PTK7 and TROP2 are two tumor-associated antigens (TAAs) highly expressed in TNBC and other solid tumors. The PTK7 x TROP2 bsAbs showed enhanced internalization in vitro compared with parental monovalent antibodies. BCG033-vcMMAE bsADCs, simultaneously targeting both PTK7 and TROP2, showed superior efficacy compared to benchmark and parental single-targeting ADCs in PDX models with varying levels of PTK7 expression and in non-TNBC breast cancer xenografts. BCG033-BLD1102 bsADCs showed potent anti-tumor activity in a colon cancer PDX model, whereas the benchmark ADCs failed to elicit a response. Further preclinical studies for BCG033-BLD1102 are ongoing.