Fig. 6.

Both in vitro and in animals, combinations of noncompetitive mAbs to HER3 only weakly enhance the inhibitory effects of the respective single Abs. (A–C) Proliferation assays using MTT were performed on BXPC3 cells (5,000 cells per well). Cells were plated on the day before and treated for 72 h with the indicated mAbs. Increasing concentrations of the indicated mAbs (either alone or in combination) were used in medium supplemented with 1% serum and NRG (10 ng/mL). An irrelevant IgG fraction was used as control. (D–F) CD1-nude mice were grafted s.c. with 5 × 10⁶ BXPC3 cells. Once tumors became palpable (after 13 d), the mice were randomized into groups of eight animals and treated once every 3 d for 5 wk. The control group (CTRL) was injected intraperitoneally (IP) with 200 µL of PBS. The other groups were treated with the indicated mAbs, either alone or in combinations, at a final concentration of 0.2 mg/0.2 mL saline per mouse. Body weight was determined once a week, and the tumors were measured twice a week. Shown are average tumor sizes from seven or eight mice (±SEM).