Figure 2

C index and Kaplan-Meier curves for ZAP-70 evaluation according to ISO-, T- and T/B Ratio-methods (test set). Upper panels in A, B, and C show c index curves applied to ZAP-70 expression values to estimate the optimal cut-off capable to split patients into groups with different time to treatment (TTT) probabilities. X-axes report expression values for ZAP-70, expressed as percent of positive cells (A and B), or T/B ratio values (C); y-axes report the corresponding c index values. For each method, solid line indicates the chosen cut-off value. Lower panels show Kaplan-Meier curves obtained comparing TTT of patients affected by CLL expressing or not ZAP-70, as evaluated according to ISO- (A), T- (B) or T/B Ratio- (C) methods. In all plots, solid lines indicate ZAP-70 negative CLL, while dashed line indicate ZAP-70 positive CLL, according to the three readouts. In (A) Kaplan-Meier curves obtained by dividing CLL patients according to two different cut-offs (11% and 20%) for ZAP-70 evaluation are reported.