ERBB2 and cancer: Given that the combination treatment of these 2 different anti-HER2 mAbs induced a stronger antitumor effect on HER2-expressing cancers than by treatment with the agents alone in preclinical and clinical settings, we hypothesized that the combination treatment of these 2 anti-HER2 mAbs conjugated with IR700 and followed by NIR light irradiation would also lead to a stronger antitumor effect than with either agent and NIR light irradiation.