Drug screening and grouping by sensitivity with a panel of primary cultured cancer spheroids derived from endometrial cancer

Several molecular targeting drugs are being evaluated for endometrial cancer; selecting patients whose cancers are sensitive to these agents is of paramount importance. Previously, we developed the cancer tissue‐originated spheroid method for primary cancer cells taken from patients’ tumors as well as patient‐derived xenografts. In this study, we successfully prepared and cultured cancer tissue‐originated spheroids from endometrial cancers. Characteristics of the original tumors were well retained in cancer tissue‐originated spheroids including morphology and expression of p53 or neuroendocrine markers. We screened 79 molecular targeting drugs using two cancer tissue‐originated spheroid lines derived from endometrioid adenocarcinoma grade 3 and serous adenocarcinoma. Among several hits, we focused on everolimus, a mammalian target of rapamycin complex 1 inhibitor, and YM155, a survivin inhibitor. When sensitivity to everolimus or YM155 was assessed in 12 or 11 cancer tissue‐originated spheroids, respectively, from different endometrial cancer patients, the sensitivity varied substantially. The cancer tissue‐originated spheroids sensitive to everolimus showed remarkable suppression of proliferation. The phosphorylation status of the mammalian target of rapamycin complex 1 downstream molecules before and after everolimus treatment did not predict the effect of the drug. In contrast, the cancer tissue‐originated spheroids sensitive to YM155 showed remarkable cell death. The effect of YM155 was also confirmed in vivo. The histological type correlated with YM155 sensitivity; non‐endometrioid adenocarcinomas were sensitive and endometrioid adenocarcinomas were resistant. Non‐canonical autophagic cell death was the most likely cause of cell death in a sensitive cancer tissue‐originated spheroid. Thus, sensitivity assays using cancer tissue‐originated spheroids from endometrial cancers may be useful for screening drugs and finding biomarkers.