In this study we characterized the impact of IGF-1R and ErbB3 in ovarian cancer growth and therapy resistance and reveal strategies to re-sensitize ovarian cancer cells to clinically relevant chemotherapy using istiratumab, a fully human bispecific tetravalent IGF-1R- and ErbB3-targeting antibody, composed of a monoclonal IgG1 antibody, engineered to contain two single-chain Fv fragments12,13. Here, IGF1R is linked to ovarian cancer.