FIGURE 5.

Drug susceptibility assay using an ex vivo patient‐derived xenograft (PDX)‐derived cancer tissue‐originated spheroid (CTOS) culture system. A, MDM2, p53, and p21 expressions were analyzed by western blotting. B, Representative immunohistochemical staining images of the indicated proteins in PDX1 and PDX2. C, Experimental scheme for CTOS culture established from PDX. D, E, Left panels: representative images of CTOS from PDX1 (D) and PDX2 (E) on days 1 and 7 of the indicated treatment. Bar, 100 μm. Right panels: growth of CTOS. CTOS volume was calculated by dividing the volume measured on day 7 with that on day 1. Experiments were carried out in triplicate. *P <.05, CDDP + MK‐1775 vs each of the other groups. CDDP, cisplatin