The primary objective of this study is to confirm the safety profile of alemtuzumab 30 mg (the US/European Union (EU) approved dose) in Japanese patients with relapsed or refractory Chronic Lymphocytic Leukemia (CLL).

NOTE: This study was previously posted by Bayer. In December 2009, this study was acquired by Genzyme Corporation. Genzyme Japan K.K. is the sponsor of the trial.

Inclusion Criteria:

• B-cell Chronic Lymphocytic Leukemia (B-CLL) according to the 1996 National Cancer Institute-sponsored Working Group (NCI-WG) Criteria
• One or more, but <= 3 previous treatment regimens for Chronic Lymphocytic Leukemia (CLL)
• Patient requires treatment for CLL (Rai stage III and IV disease or stage 0 to II disease with evidence of progression)
• Adequate bone marrow, liver and renal function
• More than 4 weeks since prior chemotherapy or chemoimmunotherapy, including investigational agents, for the treatment of CLL. Patient must have recovered from the acute side effects incurred as a result of previous therapy
• World Health Organization (WHO) Performance Status (PS) 0,1
• Life expectancy of at least 24 weeks
• Women of childbearing potential must have a negative serum or urine pregnancy test performed within 7 days prior to the start of treatment. Both men and women enrolled in this trial must use adequate barrier birth control measures during the course of the trial and 2 weeks after the completion of trial
• Written informed consent

Exclusion Criteria:

• Known human immunodeficiency virus (HIV) seropositivity
• Active hepatitis or a history of prior viral hepatitis B or hepatitis C, or positive hepatitis B serologies. Patients with a positive hepatitis B surface antibody (HBsAb) test with a documented history of prior hepatitis B immunization are eligible as long as other criteria are met (i.e., negative tests for : hepatitis B surface antigen [HBsAg], hepatitis B core antibody [HBcAb] and hepatitis C virus antibody [HCVAb])
• Active uncontrolled infection
• Recent documented history (within 2 years) of active tuberculosis (TB), current active TB infection, currently receiving anti-tuberculous medication (e.g., isoniazid, rifampin, streptomycin, pyrazinamide, or others)
• Positive cytomegalovirus (CMV) by Polymerase Chain Reaction (PCR) assay
• Transformation to aggressive lymphoma (e.g., Richter's syndrome)
• Past history of anaphylaxis following exposure to humanized monoclonal antibodies
• Previous treatment with alemtuzumab
• Previous hematopoietic stem cell transplant
• Pregnant or breast-feeding patients
• Central nervous system (CNS) involvement with CLL
• Other severe, concurrent diseases (e.g., cardiac or pulmonary disease), mental disorders, or major organ malfunction (e.g., liver, kidney) that could interfere with the patient's ability to participate in the study
• Medical condition requiring chronic use of oral corticosteroids at a dose higher than physiologic replacement.
• Active malignancy, other than CLL, which needs therapy with anti-cancer drug(s)
• Autoimmune anemia and/or thrombocytopenia
• Small lymphocytic lymphoma