TP53 and B-cell chronic lymphocytic leukemia: Moreover, the protective effect of VE-821 could be mimicked by using AZD6738 (1 μM) (Figure 4E), an ATR inhibitor recently entered into clinical trials, which was shown to induce synthetic lethality in TP53/ATM-defective CLL cells and sensitize them to several chemotherapeutic drugs, including fludarabine [20].