Inclusion Criteria:

- relapsed or refractory CLL/SLL

- at least 18 years of age

- able to receive outpatient treatment and follow-up at the treating institution

- completed all CLL therapies > 4 weeks prior to first study dose

Exclusion Criteria:

- previously treated with an anti-CD19 antibody therapy

- undergone prior allogeneic stem cell transplantation within 6 months or having active
graft versus host disease

- active Richter's syndrome

- designated Class III or IV by the New York Heart Association (NYHA) criteria

- history of myocardial infarction or stroke within the last 6 months

- active viral, bacterial, or systemic fungal infection requiring treatment

- HIV or Hepatitis C positive

- Hepatitis B infection