Recently, ATM-deficient mantle cell lymphoma, chronic lymphocytic leukemia, and T-prolymphocytic leukemia have been shown to be more sensitive to PARP inhibitors than ATM-proficient cells [16,17] suggesting that ATM mutation/inactivation might predict responses of individual tumors to PARP inhibitors. This evidence concerns the gene PARP1 and B-cell chronic lymphocytic leukemia.