DuoBody-CD3xB7H4 demonstrated antitumor activity in ovarian and breast cancer PDX models with high B7H4 expression. Antitumor activity of DuoBody-CD3xB7H4 in an ovarian cancer PDX model was confirmed in a dose-response study...High prevalence of B7H4 expression was observed in primary NSCLC-SCC, ovarian, endometrial, and breast cancer tissue. In vitro, DuoBody-CD3xB7H4 showed antitumor activity across a range of B7H4 expression levels.