Effect of bevacizumab on the leukemic cell burden in the CNS of xenograft recipients. Leukemic mice showing >90% engraftment in the BM received intraperitoneal bevacizumab or normal saline (NS). (A) Mean burden of leukemic cells in the BM of each group at the start and the end of treatment. (B) Mean burden of leukemic cells in the BM and CNS of each group at the end of treatment showing significant lower leukemic cells in the CNS of bevacizumab-treated mice. Data show mean and analyzed with 2-sided, unpaired Student t test; ***P < .001. (C) Representative immunohistochemical staining for human CD19 in tissue sections from the CNS of NS- and bevacizumab-treated mice. Thick blue arrows mark leukemic cells. Scale bar, 250 μm. (D) The percentage of TUNEL-positive leukemic cells in the CNS was counted from 3 distinct areas of the each section of 2 control mice and 3 bevacizumab-treated mice. Graph shows the percentage of TUNEL-positive cells in the CNS.