Figure 3.

The combination of trastuzumab + pertuzumab + patritumab inhibits cell viability and downstream pAkt in heregulin‐expressing cells. A, SKBR3‐HRG and BT474‐HRG cells were incubated for 120 h with increasing concentrations of trastuzumab and a fixed dose of pertuzumab (50 μg/mL) and patritumab (20 μg/mL); cell viability was then assessed with Cell Counting Kit‐8. Each point represents the mean ± standard error of three independent experiments. B, SKBR3‐HRG and BT474‐HRG cells were incubated for 24 h in RPMI containing 2% FBS, after which cells were treated with or without trastuzumab (20 μg/mL), pertuzumab (20 μg/mL), and patritumab (20 μg/mL) for 1 h. Then, cells were lysed and subjected to immunoblot analysis for pAkt, Akt, pErk, and Erk, with β‐actin serving as a loading control. C, BT474, MDA‐MB‐453, or HCC1419 cells were incubated for 120 h with increasing concentrations of trastuzumab alone, or trastuzumab, pertuzumab (fixed dose; 50 μg/mL), and patritumab (fixed dose; 50 μg/mL) in the presence of recombinant heregulin (20 ng/mL) in the medium. Cell viability was then assessed with Cell Counting Kit‐8. Each point represents the mean ± standard error of three independent experiments