The most commonly used chemotherapy drugs approved by the Food and Drug Administration (FDA) for the treatment of CLL include the alkylating agents bendamustine 1 [8] and cyclophosphamide, together with the nucleoside fludarabine phosphate 2, while the adenosine deaminase (ADA) inhibitor pentostatin 3 is also used in CLL patients who have relapsed (Figure 1). Here, ADA is linked to B-cell chronic lymphocytic leukemia.