KCI-18 kidney tumor response to sunitinib combined with radiation and soy. (A) Treatment schedule for combination therapy. Mice bearing established kidney tumors were pretreated with sunitinib at 20 mg/kg per day (SU20) and/or soy at 50 mg/kg per day for 3 days, on days 10 to 12 after KCI-18 cell injection in the kidney. Then, mice received an 8-Gy radiation to the tumor-bearing kidney. Sunitinib and/or soy were continued daily for up to 27 days. (B) Response of tumor-bearing kidneys to single and combined therapy. On day 27, tumor-bearing kidneys and contralateral normal kidneys were resected and weighed. The weights of the tumor-bearing kidneys and their median are reported for eight mice per group treated with vehicle (control) or SU20 or soy (Soy) or radiation (Rad) as single modalities and radiation combined with SU20, soy, or both (*P < .05, **P < .001 compared with control mice). The normal contralateral kidney weights (NK) are shown. Inset shows the size of kidney tumors before and after resection of control mice; mice treated with radiation and SU20; and mice treated with radiation, SU20, and soy (Su + R + S) compared with normal kidney size.