A Study to Evaluate the Efficacy of Venetoclax Monotherapy in Relapsed/Refractory Participants With Chronic Lymphocytic Leukemia (CLL)

Inclusion Criteria:

Participant has Eastern Cooperative Oncology Group (ECOG) performance score of less than or equal to 2
Participant has relapsed/refractory disease (received at least 1 prior therapy)

Participant has diagnosis of CLL that meets published 2008 Modified International Workshop for Chronic Lymphocytic Leukemia National Cancer Institute Working Group (IWCLL NCI-WG) Guidelines and:

has an indication for treatment according to the 2008 Modified IWCLL NCI-WG criteria
has clinically measurable disease (lymphocytosis greater than 5 × 10^9/L and/or palpable and measurable nodes by physical exam and/or organomegaly assessed by physical exam)

In addition, participants:

with or without 17p deletion or TP53 mutation, assessed by a local laboratory in bone marrow or peripheral blood are eligible
may have been previously treated with a prior B-cell receptor inhibitor
Participant must have adequate bone marrow function, coagulation profile, renal, and hepatic function, per laboratory at Screening

Exclusion Criteria:

Participant has developed Richter's transformation or Prolymphocytic leukemia
Participant has previously received venetoclax

History of active malignancies other than CLL within the past 2 years prior to first dose of venetoclax, with the exception of:

adequately treated in situ carcinoma of the cervix uteri
adequately treated basal cell carcinoma or localized squamous cell carcinoma of the skin
previous malignancy confined and surgically resected (or treated with other modalities) with curative intent
Participant has active and uncontrolled autoimmune cytopenias (for 2 weeks prior to Screening), including autoimmune hemolytic anemia and idiopathic thrombocytopenic purpura despite low dose corticosteroids
Participant has undergone an allogeneic stem cell transplant

Treatment with any of the following within five half-lives or 14 days (if half-life unknown) as applicable prior to the first dose of venetoclax, or clinically significant adverse effect(s)/toxicity(s) of the previous therapy have not resolved to < National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) v4.03 Grade 2:

Any anti-cancer therapy including chemotherapy, or radiotherapy;
Investigational therapy, including targeted small molecule agents
Participant is human immunodeficiency virus (HIV) positive
Participant has known allergy to both xanthine oxidase inhibitors and rasburicase