A necrosis inducer promotes an immunogenic response and destroys ovarian cancers in mouse xenografts and patient ascites organoids

Most ovarian cancer patients present with advanced disease and there are few targeted therapies; consequently, five-year survival for ovarian cancer remains below 50%. We described the anticipatory unfolded protein response (a-UPR) hyperactivator, ErSO, which induced profound and often complete regression of breast cancer in mouse models. Here we explore the effectiveness of ErSO against ovarian cancer. ErSO induced death of human PEO4 and Caov-3 ovarian cancer cells in vitro. In mouse xenografts, injected ErSO induced rapid complete, or near complete, regression of orthotopic metastatic PEO4 tumors and of Caov-3 ovarian tumors. Ovarian cancer patients often develop malignant ascites containing ovarian cancer organoids that drive metastasis. ErSO showed activity against 7/7 fresh patient derived ascites organoids (PDAOs). Low nanomolar ErSO destroyed 2/7 PDAOs. ErSO-mediated cell death in PDAOs occurred through the same a-UPR activation mechanism seen in cell culture. Moreover, ErSO family compound-induced a-UPR activation in ovarian cancer cells triggers necrotic cell death and release of damage associated molecular patterns (DAMPs), which strongly activated human macrophage and induced monocyte migration. These studies suggest ErSO has unusual potential for treatment of advanced ovarian cancer.