An antibody-drug conjugate (ADC) composed of a monoclonal antibody directed against the tumor-associated antigen (TAA) human epidermal growth factor receptor 2 (EGFR2; HER2; ErbB2) linked to an undisclosed cytotoxic agent, with potential antineoplastic activity. Upon administration of anti-HER2 ADC BL-M07D1, the anti-HER2 monoclonal antibody moiety targets and binds to HER2 expressed on tumor cells. Upon binding and internalization, the cytotoxic agent is released and kills HER2-expressing tumor cells through an as of yet undisclosed mechanism. HER2, a receptor tyrosine kinase that is mutated or overexpressed in many tumor cell types, plays an important role in tumor cell proliferation and tumor vascularization.