Inclusion Criteria:

• A diagnosis of B-CLL; according to the NCI WG Criteria.
• WHO performance status of 0, 1, or 2.
• Life expectancy ≥ 12 weeks.
• Previous therapy with at least one but no more than 5 regimens (single agent or combination regimen). One therapy regimen is defined as consecutive, contiguous cycles of the same drug(s) with no treatment interruptions lasting > 3 months.
• Patient requires treatment for CLL per the following criteria: -Rai stage III or IV; -Rai stage 0-II with at least one of the following - evidence of progressive marrow failure as manifested by the development of, or worsening of, anemia and/or thrombocytopenia; Massive (i.e. greater than 6 cm below the left costal margin) or progressive splenomegaly; Progressive lymphocytosis with an increase of greater than 50% over a 2-month period or an anticipated doubling time of less than 6 months; Lymphocyte count > 100 x 10^9/L; B symptoms.
• More than 3 weeks since prior chemotherapy. Patient must have recovered from the acute side effects incurred as a result of previous therapy.
• More than 3 weeks since using investigational agents. Patient must have recovered from the acute side effects incurred as a result of previous therapy.
• Serum creatinine and conjugated (direct) bilirubin less than or equal to 2 x the institutional upper limit of normal (ULN) unless secondary to direct infiltration of the liver with CLL.
• Female patients with childbearing potential must have a negative pregnancy test (serum or urine) within 2 weeks of first dose of study drug(s). All patients must agree to use an effective contraceptive method while on study treatment, if appropriate, and for a minimum of 6 months following study therapy.
• Signed, written informed consent (in the US, includes HIPPA authorization)

Exclusion Criteria:

• Positive Coombs test and evidence of active hemolysis.
• Platelet count less than 50 x 10^9/L without splenomegaly.
• History of anaphylaxis following exposure to rat or mouse derived CDR-grafted humanized monoclonal antibodies.
• Previously treated with CAMPATH.
• Previous bone marrow transplant.
• Known central nervous system (CNS) involvement with B-CLL
• Active infection, including human immunodeficiency virus (HIV) positive.
• Active secondary malignancy.
• Recent documented history (within 2 years) of active tuberculosis (TB), current active TB infection, currently receiving anti-tuberculosis medication (e.g., INH, rifampin, streptomycin, pyrazinamide, or others).
• 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)).
• Other severe, concurrent diseases (e.g., cardiac or pulmonary disease), mental disorders, or major organ malfunction (liver, kidney) that could interfere with the patient ability to participate in the study.
• Pregnant or nursing women.
• CMV positive by PCR (above the level of detection). A patient that is PCR positive will require treatment to reduce the viral load to a non-detectable level; but such a patient may be considered for study entry once the infection has been treated.
• Medical condition requiring chronic use of oral corticosteroids at a dose higher than physiologic replacement.