Chronic lymphocytic leukemia is the most common leukemia in the United States. It is a slowly progressive disease, with an 82% five-year survival rate. The treatment strategies are highly individualized with patients in the early and stable stages typically not requiring treatment. However, those with progressive or clinically advanced disease will require treatment. Cytotoxic drugs, such as the alkylating agents, purine nucleoside antagonists, and immunotherapeutic agents, have been the mainstay of chemotherapeutic treatment in CLL. However, given the lack of therapeutic specificity, these medications (especially older ones) have limited tolerability due to side effects. In this paper, we will discuss the data on the use of phosphatidylinositol 3 kinase inhibitor Idelalisib in the management of patients with chronic lymphocytic leukemia. The preclinical and clinical data thus far demonstrate that Idelalisib produces a dramatic and durable response in patients with chronic lymphocytic leukemia and without causing significant toxicity. Moving forward, the ongoing clinical trials will help address the various questions currently being raised regarding the long-term application and safety of Idelalisib. With greater clinical experience following more widespread use of Idelalisib, we will be able to determine the optimal combination therapies in treatment-na？ve and relapsed/refractory patients, resulting in more individualized therapeutic strategies for patients with chronic lymphocytic leukemia. 1. Introduction Chronic lymphocytic leukemia (CLL) is a lymphoid malignancy characterized by the accumulation and proliferation of nonfunctional and monoclonal small CD5/CD19/CD-20/CD23-positive lymphocytes in the blood, bone marrow, and lymphoid tissues [1, 2]. It is the most common adult leukemia in the United States, with 15,680 new cases and estimated 4,850 deaths reported by the American Cancer Society in 2013 [3]. CLL is primarily a disease of old age with the median age at diagnosis being 72 years; its incidence in the male population is reported to be twice that of the female population [4]. Diagnosis of CLL requires the presence of at least 5,000 monoclonal mature appearing B-lymphocytes per microliter in the peripheral blood [5]. CLL is a slowly progressive disease, with an 82% five-year survival rate [3]. The treatment strategies of CLL are highly individualized with patients in the early and stable stages of CLL not requiring treatment. However, those with progressive or clinically advanced disease will require treatment. Cytotoxic drugs, such as the
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