In vivo effect of combination therapy on the MV4-11-R tumor xenograft model. (A) Combination of ABT-869 with IDR E804 achieved impressive regression of tumor growth compared with either vehicle control or single treatment (ABT-869 or IDR E804) alone (all P < .001). (B) Excised tumor pieces from each group were embedded in paraffin and stained with anti-survivin (S), anti-Ki67 (K), and anti–cleaved PARP (C). Photographs are representative of similar observations in 3 different mice receiving same treatment. (C) Quantitative analysis of the expressions of survivin, ki67, and cleaved PARP in IHC sections from each group shown in panel B. The survivin index, ki67 index, and cleaved PARP were calculated as the percentage of positive staining cells of total nucleated cells in a ×400 field. A total of 10 fields for each index were counted. Bars indicate SD. Statistical comparison and associated P values are indicated by the broken lines in each photograph.