ERBB2 and breast cancer: This was previously observed in high HER2-expressing BT474 human breast cancer xenografts, although the standalone effect of the anti-HER2 BsAb was small (MS: 62 d for no treatment control, 72 d for BsAb only, and >130 d for anti-HER2 225Ac-DOTA-PRIT) 6.