A very high percentage of blasts positive for CD40 but not for CD27 is associated with improved relapse-free survival. Whereas there is no difference in relapse-free survival between patients with high and low CD27 expression (B), patients whose ALL blasts exhibit a very high percentage of CD40 expression at diagnosis as assessed by flow cytometry display significantly better relapse-free survival than patients with low CD40 expression (A). Even in the smaller subgroup of patients with a low percentage of CD27⁺ blasts at diagnosis, high CD40 expression remains a significant prognostic marker indicative of superior RFS (C). In each case the cutoff chosen for patient allocation to the TNFR “high” and “low” groups is the median of CD27⁺ or CD40⁺ blasts at diagnosis, respectively.