Inclusion Criteria:

- Documented history of histologically confirmed B-cell CLL

- Relapsed or refractory CLL with history of prior treatment with purine nucleoside
analogue-containing regimen

- Eligible for treatment of their CLL based on criteria adapted from the National
Cancer Institute-Working Group (NCI-WG) Response Criteria for CLL

- For patients of reproductive potential (males and females), use of a reliable means
of contraception

- For females of childbearing potential, a negative serum pregnancy test

Exclusion Criteria:

- Prior use of anti-CD20 monoclonal antibody therapy (other than rituximab)

- Prior use of any non-CD20 targeted monoclonal antibody therapy within 6 months of
enrollment

- Current or recent CLL treatment

- History of severe allergic or anaphylactic reactions to human, humanized, chimeric,
or murine monoclonal antibodies

- Evidence of acute/active autoimmune hemolytic anemia or other autoimmune
complications of CLL

- Use of hematopoietic growth factors or RBC and/or platelet transfusions

- Evidence of significant uncontrolled concomitant diseases, such as cardiovascular
disease, nervous system, pulmonary, renal, hepatic, endocrine, or gastrointestinal
disorders

- Evidence of myelodysplasia or myelodysplastic changes on bone marrow examination

- History of cancer other than CLL)

- Known active bacterial, viral, fungal, mycobacterial, or other infection or any major
episode of infection requiring hospitalization or treatment with IV antibiotics or
oral antibiotics

- A major episode of infection requiring hospitalization or treatment with IV
antimicrobials within 4 weeks of screening or oral antimicrobials within 2 weeks of
screening

- Positive hepatitis B or C serology

- Positive human immunodeficiency virus (HIV) serology

- Active cytomegalovirus (CMV) disease by antigen or polymerase chain reaction testing

- Pregnancy or lactation

- CNS leukemia

- Recent major surgery, other than diagnostic surgery