarian cancer cell lines was screened using the same assay as in (a). The Area Under the Curve (AUC) fold-change relative to media control of all ovarian cancer cell lines screened, was plotted for paclitaxel in the absence or presence of HRG. Diamond shapes indicate cell lines that are non-responsive to HRG and the larger circles represent the HRG-responding cell lines. The gray region in the plot represents the area where HRG desensitizes cells to paclitaxel. (c) The AUCs of all HRG-responding cell lines screened was calculated for paclitaxel in the presence of HRG, with or without 1 μmol/l seribantumab. The yellow and gray represent the areas in which seribantumab sensitized versus desensitized cells to the drug, respectively. (d) Seribantumab inhibits both basal and HRG-induced p-ErbB3 and p-Akt in A2780cis. Serum-starved A2780 and A2780cis were pre-treated with seribantumab (1 μmol/l) for 24 h, followed by treatment with 10 nmol/l HRG for 10 min. A2780cis cells displays upregulation of basal p-ErbB3 and p-Akt compared with parental A2780 cell line. In vivo activity of seribantumab in A2780 (e) and A2780cis (f) ovarian cancer xenografts. Tumors were established subcutaneously (s.c.) in nu/nu mice. Following randomization, animals were treated with vehicle control (PBS), seribantumab (600 μg/dose, q3d, intraperitoneal (i.p.)), paclitaxel (40 mg/kg, q7d, i.p.) or combination of both drugs (n=8/group). Tumor volumes were calculated following caliper measurement and plotted as mean±s.e.m.