All ABT-737–sensitive HMCLs harbor a t(11;14) and could be identified by their BCL2/MCL1 ratio. (A) HMCLs (n = 25) were cultured with increasing doses of ABT-737 for 48 hours then stained with Apo 2.7 for flow cytometry analysis. The means of 3 independent experiments are shown. The LD₅₀ value is determined for each cell line (ABT-737 concentrations where 50% of cells are stained with Apo 2.7). Analysis of BCL2 (B) and MCL1 expression (C) in function of ABT-737 sensitivity (LD₅₀) of HMCLs. Bcl-2 and Mcl-1 expression levels were defined by Affymetrix microarray and plotted against the LD₅₀. The Spearman rank correlation coefficient is indicated. (D) Analysis of BCL2/MCL1 expression ratio in function of ABT-737 sensitivity (LD₅₀) of HMCLs. The Spearman rank correlation coefficient is indicated. The cut-off value (0.44) determined as the mean of Bcl-2/Mcl-1 ratio of resistant cell lines +2 SD (P < .001; sensitivity = 100%; specificity = 94.7%; 85% predictive positive value; and 100% negative predictive value) is indicated. Comparisons of BCL2/MCL1 gene expression ratio (E) and ABT-737 LD₅₀ (F) in the different molecular groups of HMCLs.