CTLA4 and B-cell chronic lymphocytic leukemia: As some phase I/II clinical trials using systemic administration of CTLA-4 blockade in haematologic malignancies, including CLL, showed durable clinical responses in a relatively low proportion of patients [23], we hope that the results of our in vitro blocking experiments on CLL cells may provide new insights into the safety and efficacy of this potential therapeutic approach in CLL.