A bispecific antibody-drug conjugate (bsADC), BCG017-vcMMAE, targeting both PTK7 and EGFR demonstrated potent anti-tumor activity in various cancer models. This bsADC showed high binding and internalization in vitro, suggesting improved tumor selectivity. Surprisingly, BCG017-vcMMAE exhibited enhanced efficacy compared to benchmarks and parental ADCs in patient-derived xenograft (PDX) models with low PTK7 expression, indicating potential benefits in heterogeneous tumors expressing both PTK7 and EGFR. Further development with topoisomerase I inhibitors (TOP1i) conjugates is ongoing.