However, arsenic trioxide (As2O3) has attracted worldwide interest in the field of oncology because of its substantial anticancer activity in patients with acute promyelocytic leukemia (APL). Interestingly, a number of studies have revealed that As2O3 can induce apoptosis, not only in APL, but also in a wide variety of hematologic malignancies, including CLL, either as monotherapy or combined therapy. Investigators previous study has also suggested that As2O3 could induce CLL cells apoptosis, and could be an efficient therapeutic agent for CLL.