BAY 1143572 demonstrated significant therapeutic efficacies in ATL cell–bearing NOG mice. (A) Flow cytometric analyses of mouse liver cell suspensions are presented. The percentage of human CD45–expressing cells among mouse liver cell suspensions is indicated above each panel. Human CD45–expressing cells were plotted to show CD4 and CD8 expression. The percentage of ATL (CD4⁺ but CD8⁻) cells among human CD45⁺ cells is indicated above each panel. The top 2 lanes consist of panels showing control mice cell samples, and the bottom 2 lanes consist of panels showing BAY 1143572–treated mice cell samples. (B) Flow cytometric analyses of mice bone marrow cell suspensions. The percentage of human CD45–expressing cells among mouse bone marrow cell suspensions is indicated above each panel. Human CD45–expressing cells are plotted to show CD4 and CD8 expression. The percentage of ATL (CD4⁺ but CD8⁻) cells among human CD45⁺ cells is indicated above each panel. The top 2 lanes consist of panels showing control mice cell samples, and the bottom 2 lanes consist of panels showing BAY 1143572–treated mice cell samples. (C) Human sIL2R concentrations in serum from each of 8 ATL-bearing NOG mice. NOG mice treated with BAY 1143572 displayed significantly lower levels of sIL2R compared with control mice as determined by enzyme-linked immunosorbent assay (P = .001).