A proprietary, antibody fragment composed of a constant (Fc) region that is engineered to bind to the tumor-associated antigen human epidermal growth factor receptor-2 (HER2), with potential antineoplastic activity. HER2-targeted antibody Fc fragment FS102 specifically binds to its HER2 epitope, and causes downregulation of HER2-mediated signaling. This leads to tumor cell apoptosis. HER2, a member of the receptor tyrosine kinase (RTK) epidermal growth factor receptor (EGFR) superfamily, is overexpressed on the cell surface of various solid tumors.