Phase II Clinical Trial of Alemtuzumab to Treat B-cell Chronic Lymphocytic Leukemia

Inclusion Criteria: * An established diagnosis of B-cell chronic lymphocytic leukemia(B-CLL) * Meet criteria of relapsed or refractory CLL * Presence of one or more measurable lesions * ECOG Score 0-1 * Life expectancy \> 3 months * Female patients with childbearing potential must have a negative serum pregnancy test, male and female patients must agree to use an effective contraceptive method while on study treatment, and for a minimum 1 year following study therapy. Exclusion Criteria: * Less than 2 weeks from prior anti-cancer therapy. * Allergic to the antibody or any component of the investigational product. * Other severe, concurrent diseases, including mental disorders, serious cardiac functional capacity (Class III or IV), uncontrolled diabetes. * Use of investigational agents rather than Alemtuzumab. * Active systematic infection or major organ malfunction requiring treatment. * Serum total bilirubin greater than or equal to 1.5 times upper limits of normal; or Serum alanine aminotransferase (ALT) and/or serum aspartate aminotransferase (AST) greater than or equal to 2.5 times upper limits of normal ( no liver metastases); or ALT and/or AST greater than or equal to 5 times upper limits of normal (liver metastases). * Blood urea nitrogen(BUN) greater than or equal to 1.5 times upper limits of normal or Serum creatinine greater than or equal to 1.5 times upper limits of normal. * White blood cell(WBC) count\< 3.5×109/L or Absolute neutrophil count(ANC)\<1.5×109/L or platelet count\<75×109/L or Hemoglobin\<80g/L. * Human immunodeficiency virus (HIV) positive. * Active hepatitis or a history of prior viral hepatitis B or C, or positive hepatitis B serologies without prior immunization. * Pregnant or nursing women. * Known central nervous system(CNS) metastases with B-CLL. * Active secondary malignancy. * cytomegalovirus(CMV) positive or immunodeficiency disease or after stem cell transplantation.