This protocol is being run to determine the best phase II dose and schedule of obatoclax in patients with previously untreated CLL.

Both 1 hour and 3 hour infusions of obatoclax every 3 weeks will be evaluated in ascending doses.

Inclusion Criteria:

• Histologically or cytologically confirmed B-CLL
• Previous standard systemic chemotherapy, including fludarabine. There are no limitations on additional, allowable type and amount of prior therapy. Acute toxicities from prior therapy must have resolved to ≤Grade 1
• Age ≥18 years
• ECOG Performance Status ≤1
• Life expectancy of >8 weeks

Exclusion Criteria:

• Patients receiving any other investigational agents (e.g., under another IND) or commercial agents or therapies administered with the intent to treat their malignancy
• Patients with history of seizure disorders
• Pregnant women and women who are breast feeding
• HIV-positive patients receiving combination anti-retroviral therapy