KPT-330+CS shows potent antitumor effect without substantial in vivo organ toxicity. Tumor volume curves (A) and extracted tumor (B) of NSG mice transplanted subcutaneously with JeKo-1 cells and treated with vehicle, KPT-330, CS, or KPT-330+CS. Tumor volumes were measured daily for 26 days. (C) Histopathological assessment of organs from non–tumor-bearing mice treated with KPT-330+CS or vehicle for 26 days (original magnification ×10; hematoxylin and eosin stain). Grade I renal tubular hyperplasia (black arrowhead points to a renal tubule with increased cellularity) was seen in 4 of 5 mice as compared with 1 of 5 mice in the treatment and control groups, respectively. (D) The expression of CRM1, Rad51, and TYMS proteins assessed through immunohistochemistry on tumor tissue following treating tumor-bearing NSG mice with respective drug combinations for 26 days (original magnification ×100). ***P < .0005. The paired Student t test was used to compare all continuous variables. A value of P < .05 was considered statistically significant.